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  • 1995-1999  (568)
  • 1980-1984
  • 1995  (568)
  • Genetics  (327)
  • Physical Chemistry  (241)
  • Nuclear reactions
  • 1
    Electronic Resource
    Electronic Resource
    Characterization of Japanese families with early-onset type 2 (non-insulin dependent) diabetes mellitus and screening for mutations in the glucokinase and mitochondrial tRNALeu(UUR) genes (1995)
    Springer
    Acta diabetologica 32 (1995), S. 17-22 
    Details
    ISSN: 1432-5233
    Keywords: Maturity-onset diabetes of the young (MODY) ; Genetics ; Diabetes mellitus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Genetic linkage studies of families with earlyonset type 2 diabetes have facilitated the identification of diabetes-susceptibility genes. In order to assess the feasibility of using linkage approaches to identify genes responsible for the development of type 2 diabetes in Japanese subjects, we examined our clinical records for multigenerational families suitable for genetic studies. We identified 16 families in which at least one subject was diagnosed with type 2 diabetes before 25 years of age. Seven of these families had a pattern of inheritance consistent with a diagnosis of maturity-onset diabetes of the young (MODY) and nine families showed a complex pattern of inheritance of type 2 diabetes with transmission of diabetes-susceptibility genes from both parents. The glucokinase and mitochondrial tRNALeu(UUR) genes were screened for mutations in at least one affected subject from each family in order to assess the contribution of mutations in these genes to the development of the diabetes. No mutations were found, which suggests that the diabetes in these families resulted from mutations in other genes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00581039
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  • 2
    Electronic Resource
    Electronic Resource
    Identification of genomic regions affecting plant height in sorghum and maize (1995)
    Springer
    Theoretical and applied genetics 90 (1995), S. 380-388 
    Details
    ISSN: 1432-2242
    Keywords: Genetics ; Breeding ; Sorghum bicolor Zea mays
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The objective of this study was to use restriction fragment length polymorphisms (RFLPs) to determine the genetic location and effects of genomic regions controlling plant height in sorghum. F2 plants (152) from the cross CK60 x PI229828 were used. Genomic and cDNA clones (106) identified 111 loci distributed among ten linkage groups covering 1299 cM. Interval mapping identified four regions, each in a separate linkage group. These regions may correspond to loci (dw) previously identified by alleles with qualitative effects. Also, these regions identified in sorghum may be orthologous to those previously reported for plant height in maize. Gene effects and gene action varied among genomic regions. In each region, PI229828 alleles resulted in increased plant height. Each region accounted for 9.2–28.7% of the phenotypic variation. Positive, additive effects ranged from 15 to 32cm. Tallness was dominant or overdominant and conferred by alleles from PI229828 for three quantitative trait loci (QTL). At the fourth QTL, PI229828 contributed to increased plant height, but short stature was partially dominant. One digenic interaction was significant. The presence of a PI229828 allele at one region diminished the effects of the other region. A multiple model indicated that these four regions collectively accounted for 63.4% of the total phenotypic variation. The utility of this information for germplasm conversion through backcross breeding is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00221980
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  • 3
    Electronic Resource
    Electronic Resource
    Mixed desmoplastic primitive neuroepithelial tumor of infancy: a light microscopic, immunocytochemical, ultrastructural and genetic study (1995)
    Springer
    Acta neuropathologica 89 (1995), S. 99-104 
    Details
    ISSN: 1432-0533
    Keywords: Primitive neuroepithelial tumor ; Desmoplastic small cell tumor ; Brain tumor of infancy Immunocytochemistry ; Genetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract We describe a case of a desmoplastic brain tumor which was initially resected from the right fronto-temporal region in a 2 year-old boy. This nodular, calcified tumor was vascularized by the internal carotid artery and the middle meningeal artery branches. Grossly, it contained several mucoid cysts. Light microscopy showed cords or nests of small cuboidal cells surrounded by a loose connective tissue and desmoplasic areas containing fibers and spindle cells. The cuboidal cells expressed epithelial, neuronal and neuroendocrine markers. Some foci of spindle cells showed glial differentiation. The tumor recurred 16 months later and displayed some characteristics of the small cell neuroepithelial component, mitoses being conspicuous. Electron microscopy revealed undifferentiated clear cells, some containing neurosecretory granules. Karyotyping demonstrated the following formula: 〈 15 〉 46, t(8;11) (a13; q11). The chromosome 11 breakpoint was different from that described in Ewing's sarcoma. This isolated translocation has not been previously reported to our knowledge. These unusual features lead us to report this case and to discuss its pathogenesis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00294266
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  • 4
    Electronic Resource
    Electronic Resource
    Fetal brain disruption sequence in sisters (1995)
    Springer
    European journal of pediatrics 154 (1995), S. 654-657 
    Details
    ISSN: 1432-1076
    Keywords: Key words Fetal development ; Brain diseases ; Genetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract We report two female siblings with the fetal brain disruption sequence. Extensive investigation of both children failed to define a definitive aetiology but clinical and laboratory findings are consistent with a hitherto unknown storage disease. We postulate that the accumulation of a neurotoxic metabolite may be responsible for the disease phenotype observed. This is the first report of recurrence of the fetal brain disruption sequence and supports the existence of a genetic form of this condition. Previous reports have emphasized possible environmental aetiologies. Infants with fetal brain disruption sequence should be investigated exhaustively and, in the absence of definitive evidence of an environmental cause, the possibility of a genetic aetiology should be considered. In some families the recurrence risk may be as high as one in four.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004310050366
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  • 5
    Electronic Resource
    Electronic Resource
    Floating-Harbor syndrome: description of a further patient, review of the literature, and suggestion of autosomal dominant inheritance (1995)
    Springer
    European journal of pediatrics 154 (1995), S. 658-661 
    Details
    ISSN: 1432-1076
    Keywords: Key words Floating-Harbor ; syndrome ; Growth retardation ; Dysmorphology ; Genetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The Floating-Harbor syndrome is a growth retardation syndrome with delayed bone age, speech development, and typical facial features. The face is triangular with deep-set eyes, long eyelashes, bulbous nose, wide columella, short philtrum, and thin lips. We present an additional patient and review 16 cases from the literature. The possible phenotype in the patient's mother suggests a dominant mode of inheritance for the syndrome. Conclusion The Floating Harbor syndrome is a growth deficiency syndrome characterized by proportionate short stature, characteristic face and delayed speech development. Inheritance is possibly autosomal dominant.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004310050367
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  • 6
    Electronic Resource
    Electronic Resource
    Genetic counselling on brittle grounds: recurring osteogenesis imperfecta due to parental mosaicism for a dominant mutation (1995)
    Springer
    European journal of pediatrics 154 (1995), S. 123-129 
    Details
    ISSN: 1432-1076
    Keywords: Key words Osteogenesis imperfecta ; Collagen I ; Mosaicism ; Genetics ; Recurrence risk
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Osteogenesis imperfecta (OI), a dominantly inherited connective tissue disorder, is usually caused by defects in collagen I. There is growing evidence for parental mosaicism that results in affected children born to unaffected parents. This situation poses a difficult task for the geneticist because a mosaic parent may appear clinically healthy while carrying the mutation in a fraction of her or his gonadal cells. To illustrate this problem, we report a Swiss couple whose first child was affected with severe OI. The unexpected recurrence of the disorder in the second child raised the suspicion of a recessive trait or, rather, of parental mosaicism. We identified the responsible collagen mutation in the COL1A2 gene (Gly688Ser in the α2(I)-chain) in both children and demonstrated the father to be a somatic mosaic for this mutation and to have subtle clinical signs such as soft skin and short stature that may be a result of his mosaic state.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004310050261
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  • 7
    Electronic Resource
    Electronic Resource
    Fetal brain disruption sequence in sisters (1995)
    Springer
    European journal of pediatrics 154 (1995), S. 654-657 
    Details
    ISSN: 1432-1076
    Keywords: Fetal development ; Brain diseases ; Genetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract We report two female siblings with the fetal brain disruption sequence. Extensive investigation of both children failed to define a definitive aetiology but clinical and laboratory findings are consistent with a hitherto unknown storage disease. We postulate that the accumulation of a neurotoxic metabolite may be responsible for the disease phenotype observed. This is the first report of recurrence of the fetal brain disruption sequence and supports the existence of a genetic form of this condition. Previous reports have emphasized possible environmental aetiologies. Infants with fetal brain disruption sequence should be investigated exhaustively and, in the absence of definitive evidence of an environmental cause, the possibility of a genetic aetiology should be considered. In some families the recurrence risk may be as high as one in four.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02079071
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  • 8
    Electronic Resource
    Electronic Resource
    Floating-Harbor syndrome: description of a further patient, review of the literature, and suggestion of autosomal dominant inheritance (1995)
    Springer
    European journal of pediatrics 154 (1995), S. 658-661 
    Details
    ISSN: 1432-1076
    Keywords: Floating-Harbor syndrome ; Growth retardation ; Dysmorphology ; Genetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Abstract The Floating-Harbor syndrome is a growth retardation syndrome with delayed bone age, speech development, and typical facial features. The face is triangular with deep-set eyes, long eyelashes, bulbous nose, wide columella, short philtrum, and thin lips. We present an additional patient and review 16 cases from the literature. The possible phenotype in the patient's mother suggests a dominant mode of inheritance for the syndrome. Conclusion The Floating Harbor syndrome is a growth deficiency syndrome characterized by proportionate short stature, characteristic face and delayed speech development. Inheritance is possibly autosomal dominant.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02079072
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  • 9
    Electronic Resource
    Electronic Resource
    Genetische Faktoren bei der Entstehung und Progression maligner Melanome (1995)
    Springer
    Der Hautarzt 46 (1995), S. 394-399 
    Details
    ISSN: 1432-1173
    Keywords: Schlüsselwörter Malignes Melanom ; Genetische Instabilität ; Genetik ; Syndrom der dysplastischen Nävi ; Xeroderma pigmentosum ; Key words Malignant melanoma ; Genetic instability ; Genetics ; Dysplastic nevus syndrome ; Xeroderma pigmentosum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Summary Exposure of the skin to ultraviolet irradiation is an important risk factor for the development of malignant melanoma, with UVA possibly playing an important role. Hereditary factors are also relevant. In the dysplastic nevus syndrome a genetic instability has been shown by different methods. In xeroderma pigmentosum the DNA repair defect is thought to be responsible for the high incidence of malignant melanoma. Frequent and non-random changes in certain chromosomes have been demonstrated in melanoma cells. These might contain sequences that control melanoma growth or melanoma suppressor genes. Especially the short arm of chromosome 9 is thought to contain one of these genes. This hypothesis is supported by a genetic linkage analysis in melanoma families and the demonstration of a germ line deletion of the locus 9p21 in a patient with eight primary melanomas. Changes in known tumor suppressor genes and oncogenes have also been reported in melanoma, but no consistent sequence of genetic events is known.
    Notes: Zusammenfassung Die Exposition der Haut mit ultravioletten Strahlen ist ein wichtiger Risikofaktor für die Entwicklung eines malignen Melanoms. Möglicherweise spielt hierbei UVA-A eine besondere Rolle. Daneben sind hereditäre Faktoren von Bedeutung. Während beim Syndrom der dysplastischen Nävi eine genetische Instabilität mit verschiedenen Methoden nachgewiesen wurde, wird bei Xeroderma pigmentosum der DNA-Reparaturdefekt für die hohe Melanominzidenz verantwortlich gemacht. In Melanomzellen sind überzufällig häufig karyotypische Veränderungen in bestimmten Chromosomen gefunden worden. Diese enthalten möglicherweise Melanomwachstumsregulierende Sequenzen oder Melanom-Suppressorgene. Insbesondere der kurze Arm des Chromosoms 9 steht in Verdacht, eines dieser Gene zu enthalten. Diese Hypothese wird auch unterstützt durch eine genetische Kopplungsanalyse an Melanomfamilien und dem Nachweis einer Keimbahndeletion des Lokus 9p21 bei einer Patientin mit 8 primären Melanomen. Veränderungen an bereits bekannten Tumorsuppressorgenen oder Onkogenen sind ebenfalls in Melanomen beschrieben worden, ohne daß jedoch eine konsistente Reihenfolge von genetischen Ereignissen bekannt wäre.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s001050050272
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  • 10
    Electronic Resource
    Electronic Resource
    Allelic relationships between genes for resistance to tomato spotted wilt tospovirus in Capsicum chinense (1995)
    Springer
    Theoretical and applied genetics 90 (1995), S. 146-149 
    Details
    ISSN: 1432-2242
    Keywords: Capsicum chinense ; Resistance gene ; Genetics ; Pepper ; Tomato spotted wilt virus ; Tospoviruses
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Pepper (Capsicum chinense Jacq.) has been reported to be an important reservoir of resistance genes to tomato spotted wilt virus (TSWV). The genes for TSWV resistance present in three C. chinense lines (‘PI 152225’, ‘PI 159236’ and ‘Panca’) were investigated for allelism. All resistant lines were crossed with each other. Parents, F1, backcrosses and F2 populations (including reciprocals) developed from those crosses were mechanically inoculated with a highly virulent TSWV isolate. Susceptible C. annuum cv ‘Magda’ was used to check inoculum virulence. Fifty plants of the F1 hybrids; ‘Magda’ x ‘PI 152225’, ‘Magda’ x ‘PI 159236’, and ‘Magda’ x 'Panca, were also inoculated with the TSWV isolate. The resistance response in all C. chinense sources was associated with a localized, hypersensitive-like reaction that was phenotypically expressed as a prompt formation of large local lesions accompanied by premature leaf abscission. All F1 generations presented a final score of resistant; indicating that the expression of resistance to TSWV is conditioned by a dominant gene regardless of the source. The absence of segregation for resistance to TSWV that was observed in all generations of the crosses between C. chinense lines indicated that either a tightly linked group of genes exists or that the resistance is governed by the same single major gene (probably the already described Tsw gene). Previous reports have indicated that the Tsw gene is not effective against tospovirus members of serogroup II, i.e. tomato chlorotic spot virus (TCSV) and groundnut ring spot virus (GRSV). In the assay described here, all of the C. chinense lines showed, after mechanical inoculation, an identical susceptibility response to the TCSV and GRSV isolates.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00221009
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  • 11
    Electronic Resource
    Electronic Resource
    Diallel analysis for mineral element absorption in tropical adapted soybeans [Glycine max (L.) Merrill] (1995)
    Springer
    Theoretical and applied genetics 90 (1995), S. 707-713 
    Details
    ISSN: 1432-2242
    Keywords: Mineral stress ; Nutrient efficiency ; Aluminium tolerance ; Inheritance ; Genetics ; Breeding
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The Brazilian tropical adapted soybeans contains, in addition to superior morphological characters, genetic factors for tolerance to cultivation in acidic, mineral-stressed soils. However, the selection process for these hindrances has been empirical, and information on the genetics of mineral element uptake by the plant is necessary. The objective of this investigation was to identify the mode of inheritance for the absorption of phosphorus, potassium, calcium, magnesium, iron, aluminium, manganese, zinc and copper in a 9 × 9 diallel cross. General combining ability (GCA) was higher than specific combining ability (SCA), with the exception of copper, manganese and zinc, indicating predominantly additive effects. The ratios of GCA/SCA varied between 3.4 (calcium) and 8.5 (magnesium). The regression of covariance (Wr) on variance (Vr) showed that the additive-dominance model explained the genetic differences in this germ plasm. However, the detection of overdominance could be related to possible heterozygosity in the parental varieties for mineral absorption. Broad-sense heritability values were higher than narrow sense heritability values for aluminium, iron, potassium, calcium and magnesium, being in the range of 67.9–86.9% and 42.0–56.6%, respectively. This is an indication that soybeans can be further improved to efficient utilisation of nutrients and to tolerate toxic factors in the soil.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00222137
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  • 12
    Electronic Resource
    Electronic Resource
    Opioid operant self-administration, analgesia, stimulation and respiratory depression inμ-deficient mice (1995)
    Springer
    Psychopharmacology 117 (1995), S. 23-31 
    Details
    ISSN: 1432-2072
    Keywords: Opioid ; Genetics ; Self-administration ; CXBK/ByJ ; Reinforcement
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract It is commonly thought thatμ-receptors play an important role in the reinforcing effects of opioids. In the present study, inbred strains widely divergent in CNS opiate receptor densities were used to investigate the influence of genetic variation in receptor concentration on opioid-reinforced behavior. In particular, the CXBK/ByJ mice were used as an investigative tool because of their significantly lower number of CNSμ opioid receptors. The behavioral pharmacology of opioids in theμ-deficient CXBK/ByJ mice was compared to other commonly used inbred mouse strains, C57BL/6J and BALB/cJ, and the opiate receptor rich CXBH/ByJ mice. Operant opioid reinforced behavior, opioid-induced locomotor stimulation, analgesia and respiratory depression were investigated in all four inbred strains. To assess the acquisition and maintenance of opioid reinforced behavior, oral self-administration of the potent benzimidazole opioid, etonitazene, was determined using an operant fixed-ratio schedule of reinforcement (FR 8). Acquisition of etonitazene-reinforced behavior was established in all four strains including theμ-deficient CXBK/ByJ mice. However, there were significant genetic differences in the amount of drug intake during the maintenance of opioid-reinforced behavior and extinction behavior following vehicle substitution. For example, drug intake was significantly greater in the BK versus BH mice during the maintenance phase and an extinction burst was seen in the BH but not the BK mice following vehicle substitution. Thus,μ-receptor density may not account for individual variability in the acquisition of opioid-reinforced behavior under these conditions. Sensitivity to etonitazene-induced respiratory depression, stimulation of locomotor activity and analgesia were unrelated to drug intake during self-administration sessions across these four inbred strains. These data indicate that inherited differences in CNSμ-opiate receptor concentrations do not affect acquisition of etonitazene-reinforced behavior.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02245094
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  • 13
    Electronic Resource
    Electronic Resource
    Chromosomal mapping of loci influencing sensitivity to cocaine-induced seizures in BXD recombinant inbred strains of mice (1995)
    Springer
    Psychopharmacology 117 (1995), S. 62-66 
    Details
    ISSN: 1432-2072
    Keywords: Cocaine ; Quantitative trait loci ; Seizure ; Recombinant inbred strains ; Genetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Among inbred mice, genetic factors mediate differences in sensitivity to the convulsant properties of cocaine; however, the gene(s) underlying cocaine's effects have not been identified. To help elucidate the gene(s) responsible for cocaine seizure susceptibility, we used recombinant inbred-quantitative trait loci (RI-QTL) analyses to identify chromosomal loci associated with cocaine-induced seizures. RI-QTL analyses seek to identify associations between a quantitative measure of a particular phenotype and one or more previously mapped marker genes across a panel of RI strains. This report describes an RI-QTL analysis of cocaine seizure susceptibility among 26 BXD RI strains. These strains showed a skewed, bimodal range of seizure susceptibility which could be the result of one or more modifying genes acting in concert with a major gene to influence cocaine sensitivity. Correlating the percent seizures displayed by each strain following 60 mg/kg cocaine with chromosomal marker data for these strains revealed a number of significant correlations clustered in two regions on chromosomes 12 and 6. This is the first identification of putative chromosomal loci associated with a cocaine-related phenotype and should facilitate identification of the gene(s) underlying cocaine toxicity and other cocaine-related phenotypes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02245099
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  • 14
    Electronic Resource
    Electronic Resource
    Sex segregation ratio and gender expression in the genus Actinidia (1995)
    Springer
    Sexual plant reproduction 8 (1995), S. 129-132 
    Details
    ISSN: 1432-2145
    Keywords: Sex control ; Disomic segregation ; Dioecy Kiwifruit ; Genetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The sex segregation ratio was checked in bi-parental families of Actinidia deliciosa (2n=6x=174) obtained by crossing four females (A12, Mo3, Br4, Hw1) with two males (T2, M1) and one fruiting male (M3h, subandroecious) according to a factorial mating design. The M3h fruiting male was also selfed. The sex ratio was checked in maternal families of A. kolomikta (2n=2x) and A. chinensis (2n=2x) as well as in A. deliciosa. Seedlings of both diploid species took 3–4 years to progress beyond juvenility, whereas a noticeable number of seedlings from biparental crosses of A. deliciosa involving A12 and Hw1 as seed parents were still non-flowering after seven growing seasons. Open-pollinated families of both diploid and hexaploid species as well as most families from biparental crosses showed a sex segregation ratio approaching 1∶1. Subandroecious lines with different degrees of ovary and pistil development appeared in proportions of 0–4.2%, depending on the cross, but only 6 of the 2567 male vines checked were capable of setting fruit. No case of self-fertility or apomixis was detected among 1866 bagged female vines. Selfed M3h progenies gave only female and male phenotypes in a ratio of 1 female to 3 males. No off-type vines were found among these progenies. The same disomic sex segregation ratio seems to be operating at different ploidy levels in the genus Actinidia. Since selfed fruiting males produced both female and male individuals, the male sex appears to be the heterogametic one. Such evidence indicates that a monofactorial system based on one or more linked genes or on an X/Y chromosome set must be controlling sex expression. How a monofactorial sex-determining mechanism could operate in polyploids to give a 1∶1 female: male ratio is discussed. Minor modifying gene(s) seem to be responsible for the feminization of males, and their expression appears enhanced by environmental conditions. Masculinizing gene(s) seem to be lacking in female genotypes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00242255
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  • 15
    Electronic Resource
    Electronic Resource
    Genetic mapping of adrenergic receptor genes in humans (1995)
    Springer
    Journal of molecular medicine 73 (1995), S. 299-306 
    Details
    ISSN: 1432-1440
    Keywords: Adrenergic receptors ; Human genetics ; Restriction fragment length polymorphism ; Chromosome mapping ; Linkage ; Genetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract We have genetically mapped the genes encoding four human adrenergic receptors (ARs) of subtypes α1C, α2A, α2B, and β1, which are prototypic G protein coupled receptors that mediate the physiological effects of neurotransmitters, hormones, and drugs. We placed these genes onto the Cooperative Human Linkage Center (CHLC) and Genethon framework maps, within confidence intervals with greater than 1000∶1 odds. With multipoint analysis the α1C gene (locus ADRA1C) mapped to the interval between NEFL and D8S283; α2-C4, the gene encoding the α2C AR (locus ADRA2C), mapped to the interval between D4S126 and D4S62; and the α2-C10 (α2A AR)/β1 haplotype (loci ADRA2A/ ADRB1) mapped to the interval between D10S259 and D10S187. A fifth AR gene, β2, yielded significant LOD scores with markers on the long arm of chromosome 5; however, this locus (ADRB2) could not be mapped to any specific interval with odds of greater than 1000∶1. The two AR genes that are completely linked, α2-C10 and β1, were oriented on their shared 225-kb genomic fragment relative to the direction of transcription, with β1 being 5′ to α2-C10. The positioning of these genes on high-density framework maps allows them to be tested as candidates in a spectrum of diseases that might involve AR dysfunction.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00231616
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  • 16
    Electronic Resource
    Electronic Resource
    Insertion/deletion polymorphism in the angiotensin-converting enzyme gene associated with macroangiopathy and blood pressure in patients with non-insulin-dependent diabetes mellitus (1995)
    Springer
    Journal of molecular medicine 73 (1995), S. 307-311 
    Details
    ISSN: 1432-1440
    Keywords: Atherosclerosis ; Hypertension ; Type 2 diabetes ; Genetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract In the search for new risk factors for diabetic macroangiopathy the insertion/deletion (I/D) polymorphism in the angiotensin-converting enzyme gene was studied in 237 consecutive patients (125 men and 112 women) with non-insulin-dependent diabetes. The female population showed an excess of ischemic electro-cardiographic changes or definite myocardial infarctions in the patients homozygous for the deletion [D/D; odds ratio (OR) 2.8; 95% confidence interval (CI) 1.4–5.3] and in the insertion/deletion heterozygotes (I/D; OR 1.8; CI 1.1–3.1) compared with the patients homozygous for the insertion (I/I). In the total series coronary heart disease, cerebrovascular disease, and claudication were more often observed in the patients with I/D (OR 1.5; CI 1.0–2.2) or the D/D genotype patients (OR 1.7; CI 1.1–2.6) than in those with the genotype I/I. The systolic blood pressure was lower in patients with genotype I/I (138±19 mmHg) than in those with the genotype I/D (149±22 mmHg) or D/D (150±21 mmHg; P〈0.02). The prevalence of hypertension and the median urinary albumin excretion rate also tended to be lowest in the I/I genotype patients. Multiple logistic analysis revealed that in women the angiotensin-converting enzyme D/D genotype is independently associated with coronary heart disease. Our findings suggest that variation at the angiotensin-converting enzyme gene locus is one of the factors involved in the predisposition of diabetic patients to the development of arterial disease and hypertension.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00231617
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  • 17
    Electronic Resource
    Electronic Resource
    A genetic study of idiopathic focal dystonias (1995)
    Springer
    Journal of neurology 242 (1995), S. 508-511 
    Details
    ISSN: 1432-1459
    Keywords: Dystonia ; Torticollis ; Blepharospasm ; Genetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The inheritance of focal dystonias was investigated in 43 families containing 43 index cases with torticollis (n = 21), blepharospasm (n = 18) and writer's cramp (n = 4). They generated a potential population of 235 first-degree relatives, and 168 out of 179 living first-degree relatives were examined. Ten relatives with dystonia were identified in ten families. Another two parents from two of the same group of ten families were affected according to the family history. The majority of the secondary cases (six patients, five siblings, and one child) were not aware of any dystonia. The tendency for affected relatives to have the same type of dystonia as index patients was observed only for torticollis. Overall, 23% of index patients had relatives with dystonia. Segregation analysis suggested the presence of an autosomal dominant gene or genes with reduced penetrante underlying focal dystonia.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00867421
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  • 18
    Electronic Resource
    Electronic Resource
    Characterization of B-cell lines from SLE patients and their relatives (1995)
    Springer
    Rheumatology international 15 (1995), S. 89-93 
    Details
    ISSN: 1437-160X
    Keywords: SLE Lupus ; BBV transformation ; Genetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Epstein-Barr-virus (EBV)-transformed lymphoblastoid B-cell lines were generated from peripheral blood lymphocytes of 55 patients with systemic lupus erythematosus (SLE) and 44 healthy relatives. All donors have previously been extensively characterized with regard to clinical, serologic, and genetic parameters. Here, peripheral blood lymphocytes and lines were characterized for cell surface antigens. Furthermore, autoantibody production and proliferation rate of the cell lines were monitored. A significant difference between patients and relatives was the lower proliferation rate of EBV-transformed cell lines of the SLE patients. All SLE cell lines are available for interested researches and can be obtained from the European Cell Bank, Salisbury, UK.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00302123
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  • 19
    Electronic Resource
    Electronic Resource
    Industrial mycology and the new genetics (1995)
    Springer
    Journal of industrial microbiology and biotechnology 14 (1995), S. 355-364 
    Details
    ISSN: 1476-5535
    Keywords: Transformation ; Fungi ; Yeast ; Genetics ; Biotechnology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary The genetic investigation of fungi has been extended substantially by DNA-mediated transformation, providing a supplement to more conventional genetic approaches based upon sexual and parasexual processes. Initial transformation studies with the yeastSaccharomyces cerevisiae provided the model for transformation systems in other fungi with regard to methodology, vector construction and selection strategies. There are, however, certain differences betweenS. cerevisiae and filamentous fungi with regard to type of genomic insertion and the availability of shuttle vectors. Single-site linked insertions are common in yeast due to the high level of homology required for recombination between vectored and genomic sequences, whereas mycelial fungi often show a high frequency of heterologous and unlinked insertions, often in the form of random and multiple-site integrations. While extrachromosomally-maintained or replicative vectors are readily available for use with yeasts, such vectors have been difficult to construct for use with filamentous fungi. The development of vectors for replicative transformation with these fungi awaits further study. It is proposed that replicative vectors may be inherently less efficient for use with mycelial fungi relative to yeasts, since the mycelium, as an extended and semicontinuous network of cells, may delimit an adequate diffusion of the vector carrying the selectable gene, thus leading to a high frequency of abortive or unstable transformants.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01569951
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  • 20
    Electronic Resource
    Electronic Resource
    Genetic research, adolescents, and informed consent (1995)
    Springer
    Theoretical medicine and bioethics 16 (1995), S. 347-373 
    Details
    ISSN: 1573-1200
    Keywords: Genetics ; human research ; adolescence ; child ; informed consent ; decision making ; medical ethics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Philosophy
    Notes: Abstract The participation of adolescents in genetic research engenders unusual problems concerning the nature of their informed consent. In this study we analyze 70 consent documents collected from genetics investigators in the United States who conduct research with children and adolescents. We find that many consent documents do not reflect either the current or the developing ethical and legal standards for research with adolescents and that in many cases the documents are simply confusing or unclear. We make recommendations for change to reflect more adequately the changing perspective concerning the autonomous decision-making capacity of adolescents.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00995481
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  • 21
    Electronic Resource
    Electronic Resource
    Have fishes had their chips? The dilemma of threatened fishes (1995)
    Springer
    Environmental biology of fishes 43 (1995), S. 1-27 
    Details
    ISSN: 1573-5133
    Keywords: Conservation ; Extinction ; Rarity ; Biodiversity ; Breeding guilds ; Endemism ; Speciation ; Habitat degradation ; Environmental management ; Invasive fishes ; Genetics ; Ecology ; Stenotopy ; Captive propagation ; Legislation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Synopsis The conservation status and factors threatening fishes worldwide are reviewed in order to introduce a series of one-page articles on ‘Threatened fishes of the world’, and to encourage the incorporation of information on threatened fishes into international conservation programmes. Information on fish extinction and threat rates are compared with those of other animal groups, and the unique characteristics of fish conservation problems are highlighted. At present 979 species of fishes are listed as threatened in the IUCN Red List and at least 36 species and three subspecies are listed as recently extinct. It is argued that these figures are probably gross underestimates and that they may mislead conservation authorities and resource users about the seriousness of the situation. Freshwater fishes may be the most threatened group of vertebrates after the Amphibia. Urgent action is required to save many narrowly endemic, stenotopic species from extinction, especially in Africa, Asia and South America. The conservation of common species that drive essential ecological processes is also important. Anthropogenic pressures, especially habitat degradation, the introduction of invasive species and pollution, on inland and coastal waters are particularly severe and many major fish communities are threatened with elimination throughout the world. The conservation of marine fishes is complicated by the fact that it is difficult to ascertain their rarity. The importance of the retention of genetic variation is highlighted, and both orthodox and innovative conservation measures are encouraged. Further research on minimum viable populations, genetics, and the factors that cause fishes to become vulnerable to extinction, is urgently required.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00001812
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  • 22
    Electronic Resource
    Electronic Resource
    Domestication via hybridization of the wild tetraploid oats Avena magna and A. murphyi (1995)
    Springer
    Theoretical and applied genetics 91 (1995), S. 639-646 
    Details
    ISSN: 1432-2242
    Keywords: Gene introgression ; Genetics ; Linkage ; Taxonomy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The wild tetraploid (2n=28) oat species Avena magna and A. murphyi have been domesticated by having been transferred from the common oat, A sativa (2n=42), the characteristics of non-shedding spikelets glabrous and yellow lemma, and reduced awn formation. Domestication has been achieved by crossing the common oat with either of the tetraploid species and then backcrossing the pentaploid hybrids with pollen of the tetraploid wild parent. Among the BC plants obtained only a few produced some seeds. Fertile tetraploids exhibiting the domesticated syndrome have been selected for in the F2 generation. Although morphologically they were almost indistinguishable from the common oat, they were tetraploids. Wild x domesticated A. magna hybrids were vigorous and fertile. They retained their spikelets at maturity, lemma color and pubescence were intermediate between the parental lines, and awns were formed only on the lower floret of the spikelet. Each of these characteristics segregated in a 3∶1 fashion, indicating single gene control, as in the common oat. These four characteristics formed a linkage group in one F2 family and two linkage groups in the other two families. The usefulness of the domesticated tetraploids for oat research and production has been discussed. Taxonomically, the domesticated tetraploids were ranked as subspecies: A. magna ssp. domestica, and A. murphyi ssp. rigida.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00223291
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  • 23
    Electronic Resource
    Electronic Resource
    Masthead (1995)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 8 (1995) 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610080101
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  • 24
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    Electronic Resource
    Announcement (1995)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 8 (1995), S. i 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610080102
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  • 25
    Electronic Resource
    Electronic Resource
    Relative thermodynamic stabilities of 2-(methoxymethylene)tetrahydrofuran and 5-methoxymethyl-2,3-dihydrofuran (1995)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 8 (1995), S. 1-4 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The relative thermodynamic stabilities of the title compounds were determined by iodine catalyzed chemical equilibration in cyclohexane solution. The main point of interest was a determination of the thermodynamic stability of the —O—C=C—O— moiety found in the exocyclic isomers, i.e. the stabilizing effect of a MeO group on the olefinic linkage of 2-methylenetetrahydrofuran. All three isomeric compounds have essentially similar enthalpy values, which, in comparison with some previous thermodynamic data, shows that the double bond stabilization energy of the MeO group in the exo isomers is only ca 3 kJ mol-1. The entropy difference between the geometrical isomers is negligible, whereas the endo isomer is favoured by an entropy contribution of ca 9 J K-1 mol-1.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610080103
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  • 26
    Electronic Resource
    Electronic Resource
    Hyperbolic Model for the meta-para interrelationship in benzene derivatives (1995)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 8 (1995), S. 5-14 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A new approach to the long-standing problem of interrelating meta and para substituent constants is presented. An analysis of the unified σ0-scale shows that the interrelation between σ40 and σ40/σ30 can be modelled by a pair of conjugate rectangular hyperbolae, one for normal (n) and the other for special (s) substituents. The latter are characterized by a lone electron pair in the first atom. The equations σ4n0 (σ4n0 - γ0)/(σ4n0 - 2γ0) = λ0 σ3n0 and σ4s0 = γ0 + λ0 σ3s0 are derived and discussed in terms of Taft's separation of mesomeric and non-mesomeric effects. Asymptotic values λ = 0.960 γ = -0.225 were obtained by non-linear least rectangles fitting. A nonnegligible mesomeric contribution to σ0 constants for normal substituents is predicted by the hyperbolic model. The present results are at variance with Exner's analysis of the meta-para interrelationship in benzene compounds with normal substituents. This divergence is ascribed to opposite views concerning the role of the π-inductive effect.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610080104
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  • 27
    Electronic Resource
    Electronic Resource
    Photoisomerization of 3-benzoylacrylates on a silica gel surface: Effect of reaction environment on selectivity (1995)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 8 (1995), S. 31-34 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: On irradiation on a dry silica gel surface, 2-(N, N-dialkylamino)ethyl 3-benzoylacrylates undergo selective E-Z isomerization. Competing processes, such as remote-hydrogen abstraction via a charge-transfer state, with the photoisomerization in solution are completely suppressed on the surface. The yield of the Z - from the E- isomer increases with increase in the coverage of the E-isomer on the surface, reaching a limiting value. Thermal isomerization of the Z- to the E- isomer occurs easily on the silica gels surface when the alkyl group on the nitrogen atom is small. Benzoylacrylates without any amino group also undergo selective photoisomerization.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610080107
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  • 28
    Electronic Resource
    Electronic Resource
    Solvation effects on the relative basicity of propylamines (1995)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 8 (1995), S. 26-30 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Slight structural moiecular variations are known to affect different properties of compounds. In solution, different solute-solvent interactions are known also to alter the properties of numerous compounds. Quantitative structure-activity relationships (QSAR) are used regularly to analyze and predict the variations of different properties of compounds that are caused by structural variations and significant solute-solvent interactions. The relative basicities of n-propylamine, dipro;ylamine and tripropylamine were determined in nine different solvents from potentiometric titrations. QSAR that were developed from these experimental basicity values were used to evaluate the type and significance of the solute-solvent interactions. The important interactions that influence basicity variations for the propylamines studied are dipolarity-polarizability interaction between the solute and the solvent and hydrogen bonds from the propylammonium ions to basic solvents. The role of hydrogen bonds from the propylamines to acidic solvents is minor.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610080106
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  • 29
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    Electronic Resource
    Interrelations Of the energetics of amides and alkenes: Enthalpies of formation of N,N-dimethyl derivatives of pivalamide, 1-adamantylcarboxamide and benzamide, and of styrene and its α-, trans-β- and β,β-methylated derivatives (1995)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 8 (1995), S. 15-25 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The enthalpies of formation of the condensed phase and gaseous N,N-dimethyl derivatives of pivalamide, 1-adamantylcarboxamide and benzamide were determined by combustion calorimetry and the associated enthalpies of vaporization and sublimation. The enthalpies of formation of styrene and its α-, trans-β- and β,β-methylated derivatives were determined from measurements of their enthalpies of hydrogenation in dilute hydrocarbon solution. Strain and resonance effects of amides and alkenes are discussed in terms of the exo-/endothermicity of the following reactions: and in terms of the difference of enthalpies of formation of the isomeric (Z)- and E-RCH=CHCH3.
    Additional Material: 6 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610080105
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  • 30
    Electronic Resource
    Electronic Resource
    Substituent effects for the BF3-mediated reactions of allyltributyltin and allyltriethyllead with benzaldehyde (1995)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 8 (1995), S. 35-40 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Substituent effects were measured for the reactions of substituted benzaldehydes with allytributylin (1) and allyltriethyllead (2) reagents in the presence of BF3.OEt2 in CH2Cl2. The Hammett p values were small and positive at 25 °C and negative at -78 °C for both 1 and 2. These could be interpreted in terms of the contribution of electrophilic complexation between the aldehyde function and BF3 as a rate-limiting step. A large negative p value was observed for the complex-formation equilibria between substituted benzaldehydes and BF3.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610080108
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  • 31
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    Electronic Resource
    Control of the thermal cis to trans isomerizations of azobenzene and thioindigo derivatives by the formation of supramolecular H-bonded assemblies (1995)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 8 (1995), S. 54-62 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: 2,3-Bis(aminocyclohexyl)-6-methoxy-1,3,5-triazine (1a) forms intermolecular H-bonded complexes with 3,3′-diacetyl-cis-azoenzene (4) and 6,6′-diethoxy-cis-thioindigo (5b), (association constants K = 4.9 × 104 and 3.5 × 105 1 mol-1, respectively). The thermal cis→trans isomerization of 4b and 5b to 3,3′-diacetyl-trans-azobenzene (4a), and 6,6′-diethoxy-trans-thioindigo (5a), is inhibited in the intermolecular complex 1a-4b and 1a-5b. Molecular mechanics calculations support the formation of the intermolecular H-bonded complexes between 1a and 4b or 5b.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610080111
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  • 32
    Electronic Resource
    Electronic Resource
    Reaction of phenoxy radical with nitric oxide (1995)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 8 (1995), S. 47-53 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The associationof C6H5O with NO was studied with the cavity-ring-down method by directly monitoring the decay of C6H5O in the presence of varying, excess amounts of NO. The biomolecular rate constant determined in the temperature range 297-373 K can be effectively rate constant determined in the temperature range 297-373 K can be effectively represented by k1 = 10- 12 · 12 ± 0.24e (194±185)/r cm3 molecule-1 with a negative activation energy of 0.8 kcal mol-1 (1 kcal = 4.184 kJ). In order to understand better the mechanism of the reaction, ab initio molecular orbital calculations were also carried out at the MP4(SDQ)/6-31G* level of theory using the HF optimized geometries. The molecular structues and energetics of five C6H5N1O2 isomers were calculated. Among them, the most likely and stable association product, phenyl nitrite (C4H5ONO), was found to be 17 kal mol-1 below the reactants, C6H5O + NO. Combining the measured rate constant and the calculated equilibrium constant for the association reaction, C6H5O + NO = C6H5ONO the rate constant for the unimolecular decomposition of C6H5ONO was obtained as k-1 = 4.6 × 1015E-8580/T s-1. The relatively large frequency factor suggests that a loose transition state was involved in the reaction, akin to those of its alkyl analogs (RONO, R = CH3, C2H5, etc.).
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610080110
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  • 33
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    Electronic Resource
    Structural study on quasi-phosphonium salts containing phosphorus-oxygen, phosphorus-oxygen, phosphorus-nitrogen and phosphorus-sulphur bonds (1995)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 8 (1995), S. 41-46 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The crystal and molecular structues of six quasi-phosphonium salts containing phosphorus-heteroatom heteroatom=oxygen, sulphur or nitrogen0 bonds were determined. Comparison of the molecular parameters obtained with those available for reference structures demonstrated that the ‘double bond’ character for the P+ — Y bond decreases in the order Y = N ≫ O 〉 S.
    Additional Material: 1 Ill.
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    URL: http://dx.doi.org/10.1002/poc.610080109
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  • 34
    Electronic Resource
    Electronic Resource
    Masthead (1995)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 8 (1995) 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610080201
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  • 35
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    Electronic Resource
    Pressure and solvent effects on the kinetics of a Menshutkin reaction in aliphatic alcohols (1995)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 8 (1995), S. 63-70 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The kinetics of the Menshutkin reaction between triethylamine and iodoethane was studied at 313 K in seven primary and secondary alkanols. An accurate conductimetric method was employed to obtain second-order rate constants at pressures of 0·1-200 MPa. Volumes and isothermal compressions of activation were calculated by different model-based equations which are compared. Activation volumes at 0·1 MPa are in the range -26 to -33 cm3 mol-1. Procedures for dissecting intra- and intermolecular contributions to the volume of activation are discussed. A clear dependence of model parameters on the solvent volumetric properties was found.
    Additional Material: 1 Ill.
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    URL: http://dx.doi.org/10.1002/poc.610080202
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  • 36
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    Electronic Resource
    Oil-in-water microemulsions based on chemodegradable surfactants as reaction media (1995)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 8 (1995), S. 71-76 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The reaction of 2-(p-nitrophenyl)ethyl bromide with hydroxide ion was studied in oil-in-water (o/w) microemulsions at 50°C. The octane-in-water microemulsion systems were stabilized by chemodegradable cyclic acetal-type cationic surfactants as [(2-alky-1,3-dioxolan-4-yl)methyl]trimethylammonium bromides Ia-c (alkyl: a = n-C9H19; b = C11H23; c = C13H27) and butan-1-ol as co-surfactant. The rate constants were also determined in the corresponding aqueous micelles and in water. The hydrolytic lability of Ia-c in the microemulsion systems was achieved at 50°C by acid hydrolysis of the 1,3-dioxolane ring. Systematic synthetic studies of the dehydrobromination were performed in order to develop a preparative approach for the product separation without unfavourable process such as foaming and emulsification.
    Additional Material: 2 Ill.
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    URL: http://dx.doi.org/10.1002/poc.610080203
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    Infrared study of the proton acceptor ability of metyrapone (1995)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 8 (1995), S. 77-83 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The hydrogen bond complexes between metyrapone [methyl-1,2-di(3-pyridyl)propan-1-one] and hydroxylic proton donors (phenols, water) were investigated by infrared spectroscopy. The thermodynamic and spectroscopic data determined in carbon tetrachloride suggest that the nitrogen atom of the pyridine ring A [bonded to the C(CH3)2 group] is the main hydrogen bond interaction site. The data are compared with di-2-pyridylglyoxal complexes where the hydrogen bonds are formed on the oxygen atom of the carbonyl function. In the solid adduct of metyrapone with HCl, protonation takes place on the two nitrogen atoms of the pyridine rings. The data from this work are compared with those from chemical oxidation, which leads predominantly to the formation of mono-N-oxide A and di-N-oxide.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610080204
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    Isotherm of water sorption by human serum albumin in dioxane: Comparison with calorimetric data (1995)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 8 (1995), S. 84-88 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The dependence of the amount of water bound to human serum albumin (HSA) suspended in water-dioxane mixtures vs the equilibrium water concentration in the liquid phase was determined by the Fisher method at 298 K. The Langmuir model was used in order to describe the isotherm of the sorption of water by HSA at low water concentrations in the solvent. The calculated equilibrium constant of water adsorption (3.8 ± 0.6 l mol-1) is in good agreement with the adsorption constant obtained earlier from calorimetric data. The comparison of the determined isotherm of water sorption by HSA with the reported enthalpies of suspension formation showed that at low water concentrations in the solvent, water sorption is the only process contributing to the heat effects of the formation of the ‘protein + liquid’ heterogeneous system. From this comparison, the enthalpy of water adsorption by HSA was evaluated as -11.9 ± 1.7 kJ mol-1. At higher water concentrations in the solvent the amount of water adsorbed by HSA increased considerably. This increase in the amount of water on HSA at water activities above 0.5 is assumed to be due to the enlargement of the protein surface area.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610080205
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  • 39
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    The solvent effect on the conformational equilibria of 4-substituted cyclohexenes (1995)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 8 (1995), S. 89-93 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Conformational preferences have been measured for 4-X-cyclohexenes (X = Br, Cl, CHO, COOH) in a series of solvents with increasing polarity. The conformational equilibrium exhibits a very weak solvent dependence. ΔG varies at most by 0·25 kcal mol-1 (1 kcal = 4·184 kJ) shifting from a non-polar mixture (CS2-CDCI3) to highly polar (CD3)2SO. The reaction field theory was used to calculate the variation of ΔG with solvent polarity. The calculated solvent shifts δΔG are small and in agreement with the values determined experimentally.
    Additional Material: 2 Ill.
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    URL: http://dx.doi.org/10.1002/poc.610080206
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    A remarkably bent allene. X-Ray crystal structure and ab initio calculations (1995)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 8 (1995), S. 94-96 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: X-ray data on the crystal and molecular structure of bis(biphenyl-2,2′-diyl)allene, reveal a remarkably strong deviation from linearity (170·1°) of the allene unit of the molecule. Ab initio calculations involving dimers of molecules yield good correlation with this geometry, showing that the non-linearity is due to packing effects in the crystal.
    Additional Material: 2 Ill.
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    URL: http://dx.doi.org/10.1002/poc.610080207
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  • 41
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    Kinetics of the reaction of amines with 1,1,1-trichloro-4-methoxy-3-penten-2-one (1995)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 8 (1995), S. 97-102 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The kinetics of the reaction of 1,1,1-trichloro-4-methoxy-3-penten-2-one with various aliphatic and aromatic amines was studied at 25°C in water, dimethyl sulphoxide, methanol, ethanol, chloroform, toluene and hexane. The formation of the corresponding 1,1,1-trichloro-4-amino-3-penten-2-one is explained in terms of an addition-elimination mechanism.
    Additional Material: 1 Ill.
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    URL: http://dx.doi.org/10.1002/poc.610080208
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  • 42
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    Are kekulene, coronene, and corannulene tetraanion superaromatic? Theoretical examination using hardness indices (1995)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 8 (1995), S. 103-107 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The superaromaticity concept is examined and developed, taking into account what is known about aromaticity. Three new hardness indices indices are defined, and shown to be excellent parameters for characterizing superaromaticity. High superaromaticity indicates significant global annulenoid conjugation relative to local benzenoid conjugation in circularly annealed benzenoid molecules. Kekulene, coronene and corannulene tetraanion all are predicted to be superaromatic. The prediction for the corannulene tetraanion strongly supports the “annulene-within-an-annulene” structure derived from NMR data.
    Additional Material: 1 Ill.
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    URL: http://dx.doi.org/10.1002/poc.610080209
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  • 43
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    Enthalpies of micelle formation by hexadecyltrimethylammonium bromide in aqueous solution containing pentanol (1995)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 8 (1995), S. 108-112 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Titration calorimetric data show a dramatic change from endo- to exothermic deaggregation when pentanol-hexadecyltrimethylammonium bromide (CTAB) mixed solutions are injected into an aqueous solution containing pentanol. The results are interpreted in terms of a change in the structures of the aggregates in solution from simple CTAB micelles to mixed amphiphilic microheterogeneities when pentanol is added.
    Additional Material: 5 Ill.
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    URL: http://dx.doi.org/10.1002/poc.610080210
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    Amines as leaving groups in nucleophilic aromatic substitution reactions. III.For Part II, see Ref. 2. Hydrolysis of 1-amino-2,4-dinitrobenzenes (1995)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 8 (1995), S. 113-120 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The kinetic study of the reaction of 1-pyrrolidino-2,4-dinitrobenzene, 1-piperidino-2,4-dinitrobenzene and 1-morpholino-2,4-dinitrobenzene with NaOH in the presence and absence of the amine leaving group was carried out in aqueous solutions at 25°C, giving 2,4-dinitrophenol as the only product. A mechanism involving the formation of σ complexes by addition of HO- or the amine to the unsubstituted positions of the aromatic ring is proposed. These complexes were found to react faster than the original substrates.
    Additional Material: 3 Ill.
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    Electronic Resource
    Electronic Resource
    Masthead (1995)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 8 (1995) 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610080301
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  • 46
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    Efficient and/or selective methylation by diazomethane of alcohols, halo alcohols, glycols, amino alcohols and mercapto alcohols with the use of a proton-exchanged X-type zeolite as an acid-base bifunctional catalyst (1995)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 8 (1995), S. 121-126 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Reactions of diazomethane with butanol, allyl alcohol and β- and γ-halo alcohols led to efficient methylation (giving the corresponding methyl ethers) with the use of a proton-exchanged X-type zeolite compared with H2SO4. The reactions with propylene and isobutylene glycols using the zeolite provided regioselective methylation of the primary OH rather than the secondary or tertiary OH, whereas regioselectivity was not observed in the reactions using H2SO4. The reactions with 2-aminoethanol and 2-mercaptoethanol showed high chemoselective S-methylation and N-monomethylation, respectively, in the presence of the zeolite instead of H2SO4. The mechanism for the reactions is proposed to involve acid-base bifunctional catalysis of the zeolite in which the acidic site reacts with diazomethane to form its conjugate acid, and the nucleophilicity of OH and SH groups is enhanced by the interaction of the basic site with the proton of the groups.
    Additional Material: 2 Tab.
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    URL: http://dx.doi.org/10.1002/poc.610080212
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  • 47
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    Theoretical studies on the acid-catalysed aromatization of benzene-cis-1,2-dihydrodiolsDetermination of Reactivity by MO Theory, Part 92. For Part 91, see Reference 1. (1995)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 8 (1995), S. 127-131 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Theoretical studies on the acid-catalysed dehydration of 15-substituted dihydrodiols were carried out using the AM1 method. In agreement with the experimental results, the rate-limiting step is dehydration of the protonated diols, R+, and the o-phenol-forming pathway (path 1) is favoured both kinetically and thermodynamically over m-phenol product formation. The transition state for path 1 (TS 1) is found to be at an early position (ca 23% progress) along the reaction coordinate and a better correlation of the rate constant is obtained with σ+. Three resonance forms can exist for the benzenonium intermediate but the contribution of one form is dominant in the later TS, which resembles the cationic intermediate. The contribution of the other two, however, weakens the σ+ effect of +M subsituents. The σP correlation of the rate constant in acid solution is therefore suggestive of a later TS resembling the cationic intermediate which is stabilized by solution.
    Additional Material: 3 Tab.
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    URL: http://dx.doi.org/10.1002/poc.610080213
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  • 48
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    Several mechanisms in the elimination kinetics of ω-chlorocarboxylic acids in the gas phase (1995)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 8 (1995), S. 133-138 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The kinetics of the gas-phase pyrolysis of ω-chlorocarboxylic acids were examined in a seasoned static reaction vessel and in the presence of at least twice the amount of the free radical inhibitor cyclohexene or toluene. In conformity with the available experimental data on rate determination, these reactions proved to be unimolecular and obeyed a first-order rate law. The presence of the primary chlorine leaving group in Cl(CH2)nCOOH (n = 1-4) showed a change in mechanism from intramolecular displacement of the Cl leaving group by the acidic hydrogen of the COOH to anchimeric assistance of the carbonyl COOH to the C—Cl bond polarization in the transition state. This mechanistic consideration is nearly the same for the series of 2-, 3-, and 4-chlorobutyric acids. The chlorine atom at the 2-position of acetic, propionic and butyric acids is dehydrochlorinated through a prevailing reaction path involving a polar five-membered cyclic transition state.
    Additional Material: 9 Tab.
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    URL: http://dx.doi.org/10.1002/poc.610080302
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  • 49
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    First successful correlation of the UV spectra of three kinds of styrenes with spin-delocalization substituent constants σ. (1995)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 8 (1995), S. 143-148 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: UV spectra of 17 para-Y-substituted styrenes, 8 para-Y-substituted α-methylstyrenes and 20 para-Y-substituted α,β,β-trifluorostyrenes were measured and correlated against spin-delocalization substituent constants (σ.) with confidence levels above 99·9%.
    Additional Material: 1 Ill.
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    URL: http://dx.doi.org/10.1002/poc.610080304
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  • 50
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    Kinetic studies on the pyramidal inversion of optically active selenonium imides (1995)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 8 (1995), S. 139-142 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Kinetic studies were carried out on the thermal epimerization by pyramidal inversion of optically active (S)-(-)Se- and (R)-(+)Se-4-[(-)-menthyloxycarbonyl]phenyl(2′,4′,6′-triisopropylphenyl)selenonium-N-toluene-4″-sulphonimides (1). The first-order rate constants for the pyramidal inversion of (S)-(-)Se-1 and (R)-(+)Se-1 were determined and the activation enthalpies and entropies were calculated. A fairly large difference was found in the activation parameters between optically active (S)-(-)Se-1 and (R)-(+)Se-1, i.e. a large negative activation entropy was obtained in the case of (R)-(+)Se-1.
    Additional Material: 2 Ill.
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    URL: http://dx.doi.org/10.1002/poc.610080303
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    Nature of the highest occupied molecular orbitals of trans- and cis-bicyclo[4.1.0]hept-3-enes (1995)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 8 (1995), S. 149-158 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Photoelectron spectra of trans-bicyclo[4.1.0]hept-3-ene and two methyl derivatives, 1-3, and cis-bicyclo[4.1.0]hept-3-ene and three of its derivatives, 4-7, were measured. Ab initio molecular orbital (MO) and density functional theory (DFT) calculations were performed on these compounds. By combining the results of the experimental and computational trends, it was established that the highest occupied molecular orbitals (HOMOs) of 1-3 are the ‘twist’ bent σ bond at the fusion between the two rings whereas for 4-7 the HOMOs are the π orbital in the six-membered ring. The DFT ordering is the same as that suggested by the photoelectron spectra whereas at the MO level the HOMO always corresponds to the π orbital. The intensities of the photoelectron spectra were calculated at the DFT level and good qualitative agreement with experiment was found.
    Additional Material: 5 Ill.
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    URL: http://dx.doi.org/10.1002/poc.610080305
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    The question of pentaphenylethyl: An AM1 study (1995)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 8 (1995), S. 171-174 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Semi-empirical AM1 theoretical calculations were carried out on the pentaphenylethyl and 9-trityfluorenyl free radicals, related radicals and their precursor hydrocarbons. Previous reports of the preparation of the former radical have been questioned, although the existence of the second is on secure ground. Based on simple energy considerations, it is concluded that pentaphenylethyl should be as readily prepared. However, the acidity of the precursor hydrocarbon is considerably less than that of 9-tritylfluorene, and possible radical decomposition via dissociation to triphenylmethyl and diphenylcarbene is calculated to be more facile than the corresponding decomposition of 9-tritylfluorenyl. A previous postulation of a rapid phenyl equilibration of the pentaphenylethyl radical is shown to be untenable.
    Additional Material: 1 Ill.
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    URL: http://dx.doi.org/10.1002/poc.610080307
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    Dicarboximide-based clathrate design. Host synthesis, inclusion formation and x-ray crystal structures of a free host and of inclusion compounds with 2- and 3- methylcyclohexanone, 3-methylcyclopentanone, butyronitrile, propan-1-ol and (-)-fenchone guests (1995)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 8 (1995), S. 159-170 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Crystalline host compounds consisting of a roof-shaped dicarboxinide framework and pendant diarylethanol analogous subunits were synthesized and shown to form inclusion complexes with small organic molecules such as alcohols, amines, ketones or polar and apolar organic solvents. Clathrate efficiency and selectivity depend on the particular host structure. The crystal and molecular structures of a free host compound (2a) and inclusion compounds [2a·3-methylcyclohexanone (1 : 1), 1a·3-methylcyclopentanone (1 : 1), 1a·2-methylcyclohexanone (1 : 1), 1b·butyronitrile (1 : 1), 1b·propan-1-ol (2 : 1) and 1b·(-)-fenchone (1 : 1)] were determined by x-ray diffraction analysis. In all the structures, the hydroxyl group is involved in intramolecular hydrogen bonds and the host and guest molecules are held by lattice forces only. The channels and cavities left in the host matrix are large enough to allow disorder or high thermal displacement parameters of the guest molecules. The local packing coefficients for all guests are 0·42 on average.
    Additional Material: 5 Ill.
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    URL: http://dx.doi.org/10.1002/poc.610080306
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    Unusually large kinetic deuterium isotope effects on oxidation reactions. 1. The mechanism of hydroxide-catalysed permanganate oxidation of PhCD(CF3)OH and PhCD(CH3)OH in WaterPresented in part at the 12th IUPAC Conference on Physical Organic Chemistry, Padova, 1994. (1995)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 8 (1995), S. 186-190 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The oxidation of 1-phenyl-2,2,2-trifluoroethanol (ROH) with potassium permanganate in 0.2 M aqueous sodium hydroxide solution at 25 °C provides 2,2,2-trifluoroacetophenone as the sole product. The reaction rate constant, which was measured under pseudo-first order conditions by following the decrease in substrate concentration as a function of time, was found to be substantially smaller than previously reported. The primary kinetic deuterium isotope effect was measured as k2H/k2D = 14·7 ± 1·0. A hydrogen-transfer mechanism involving significant tunnelling is proposed. The oxidation of 1-phenylethanol under similar reaction conditions yields acetophenone as the initial product. The kinetic deuterium isotope effect was found to be k2H/k2D = 5·2 ± 0·8.
    Additional Material: 2 Ill.
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    URL: http://dx.doi.org/10.1002/poc.610080309
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    The search for the ethynylcation: Nitrosation of N,N-bis(trimethylsilyl)ynamines (1995)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 8 (1995), S. 191-194 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The reaction of bis-silylated ynamines with different nitrosyl reagents affords products derived from an electrophilic attack at the β-carbon atom and not the expected alkynyldiazonium salts.
    Additional Material: 1 Tab.
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    URL: http://dx.doi.org/10.1002/poc.610080310
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    Masthead (1995)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 8 (1995) 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610080401
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    Guest Editorial (1995)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 8 (1995), S. 195-195 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610080402
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    Introduction to living polymeriz. Living and/or controlled polymerization (1995)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 8 (1995), S. 197-207 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The effects of various imperfections such as slow initiation, termination, transfer and slow exchange on kinetics, molecular weights and polydispersities in chain growth polymerizations are simulated. The simukations demonstrate that well defined polymers polymers can be prepared in systems with chain-breaking reactions. Thus, under carefully selected conditions, non-living polyumerizations may provide controlled polymers. On the other hand, polymers with unpredictable molecular weights and broad and even polymodal molecular weight distributions can be formed in living systems without irreversible transfer and termination. In some living systems molecular weights may stay constant or even decrease with conversion. Therefore, a clear distrinction should be made between living and polymerizations.
    Additional Material: 14 Ill.
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    URL: http://dx.doi.org/10.1002/poc.610080403
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    Living carbocationic copolymerizations. I. Synthesis and characterization of isobutylene/p-methylstyrene copolymers (1995)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 8 (1995), S. 258-272 
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    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The isobutylene (IB)-p-methylstyrene (pMeSt) monomer pair readily produces by living copolymerization nearly random copolymers with up to M̄n ≈ 50,000 g mol-1 and M̄w/M̄n ≈ 1·4. The livingness of the copolymerization process and the compositional homogeneity of the copolymers have been demonstrated by the following four diagnostic plots: (A) M̄n (number-average molecular weight) and corresponding N (number of moles of copolymer formed) vs Wp (weight of copolymer formed) for the diagnosis of chaintransfer; (B) -ln (1 - C) (C = conversion of monomers) vs time for the diagnosis of termination; (C) copolymer composition vs molecular weight; and (D) cumulative copolymer composition vs conversion for the diagnosis of true homogeneous copolymers. The theory for the use of the -ln(1 - C) vs time plot for the quantitation of irreversible termination in copolymerization has been developed. The exact conditions (i.e. nature of reagents, reagent concentrations, temperature, etc.) which lead to desirable products in terms of conversion, molecular weight, molecular weight distribution (MWD) and copolymer composition, were developed systematically by analyzing the results of a large number of experiments. The following combination of chemicals was found to lead to living copolymerization, and uniform high molecular weight, narrow MWD copolymers: IB-pMeSt 97 : 3 mol/mol with 5-tert-butyl-1,3-dicumyl methyl ether (5-tBu-1,3-DiCumOMe) initiator, TiCl4 coinitiator, ethyl chloride (EtCl) solvent, triethylamine (TEA) electron pair donor (ED) and 2,6-di-tert-butylpyridine (DtBP) proton trap at -52, -65 and -85°C.
    Additional Material: 13 Ill.
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    URL: http://dx.doi.org/10.1002/poc.610080409
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    Living carbocationic copolymerizations. II. Reactivity ratios and microstructure of isobutylene/p-methylstyrene copolymers (1995)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 8 (1995), S. 273-281 
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    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A novel method was developed for the quantitative description of copolymerization behavior, specifically for the derivation of reactivity ratios and micro- and macro-compositions of monomer pairs with significantly different reactivities. The novelty of the method lies in the manner of generating instantaneous feed and copolymer composition data from experimentally readily obtainable cumulative copolymer compositions, although the latter drifts with progressing copolymerization. It is demonstrated that such copolymer systems can be described by two reactivity ratios, albeit the values are valid only over the narrow feed composition range within which they were determined. The great advantage of this method is that whereas the differential copolymer composition equation is strictly valid only at 0% conversion, the method produces corresponding instantaneous feed and copolymer compositions at any conversion. Assumptions or approximations are unnecessary to calculate reactivity ratios. Subsequently the procedure was applied to obtain reliable monomer reactivity ratios of isobutylene (IB)-p-methylstyrene (pMeSt) copolymers, rIB and rpMest, prepared by living carbocationic copolymerizations with [IB]/[pMeSt] feeds compositions of 90:10 and 97:3 mol/mol, i.e., with feed compositions of industrial importance. According to our procedure, rIB = 0·74±0·11 and rpMeSt = 7·99±3·34. These reactivity ratios were then used to calculate overall IB-pMeSt copolymer compositions over the entire comonomer conversion range and to compare calculated with experimental compositions. The good quantitative agreement between calculated and experimental compositions indicates that the description of both macro- and micro-compositions of IB-pMeSt copolymers obtained in the 90:10 and to 97:3 mol/mol feed composition range is satisfactory.
    Additional Material: 13 Ill.
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    URL: http://dx.doi.org/10.1002/poc.610080410
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    Nitroxide mediated free radical polymerization process - autopolymerization (1995)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 8 (1995), S. 301-305 
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    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The autopolymerization of styrene in the presence of TEMPO (2,2,6,6-tetramethyl-1-piperidinyloxy free radical), with and without organic acids, such as benzoic acid and camphorsulfonic acid, was studied. Broad polydispersities are obtained in the absence of acid, whereas narrower polydispersities are obtained in their presence. The significance of these results for the synthesis of narrow polydispersity polystyrene by the TEMPO-mediated living polymerization process is discussed.
    Additional Material: 5 Ill.
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    URL: http://dx.doi.org/10.1002/poc.610080413
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    Nucleophilic substitution at nitrogen-centered radicals: Reactions of diphenylphosphide ions with N,N-dibutyl-p-toluenesulfonamide by the SRN1 mechanism (1995)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 8 (1995), S. 356-358 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The photostimulated reaction of N,N-dibutyl-p-toluenesulfonamide with diphenylphosphide ions in liquid ammonia leads to the corresponding phosphinic amides after oxidation Inhibition experiments with p-dinitrobenzene and 2,2,6,6-tetramethyl-1-piperidinyloxy free radical (TEMPO) and the fact that the reaction is retarded in the dark suggest that it proceeds by the SRN1 mechanism.
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    Complexation of tropylium ions with crown ethers and acyclic polyethers examined by fast atom bombardment mass spectrometry (1995)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 8 (1995), S. 377-384 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The molecular complex formation of six macrocyclic and six acyclic polyethers with tropylium and 4-methoxyphenyltropylium tetrafluoroborates was observed and characterized in the gas phase by fast atom bombardment mass spectrometry (FABMS), to obtain information on intrinsic molecular interactions in the absence of the complicating effect of solvation. The stoichiometry of the complexes was assessed on the basis of corresponding peaks in FAB mass spectra. In addition to the expected 1 : 1 complexes between polyether and tropylium ion, some 2 : 1 complexes were also formed. The stability order of selected complexes was studied in competition experiments. The complexation equilibrium constant and thermodynamic parameters for the interaction of dibenzo-18-crown-6 with tropylium ion were determined in 1,2-dichloroethane solution by UV-visible spectrophotometry. Complexation of polyethers with tropylium salts has not been reported previously.
    Additional Material: 4 Ill.
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    Masthead (1995)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 8 (1995) 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610080601
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    Aqueous solvation effect on the prototropic tautomerism of 2-thiocytosine (1995)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 8 (1995), S. 395-399 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Free energies of solvation were calculated for the four most stable gas-phase tautomeric forms of 2-thiocytosine (TC) using a local field SCF procedure with the solvation model SM2. The calculated changes in the free energies for each pair of tautomers reveal that all six possible equilibria tend to produce the thione-amino TC(1, 8, 8) and TC(3, 8, 8) species. This is in agreement with UV and ionization constant data.
    Additional Material: 2 Ill.
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    URL: http://dx.doi.org/10.1002/poc.610080603
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    Radiolytic studies of the reductive cyclization of 2-nitroarylamides: Cyclization via hydroxylamine intermediates (1995)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 8 (1995), S. 587-596 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The reductive cyclization of several 2-nitroarylamides was studied by radiolytic reduction, examining the effects of substituents on the nitrophenyl ring and on the leaving aniline and variations in the nature of the link between the nitrophenyl ring and the leaving aniline. The stoichiometry of the reduction and the identification of N-hydroxylactam and aniline products suggest that the major initial products of such a reduction of the nitroamides are the corresponding hydroxylamines. Under anaerobic conditions, cyclization via the hydroxylamines was considerably faster (up to 160-fold) than via the corresponding amines under comparable conditions, but was similarly influenced by changes in geometry. Unlike cyclization via the amines, rates of cyclization via the hydroxylamines were sensitive to substitution on the leaving aniline, being accelerated by electron-withdrawing groups. The rate-determining step in the cyclization of the hydroxylamines is proposed to be breakdown of the tetrahedral intermediate.
    Additional Material: 4 Ill.
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  • 67
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    Mono-, bis- and tetra-acridine ligands: Synthesis, X-ray structural determination and dynamic fluorescence microscopic studies on the modification of the higher order structure of DNA (1995)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 8 (1995), S. 597-604 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A series of mono-, bis- and tetra-acridine ligands were prepared and their effects on the higher order structure of DNA were studied by dynamic fluorescence microscopy. The single-crystal structure of the bis-acridine derivative N-[2-(dimethylamino) ethyl]-4-[2-(9-acridinylamino)benzamido]-2-(9-acridinylamino)benzamide trihydrochloride (4) was determined, and shows that the molecule is sufficiently flexible to fold into an intramolecular stacking interaction in the crystal, supporting earlier hydrodynamic evidence that this compound can bis-intercalate into DNA forming a single base pair (bp) sandwich complex. The corresponding tetra-acridine analogue 1,11-bis[4-[2-(9-acridinylamino)benzamido]-2-(9-acridinylamino)phenyl]-1,11-dioxo-6-methyl-2,6,10-triazaundecane pentahydrochloride (6) was synthesized, and dynamic fluorescence microscopy was used to study the effects of 4 and 6 on the higher order structure of large T4 DNA molecules (166 kbp), by measuring the average long-axis legth (persistence length, l) of the complexes. The mono-intercalating ligand acridine orange (5) increase l, whereas the bisintercalating diacridine 4 has no apparent effect and the putative multi-intercalating tetracridine derivative 6 decreases l by compacting the higher order DNA structure. These results demonstrate the usefulness of the technique for directly observing ligand-DNA complexes, and show that ligands with suitably positioned multiple binding sites can influence the higher order structure of DNA (and thus possibly gene expression).
    Additional Material: 4 Ill.
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    Metal ion complexation by the phosphoryl and the carbonyl groups probed by 17O NMR spectroscopy (1995)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 8 (1995), S. 605-609 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Interactions between compounds containing phosphoryl, carbonyl, or hydroxyl groups (or combinations of these groups) with metal ions (Na+, Mg2+) were probed in CD3CN solutions by 17O NMR spectroscopy. For all phosphoryl and carbonyl substrates a strong high - field shift of the P=O and C=O signals was observed on the addition of a salt; no shift was observed, however, for the OH group signal, indicating that no chelation takes place in the hydroxyphosphoryl (or hydroxycarbonyl) derivatives. For 2-hydroxy-3-benzoylpropylphosphonic diester the 17O NMR studies, together with conformational analysis based on the 1H spectroscopy, demonstrated the chelation of a metal ion by the P=O and C=O functions (fermation of an eight-membered cyclic structure) with the OH group involved in the intramolecular hydrogen bonding, but not in the complexation to the metal ion.
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    URL: http://dx.doi.org/10.1002/poc.610080906
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    Aminolysis and hydrolysis of sulphamate esters: Substantial N=S bonding in the transition state leading to N=sulfonylamines (1995)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 8 (1995), S. 610-616 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The aminolysis and hydrolysis of several sulphamate esters, RNHSO2ONp (R = PhCH2, Ph, 4-MeC6H44, 3-MeC6H4, 4-FC6H4, 4-ClC6H4, 3-ClC6H4, H; Np = 4-NO2C6H4) were been studied in 50% (v/v) aqueous acetonitrile at various temperatures. Reaction of the esters with an amine (R1NH2) gives -ONp and both sulphamide, (RNHSO2NHR1) and sulphamate (RNHSO2O-R1NH3+) products. First-order rates were determined by the appearance of -ONp and sometimes also by the disapperance of ester. The reaction was found to be independent of amine type and concentration and at the high pHs that obtain the substrate esters are fully ionized. A Hammett ρacyl of -;1·8 was obtained for the decomposition of the sulphamate anions and this is consistent with substantial N=S bonding in the transition state leading to N-sulphonylamine, RN=SO2. This intermediate then partitions very rapidly, reacting with R1NH2 and H2O respectively. ΔH
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    Kinetics and mechanism of reaction of acridine orange with bromateion at low pH (1995)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 8 (1995), S. 175-185 
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    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The reaction between acridine orange hydrochloride [3,6-bis(dimethylamino)acridine hydrochloride] and potassium bromate in dilute sulphuric acid was studied by monitoring the absorbance change at 492 nm. The reaction exhibited complex kinetic behaviour. In excess bromate the reaction had an induction period with slow depletion of acridine orange (AC) followed by a fast depletion step. The initial reaction step was found to be first order with respect to both AC and bromate and second order with respect to H+. The stoichiometric ratio of AC to bromate was 3 : 2. At the end of the induction period, the redox potential of the reaction mixture has shown a distinct rise, while the Br- concentration dropped sharply. The dual role of bromide ion both as an inhibitor and autocatalyst is discussed. A 16-step reaction mechanism is proposed and the simulated curves agreed well with the kinetic curves.
    Additional Material: 11 Ill.
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    URL: http://dx.doi.org/10.1002/poc.610080308
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    Living cationic polymerization of isobutyl vinyl ether by the CF3CO2H-SnCl4-nBu4NCl system: In situ direct analysis of the growing species by 1H, 13C and 19F NMR spectroscopyThis work was presented in part at the 42nd Annual Meeting of the Society of Polymer Science, Tokyo, Japan, September 1993, paper 20D151 and at the International Conference on Frontiers in Polymerization, Liège, Belgium, October 1993.2 (1995)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 8 (1995), S. 282-292 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Direct 1H, 13C and 19F NMR spectroscopic analysis was carried out on the carbocationic intermediate generated in the interaction of tin(IV) chloride (SnCl4) with the adduct [4, CH3CH(OiBu)OCOCF3] of isobutyl vinyl ether (IBVE) and trifluoroacetic acid (CF3CO2H), either in the presence or in the absence of tetrabutylammonium chloride. The reactions were to mimic the living cationic polymerization of IBVE by the 4-SnCl4 initiating system (with added nBu4NCl) that was also found in this study. In CD2Cl2 solvent at -78°C, the 1H and 13C NMR analysis revealed the formation of a carbocationic intermediate [CH3C+H(OiBu)] that is in a rapid exchange equilibrium with the covalent counterpart 4. For the first time, the cation formation was further supported by 19F NMR analysis on the counteranionic part (CF3COO-) in 4, where, with SnCl4, the CF3 group gave a broadened signal that appeared clearly downfield relative to that in the covalent form. These and other results, which are in close correlation with the corresponding polymerizations, demonstrated the following: (i) the SnCl4-assisted generation of carbocationic species from the covalent ester 4; (ii) a rapid exchange between the cation and its covalent precursor 4; (iii) the relatively high cationic concentration in the salt-free system, where no living polymerization occurs; and (iv) the effective suppression of the cationic species in the presence of the salt, which proved to be the prime key factor for living polymerization.
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    Nature and concentration of active species in cationic polymerization of vinyl ethers: A kinetic investigation (1995)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 8 (1995), S. 293-300 
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    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The Kinetics of the polymerization of isopropyl vinyl ether, isobutyl vinyl ether (IBVE) and chloroethyl vinyl ether initiated by HI in CH2Cl2, in the presence and in the absence of tetrabutylammonium iodide as common anion salt, were investigated. The polymerizations proceed directly through the carbon-iodide termini without any necessary electrophilic activator. As previously observed with cyclohexyl vinyl ether, it was found that the addition of small amounts of salt, (0·5-10% with respect to initial [HI], depending on the monomer) drastically reduces the polymerization rate and leads to living-type polymerizations. Higher amounts of salt have no influence on the polymerization rate which remains constant over a broad range of [NBu4I]/[HI] ratios. This general behaviour, observed for the all vinyl ethers, suggests a common ion salt effect and therefore an ionic polymerization mechanism involving ion pairs and free ions. In the absence of salt, both ion pairs and free ions of higher reactivity participate in the propagation, whereas only ion pairs contribute to the propagation in the presence of a common ion salt. According to this scheme, the living character of the polymerization is assumed to result from a propagation reaction governed by undissociated ionic species. The validity and the implications of this reaction scheme, in terms of active centre concentrations, are also discussed.
    Additional Material: 5 Ill.
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    URL: http://dx.doi.org/10.1002/poc.610080412
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    Masthead (1995)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 8 (1995) 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610080501
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    Polymerization of acrylates and methacrylates to make homopolmers and block copolymers initiated by N-alkoxyphthalimides and succinimides (1995)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 8 (1995), S. 316-324 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Various N-alkoxyphthalimides were prepared and tested as initiators for polymerization of a variety of monomers. Acrylates and methacrylates polymerized at 40-50°C. Vinyl acetate and styrene were moderately reactive at 60-65°C. Rates of reaction were sensitive to the choice of solvent. THF generally gave the highest conversions, with much reduced reactivities in solvents of higher polarity, such as acetonitrile, acetone, DMSO or DMF. In aliphatic hydrocarbon solvents or di-n-butyl ether no polymers were obtained. Bulk polymerizations proceeded well, depending on the monomer. Rates of polymerization were sensitive to the structure of the group attached to nitrogen. OR groups, where R contained α-electron-withdrawing esters, benzylic or allylic groups, were more reactive than when R was an aliphatic group. A-B block copolymers were readily prepared, starting with PMA, PBA or PMMA. However, because the rates of initiation were slow, relative to rates of propagation, N-alkoxyphthalimide initiators survived mostly intact. Consequently, final A-B block copolymers were invariably contaminated with indeterminate amounts of homopolymer from polymerization of the second monomer.
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    Theoretical studies on the reactions of substituted phenolate anions with formate estersDetermination of Reactivity by MO Theory. Part 91. For Part 90, see Ref. 1. (1995)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 8 (1995), S. 325-334 
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    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Semiempirical MO (PM3) studies are reported on the reactions of 18 substituted phenolate anions with m-(MNPF), p-(PNPF) and 3,4-dinitrophenyl formates (DNPF). The mechanistic change from rate-limiting formation to breakdown of the anionic intermediate (T-) can occur in the gas phase, especially for MNPF, at approximately an equal proton affinity (PA) of the nucleophile and leaving group phenolates, i.e. ΔPA = 0 as the PA of the phenolate anion is decreased. In solution, however, owing to the low stability of T and a greater stabilization by solvation of the transition state for the breakdown step (TS2), all three formate esters are predicted to proceed by a concerted mechanism, which is in agreement with the experimental results. The low stability of T can be ascribed to the relatively high electron affinity of the phenolate anions.
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    URL: http://dx.doi.org/10.1002/poc.610080502
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    Oscillations of electrical potential differences across the interface in phase-transfer catalytic systems (1995)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 8 (1995), S. 341-343 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Oscillations of electrical potential differences across the liquid-liquid interface in phase-transfer catalyst systems are reported. The occurrence of the oscillations is consistent with the Starks' shuttling mechanism.
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    URL: http://dx.doi.org/10.1002/poc.610080504
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    Complexation of spiropyrans with cyclodextrins: Effects of β- and γ-cyclodextrins on the thermal isomerization of 6-SO3--spiropyran (1995)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 8 (1995), S. 335-340 
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    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The thermal isomerizations of 1′,3′,3′-trimethyl-spiro[2H-1-benzopyran-2,2′-indoline]-6-sulphonic acid (6-SO3--SP) between its spiro (SP) and merocyanine (MC) forms were followed spectrophotometrically in the presence of cyclodextrins (β- and γ-CDs) at various pressures. From the pressure dependence of the isomerization rate, the activation volumes for the thermal isomerization of 6-SO3--SP were estimated to be 17·1 cm3 mol-1 for MC → SP and 8·5 cm3 mol-1 for SP → MC. The equilibrium constants (K) for the inclusion complex formation of CDs with 6-SO3--SP were determined at various pressures. It was found that the stability of the 1:1 inclusion complex between 6-SO3--SP and CDs decreases in the order β- 〉 γ- 〉 α-CD. From the pressure dependence of K, the reaction volumes were estimated to be -0·9 cm3 mol-1 for the 6-SO3--SP-β-CD system and 4·0 cm3 mol-1 for the 6-SO3--SP-γ-CD system. Based on the activation volumes, the structure of the transition state for the thermal isomerization is discussed and an explanation for the effect of CDs on the reaction rate is given. The difference in the reaction volumes for the inclusion complex formation of β- and γ-CDs is explained in terms of the difference in the number of water molecules excluded from the CD cavity.
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    URL: http://dx.doi.org/10.1002/poc.610080503
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    Mechanism of bimolecular substitution reactions of hydroximoyl halides with amines in actonitrile solution (1995)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 8 (1995), S. 344-350 
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    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The reaction in acetonitrile solution of (Z)-O-methylbenzohydroximol chlorides [ArC (Cl)=NOCH3] with morpholine, pyrrolidine and azetidine gives the corresponding (Z)-amidoximes [ArC(NR1R2)=NOCH3] in acetonitrile. The rates of these reactions were measured under pseudo-first-order conditions (excess amine). The reactions were found to follow overall second-order kinetics (first order in amine). The Hammett ρ-value (with σ) for the reaction with pyrrolidine is +0·92. The reaction of the p-nitro compound with pyrrolidine gives a significant element effect [k(p-nitrobenzohydroximoyl bromide)/k(p)-nitrobenzohydroximoyl chloride = 10]. A Brφonsted β-value of 0·38 was estimated from the reactions of morpholine and piperidine with the p-nitrohydroximoyl chloride. The slower reaction of (E)-O-methyl-p-nitrobenzohydroximoyl chloride with azetidine gives primarily the (E)-amidoxime (E:Z ≈ 98:2) This reaction also follows second-order kinetics. The kinetic observations made in this study are compared with the corresponding results obtained in earlier work in benzene solution. It is suggested that in acetonitrile solution the reactions proceed by an addition-elimination mechanism with rate-determining loss of chloride ion (AN + DN#). It is further suggested that acetonitrile is assisting in the breakdown of the tetrahedral intermediates formed in these reactions.
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    URL: http://dx.doi.org/10.1002/poc.610080505
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    Solution electron affinity changes via the deuteriation of the methyl groups of p-xylene (1995)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 8 (1995), S. 371-376 
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    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: EPR techniques, including spectral double integration, were utilized to measure the equilibrium contants in dimethoxyethane at 195 K for electron transfer between perdeuteriated p-xylene and xylene, α-d3-p-xylene and α,α′-d6-p-xylene. The results, coupled with the law of Hess, yield all the relative solution electron affinities (EA). It was found that methyl deuteriation lowers the solution EA by 160 J l mol-1 per deuterium, whereas ring deuteriation in these systems lowers the solution EA by about 370 J l mol-1 per deuterium, which is about the same effect as is observed in the benzene system. The results are discussed in terms of hyperconjugative, inductive and solvation effects.
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    URL: http://dx.doi.org/10.1002/poc.610080510
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    Correction (1995)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 8 (1995), S. 385-385 
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    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610080512
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    Kinetic study of proton/deuteron transfer reactions of 2,4,6-trinitrotoluene and its derivatives with tertiary amines (1995)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 8 (1995), S. 387-394 
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    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The rate of proton/deuteron transfer reactions of 2,4,6-trinitrotoluene (TNT), 2,2′4,4′6,6′-hexanitrobibenzyl (HNBB) and 2,4,6-trinitrobenzyl chlorides (TNB) with tertiary amines was followed spectrophotometrically. The rate constants obtained under various conditions were interpreted in terms of isotope, solvent and steric effects. The Arrhenius plots curved upward at low temperatures for TNT and TNB, indicating clearly the intervention of tunnelling. The tunnelling parameteres were calculated semi-empirically on the basis of Bell's theory. The observed rate constants at low temperatures agreed well with the predicted values. In the present systems, some side and consecutive reactions involving the formation of 2,2′,4,4′6,6′-hexanitrostilbene took place, and in some cases interrupted the rate measurements in the proton/deuteron transfer steps.
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    URL: http://dx.doi.org/10.1002/poc.610080602
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    Prediction of hydrogen bond basicity in nitriles from dipole moments, mesomeric effects and electrostatic potentials (1995)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 8 (1995), S. 421-428 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Measured molecular dipole moments and theoretical percentages of mesomeric zwitterionic forms were used to calculate the attractive electrostatic potentials at short, V(s), medium, V(m), and long, V(I), distances. Values of an attraction power function Φ (H) = A + BV (s) V(m) V(I) was then deduced for 18 nitriles and cyanamide vinylogues or iminologues along the C≡N direction. The satisfactory agreement observed between Φ (H) and the hydrogen bond basicity scale pKHB indicates that the method can be a useful tool for the prediction of hydrogen bonding, needing only simple calculations and allowing easy interpretation.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610080606
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    Kinetics and mechanism of oxidation of (arylthio)acetic acids by pyridinium hydrobromide perbromide (1995)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 8 (1995), S. 429-434 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Oxidation of several monosubstituted (phenylthio)acetic acids (PTAA) by pyridinium hydrobromide perbromide (PHPB) was studied in aqueous acetic acid. The reaction is first order with respect to PHPB. Michaelis-Menten type kinetics are observed with respect to (arylthio)acetic acid. The effect of solvent composition indicates that the transition state is more polar than the reactants. The formation constants of the intermediate substrate-PHPB complexes and the rates of their decomposition were determined at different temperatures. The rates of oxidation of para and meta-substituted (phenylthio)acetic acids were correlated with Hammett's substituent constants. The ρ value is -1·60 at 35°C. The rates of oxidation of ortho substituted compounds are correlated with Charton's triparametric equation. A mechanism involving the decomposition of the intermediate complex in the slow rate-determining step affording a sulphonium ion which hydrolyses in a subsequent fast step to the sulphoxide is proposed.
    Additional Material: 6 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610080607
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  • 84
    Electronic Resource
    Electronic Resource
    Ab initio molecular orbital study of the O + C6H5O reaction (1995)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 8 (1995), S. 407-420 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: An ab initio molecular orbital study of the potential energy surface of the C6H5O + O reaction was performed at the (PUMP3/6-31G*//UHF/6-31G*) level of theory. Various reaction channels were considered. The most favorable mechanism, la and Ib, start from the attachment of the oxygen atom to the carbon atom of the C6 ring in the ortho- or para position with respect to CO, taking place without activation energy. Then, either hydrogen elimination by mechanism Ia or 1,2-H shift from the C(H)(O) group takes place; the latter process leads to the formation of the very stable C6H4(O)(OH) radical, which can also eliminate H by mechanism Ib. Thus, the main products of the C6H5O (2B1) + O(3P) reaction are o/p-benzoquinones and the hydrogen atom. At low temperatures, however, the system may be trapped in the potential well of the C6H4(O)(OH) intermediate. At high temperatures, the reaction may proceed by the formation and decomposition of o/p-benzoquinones. Because of their higher activation energies, the reaction mechanisms giving rise to other products-the attachment of the oxygen atom to the bridging position to form an epoxy intermediate, followed by insertion of O into the CC bond and dissociation to give C5H5 and CO2 (channel IIc), in addition to the attachment of oxygen to the terminal O atom of C6H5O followed by elimination of O2 (channel III) - cannot compete with channel Ia or Ib. RRKM calculation was carried out for the total and individual rate constants for channels Ia and Ib. The three-parameter expression for the total rate constant, fitted by the least-squares method for the temperature range of 300-3000 K, is given as ktot = 5·52×10-17 T1·38 e+148/T cm3 mol-1 s-1.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610080605
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  • 85
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    Multinuclear, variable-temperature NMR study of hydrogen bonding in two ortho-Mannich bases (1995)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 8 (1995), S. 463-467 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: 1H and 13C NMR data for 2-diethylaminomethyl-3,4,6-tri- and -tetrachlorophenols in CH2Cl2 solutions at a variety of temperatures are reported. The results are consistent with intramolecular hydrogen bonding and proton transfer as shown in the structure 3. Concentration dependence of the NMR data for the perchloro compound shows an additional hydrogen bonding process attributed to the solute self-association. The 1H, 13C and 15N NMR data support the proposed proton transfer structure.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610080704
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  • 86
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    Effects of the ring size and solvent polarity on the stability of the cyclic intramolecular excimer of saturated diamines (1995)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 8 (1995), S. 484-489 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The fluorescence of some aliphatic diamines was studied in the gas phase and in some solvents at several temperatures. It was found that N,N,N′,N′-tetramethylpropane-1,3-diamine (TMPD) and N,N,N′,N′-tetramethylbutane-1,4-diamine (TMBD) have two emission bands in the gas phase. TMBD also shows two bands in solution. These bands were assigned previously to an excited monomer and an intramolecular excimer. From the temperature dependence of the intensity ratio of the two bands, the enthalpy changes for the excimer formation were evaluated. The stability of the cyclic excimer is discussed in terms of the ring size effect and the solvent effect on the band positions.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610080707
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  • 87
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    Solvent dependent difference in pKHB+ behaviour in N-methylaniline and N-phenylhydroxylamine (1995)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 8 (1995), S. 490-495 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The pKBH+ values of the conjugate acids of N-phenylhydroxylamines change drastically when the pKBH+ values are determined in dimethyl sulfoxide (DMSO) rather than methanol. The Hammett ρ values change from -5·69 to -1·20 on going from methanol to DMSO for protonated N-phenylhydroxylamines, in contrast to a shift of -4·70 to -4·83 for protonated N-methylanilines in the same two solvents. This large change in susceptibility indicates that the species from which the proton departs is not the same for protonated N-phenylhydroxylamines in the two solvents. Experimental and computational evidence supports ionization of the H+ from the O atom for the protonated N-phenylhydroxylamines in DMSO.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610080708
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  • 88
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    Structure-reactivity correlations for aza-arenes. Proton affinities, pKa values, hydrogen-deuterium exchange rates and radical-induced 13C shifts (1995)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 8 (1995), S. 496-505 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Molecular reactivity parameters based on the concept of an effective electronic potential and defined as a simple function of the molecular charge distribution were applied in a study of various aspects of the chemical reactivity of azabenzenes and azanaphthalenes. Excellent linear correlations were obtained for proton affinities, pKa values, H-D exchange rate exponents and 13C shifts induced by the paramagnetic shift reagent TEMPO. In the last case, the predictions for quinazoline prompted a reinvestigation of the 13C NMR spectrum of this compound, resulting in a reassignment of the spectrum relative to the assignment assumed by Grant and co-workers.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610080709
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  • 89
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    Atomic force microscopy and Solid-State rearrangement of benzopinacol (1995)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 8 (1995), S. 545-551 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The solid-solid chemical reaction of benzopinacol (1) with p-toluenesulphonic acid monohydrate (2) to give a quantitatively proton-catalysed pinacol rearrangement with formation of triphenylacetophenone (3) in the absence of a solvent was studied preparatively and mechanistically using atomic force microscopy (AFM) measurements and known crystal structure data. The reaction rate is dramatically enhanced if the water of reaction is continuously removed. AFM reveals that no reaction occurs on (001) of 1 whereas (100) exhibits distance dependent craters and volcano-like mounds over areas extending to 1·5 mm from the contact edge of the crystals with 1 undergoing phase rebuilding while reacting. A mechanism resembling the formation of membrane potentials is seen for the first time in crystals. Thus it appears that catalytic protons migrate without their counterions from one molecular compartment to the next by proton consumption at its inside and proton liberation at its outside, which is the inside of the next compartment. The uppermost molecular layer determines reactivity or non-reactivity. On (001) of 1 the hydroxyl groups occur with their hydrogens up. Hence no AFM features are found and crystals of 2 do not become adhered to 1. However, on (100) the hydroxyl hydrogens point down (free electron pair up). Protonation is possible, chemical reaction is indicated by the formation of the AFM features and crystals of 2 adhere firmly to the surface of 1 after reaction.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610080805
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  • 90
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    Equilibrium of α-aminoacetonitrile formation from formaldehyde, hydrogen cyanide and ammonia in aqueous solution: Industrial and prebiotic significance (1995)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 8 (1995), S. 721-730 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The equilibrium constant, Kan(H2CO), for the formation of α-aminoacetonitrile from formaldehyde, ammonia and hydrogen cyanide was evaluated at 25°C. A first estimation of Kan(H2CO) was obtained from extrathermodynamic relationships of the type log K′ vs ∑σ*. The final value was then obtained from a comparison of the experimental and calculated pH dependences of α-hydroxy- and α-aminoacetonitrile concentrations. From these results, it appears that, after equilibrium, the ratio between the concentrations of the two precursors glycine and hydroxyethanoic acid, is a linear function of the concentration of free ammonia, i.e. [CH2(OH)CN] [CH2(NH2)CN] = 21 [NH3] at 25°C.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610081105
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  • 91
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    Ab initio study of the low reactivity of thiophene in Diels-Alder reactions with carbon dienophiles (1995)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 8 (1995), S. 753-760 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The utility of thiophene as a diene for Diels-Alder reactions was studied by ab initio methods. The reactivity was evaluated with three dienophiles, vinyl alcohol, ethylene and acrylonitrile. Qualitatively the reactivity was determined by comparison of the reactant's frontier orbital energies, bond orders and charge transfer in the transition states. Quantitatively the reactivity was determined by estimation of activation energy with RHF/6-31G*, MP2/6-31G*, MP3/6-31G*//MP2/6-31G*, and MP4/6-31G//MP2/6-31G* ab initio calculations. The results of the calculations predicts that the reactivity of thiophene with acrylonitrile is similar to butadiene and ethylene with a preferred formation of the endo isomer.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610081109
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  • 92
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    Masthead (1995)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 8 (1995) 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610081201
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  • 93
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    Chiral polymethine dyes: A remarkable but forgotten conjugated π system (1995)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 8 (1995), S. 761-773 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Chiral polymethine dyes constitute a particular class of conjugated π systems. Artificial chiral polymethine dyes were first synthesized by König and Langbein in 1928 in order to clarify the electronic structure of cyanine dyes; some natural dyes such as musca-aurin I (from the toadstool fly agaric) and betanin (from the vegetable red beets) are known to be chiral pentamethinium cyanine dyes, the chirality of which stems from L-α-amino acids as end-groups. The reasons why chiral polymethine dyes are not only of historical interest but once again the subject of research are explained.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610081202
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  • 94
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    Antioxidant synergism and mutual protection of α-tocopherol and β-carotene in the inhibition of radical-initiated peroxidation of linoleic acid in solution (1995)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 8 (1995), S. 774-780 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Peroxidation of linoleic acid was initiated by azobis(isobutyronitrile) in tert-butyl alcohol and inhibited by α-tocopherol, β-carotene and retinal, either alone or in combination. Significant antioxidant synergism and a novel mutual protection of α-tocopherol and β-carotene were found and the possible involvement of retinal in the process is discussed.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610081203
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  • 95
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    Mechanistic aspects of ‘ligated’ anionic living polymerization (LAP): The case of (meth)acrylic ester monomers (1995)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 8 (1995), S. 208-221 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The recently developed ‘ligated’ technique has proved to be very successful in promoting living anionic polymerization of (meth) acrylic ester monomers. The efficient ligands discovered to date include μ, σ and μ-σ dual types. The roles of these ligands in the control of livingness and stereoregularity of anionic polymerization of (meth) acrylates are discussed in detail. There is convincing evidences that both ligation thermodynamics (electron density redistribution and steric hindrance in the formed active complex) and kinetics (how fast and in which way ligation occurs) are very critical in promoting the livingness. Moreover, steric hindrance appears to be a determining factor maintaining the process ‘living’ under more demanding conditions.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610080404
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  • 96
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    Synthetic and mechanistic aspects of anionic polymerization of (METH)acrylates initiated by metal-free salts of CH-acidic compounds (1995)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 8 (1995), S. 231-241 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The tetrabutylammonium salts of CH-acidic compounds (malonic acid diesters and diamides, nitropropane, phenylacetic and phenylpropionic acid esters and 9-ethyltfuorene) serve as inexpensive initiators for the anionic polymerization of acrylates and methacrylates at room temperature. Molecular weights of 1500-25,000 can be reached, the molecular weight distributions being fairly narrow (D = 1·1-1·4 in optimized cases). Side-reactions as monitored by GC analyses include backbiting and Hofmann elimination, which means that the process is not a true living polymerization. The x-ray structural analyses of the tetrabutylammonium salts of phenylacetic and 2-phenylpropionic and 2-phenylbutyric acid esters show that anions and cations interact with one another via hydrogen bonding. Therefore, the initiators cannot be considered to be naked anions, a conclusin which very likely also applies to the growing polymer chain end during polymerization.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610080406
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  • 97
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    Stereochemical control in anionic polymerization of 2-vinylpyridine and related vinyl monomers (1995)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 8 (1995), S. 222-230 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The alkylation, silylation and other electrophilic reactions of 1-lithio-1,3-bis(2-pyridyl)butane (2a) in THF at -78°C leads to meso-like products that may be accounted for by intramolecular coordination of Li ion with the penultimate 2-pyridyl group. This is also demonstrated by proton-transfer equilibria between 1-lithio-2-ethylpyridine and 2a, allowing the determination of the ΔH and ΔS of intramolecular chelation in 2a. The ΔS of chelation is nearly zero, probably as a result of chelation-induced desolvation of Li ion. Surprisingly, however, the corresponding addition of 2-vinylpyridine to 2a and higher P2VPLi homologs in THF is not stereoselective. In toluene at -78°C the t-BuLi-initiated polymerization of 2-VP is actually somewhat syndiotactic (rr = 0·44). The presence in this polymerization of at least one equivalent of t-BuOLi or other tertiary ROLi surprisingly leads to isotactic P2VP. SEC viscometric and other studies indicate that both the P2VPLi- and P2VPLi-ROLi complexes are monomeric in toluene. The stereochemistry is apparently due to a 1 : 1 P2VPLi-ROLi complex that discriminates between the two pro-chiral faces of the anion by preferntial coordination of the (ROLi2) moiety to the meso-prochiral face. Isotactic-like addition now occurs by electrophilic attack of 2-VP that is syn with respect to the (ROLi2) ‘counter ion.’
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610080405
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  • 98
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    Mechanistic aspects of silicon-mediated polymerization (group transfer polymerization) of methyl methacrylate with ester enolate anions as nucleophilic catalysts (1995)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 8 (1995), S. 242-248 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The role of ester enolate anions in silicon-mediated polymerization (group transfer polymerization) of methyl methacrylate (MMA) was investigated using cesium, tetrabutylammonium and lithium salts of 9-methylfluorenide as the nucleophilic catalysts. The results of normal anionic polymerization of MMA using these carbanion salts were compared directly with those of analogous GTP procedures with these carbanions in the presence of the silyl ketene acetal initiator 1-methoxy-1-(trimethylsiloxy)-2-methylprop-1-ene (MTS). In the absence of MTS these reactions are characterized by low conversions (14-52%), no control of Mn and broad molecular weight distributions. In the presence of MTS, controlled MMA polymerization is observed with molecular weights calculated based on the moles of MTS and not fluorenide anion. The MMA stereochemistry was also determined for both anionic polymerization and GTP for the same counter ions (tetrabutylammonium, cesium, lithium); within experimental error, the triad tacticities are the same for anionic polymerization and GTP. It is concluded that these results are consistent with the ester enolate anions as propagating intermediates in nucleophile-catalyzed GTP. These results are consistent with an associative GTP mechanism only if it is postulated that the chemistry and stereochemistry of a pentacovalent siliconate anion are the same as those of an ester enolate anion intermediate.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610080407
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  • 99
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    Living polymerization of methacrylic esters with aluminium porphyrin initiators. Axial ligand exchange activities of alkyl- and enolate-aluminium porphyrins in relation to the polymerization Mechanism (1995)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 8 (1995), S. 249-257 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Polymerization of methacrylic esters such as benzyl methacrylate using as initiator an-equimolar mixture of methylaluminium 5,10,15,20-tetraphenylporphine [(TPP)AlMe] and 2,7,12,17-tetramethyl-3,8,13,18-tetramethylporphine [(EtioP)AlMe] proceeded from both initiators, affording a unimodal polymer of narrow molecular weight distribution, although the reactivities of (TPP)AlMe and (EtioP)AlMe are very different from each other. 1H NMR studies on a mixture of two different (porphinato)aluminium enolates, the growing species, and a mixture of a (porphinato)aluminium enolate and an alcoholate, in the absence and presence of methyl methacrylate (MMA or MMA-d8), indicated an acyclic transition state polymerization mechanism by the participation of two aluminium porphyrin molecules, where the growing species always exchange their enolate ligands whenever it grows.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610080408
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  • 100
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    ‘Living’ and controlled radical polymerization (1995)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 8 (1995), S. 306-315 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Radical polymerizations cannot truly be ‘living’ because of the inevitable termination between growing radicals. However, relatively good control of molecular weights, polydispersities and terminal functionalities can be achieved by using either unimolecular or bimolecular exchange between growing radicals and dormant chains. The dormant chains can be in the form of either covalent species or organometallic compounds. Some systems based on alkoxyamines, organochromium compounds, organoaluminum compounds and alkyl iodides were studied and are discussed in detail.
    Additional Material: 14 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610080414
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