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  • 1
    Electronic Resource
    Electronic Resource
    Enantiomeric separation and recognition mechanism of 2-arylpropionic acid derivatives by high-performance liquid chromatography using a chiral column (1995)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 7 (1995), S. 28-33 
    Details
    ISSN: 0899-0042
    Keywords: ibuprofen ; loxoprofen ; CS-670 ; loxoprofen and CS-670 trans-alcohols ; enantiomer ; diastereoisomer ; chiral HPLC ; chiral recognition ; NMR ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: An optical resolution of the amide derivatives of ibuprofen and the carbamate-alkylester derivatives of the trans-alcohol metabolite of loxoprofen and an analogous compound, CS-670, was studied by chiral high-performance liquid chromatography (HPLC). The chiral columns SUMIPAX OA-4000 and OA-4100 were used to investigate the enantiomeric separation behavior of these derivatives using both reversed and normal mobile phases. A better separation factor (α) of the amide and the carbamate ester derivatives was obtained in the normal mobile phase than in the reversed mobile phase HPLC. In addition, the recognition mechanisms of both amide and carbamate ester enantiomers were investigated by 1H-nuclear magnetic resonance (NMR). It is suggested that the important driving forces for the enantiomeric separation are the formation of hydrogen bonding and the charge transfer complex between these derivatives and an active site of the chiral stationary phase. © 1995 Wiley-Liss, Inc.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530070106
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  • 2
    Electronic Resource
    Electronic Resource
    Ideal enantiomeric resolution by recrystallization of a racemic compound (part 4): Relationship between enantiomeric resolution phenomenon and crystal properties (1997)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 9 (1997), S. 220-224 
    Details
    ISSN: 0899-0042
    Keywords: racemic compound crystal ; mixed crystal of (+) and (-) enantiomers ; enantiomeric enrichment in solution ; reversal of chirality ; X-ray powder diffraction ; chiral sulfonium sulfonate ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A new example of a racemate showing unusual enantiomeric resolution phenomenon, in which simple recrystallization of the racemate leads to remarkable enantiomeric enrichment of either enantiomer up to 100% ee in the mother liquor, has been found. This compound is (±)-[2-[4-(3-ethoxy-2-hydroxypropoxy)phenylcarbamoyl]-ethyl]dimethylsulfonium p-nitrobenzenesulfonate [EtOCH2CH(OH)CH2OC6H4NHCOCH2CH2SMe2+O2NC6H4SO3-] [(±)-SN]. By repeating recrystallization of (±)-SN and the resulting deposited crystals successively and collecting the resulting enantiomerically enriched mother liquors with the same chirality sense, highly efficient enantiomeric resolution of the racemate into its separate enantiomers has been accomplished. The relationship between the occurrence of this enantiomeric resolution phenomenon and the crystal properties has been investigated with respect to SN and its aryl- and alkylsulfonate derivatives. The mode of enantiomeric resolution of (±)-SN was similar to that of para-substituted benzenesulfonate derivatives (±)-ST (4-MeC6H4SO3-) and (±)-SC (4-ClC6H4SO3-) previously reported, whereas the unsubstituted derivative (±)-SB (C6H5SO3-) and alkysulfonate derivatives (±)-SO (n-C8H17SO3-) and (±)-SM (CH3SO3-) did not show such an enantiomeric resolution phenomenon. The crystalline form of the former racemates that underwent the enantiomeric resolution was racemic compounds, while the latter were mixed crystals (solid solutions) composed of the respective optical antipodes. Chirality 9:220-224, 1997. © 1997 Wiley-Liss, Inc.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Chemical form of arsenic compounds and distribution of their concentrations in the atmosphere (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Applied Organometallic Chemistry 4 (1990), S. 223-230 
    Details
    ISSN: 0268-2605
    Keywords: Hydride generation ; atomic absorption spectrophotometry ; arsenic ; monomethylarsonic acid ; dimethylarsinic acid ; trimethylarsine oxide ; environment ; marine atmosphere ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In order to understand the chemical form of arsenic compounds and their distribution in unpoluted areas, concentrations of arsenic compounds in the marine atmosphere were measured in several islands in several oceans. Furthermore, concentration of arsenic compounds were also measured between Tokyo and the Syowa station during a cruise by the Antarctic observation boat Shirase. Aerosols in the marine atmosphere were collected by a high-volume air sampler with a quartz fiber filter. After extracting a sample, an analysis of arsenic compounds in the sample solution was carried out by hydride generation atomic absorption spectrophotometry combined with a cold trap of liquid nitrogen. This technique has a high analytical sensivity, so that it is suitable to determine arsenic compounds at trace level.The atmospheric concentrations of arsenic compounds were at the same level over the Pacific Ocean and the Atlantic Ocean. The concentration range of arsenic compounds over these oceans was 100-200 pg m-3 for inorganic arsenic, 10-20 pg m-3 for inorganic arsenic. It is considered that these values are the background concentrations in the northern hemisphere. On the other hand, over he Antarctic Ocean in the southern hemisphere, the atmospheric concentrations of inorganic arsenic were very low, and organic arsenics were little found. This fact indicates that arsenic in the atmosphere is strongly influenced by anthropogenic sources.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aoc.590040308
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  • 4
    Electronic Resource
    Electronic Resource
    Studies on the Constituents of the Leaves of Tinospora tuberculata, I. - Isolation and Structure Elucidation of two New Furanoid Diterpenes, Tinotufolin A and B (1993)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1993 (1993), S. 325-327 
    Details
    ISSN: 0170-2041
    Keywords: Tinospora tuberculata ; Menispermaceae ; Tinotufolin A and B ; Diterpenes ; Terpenes ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Two new furanoid diterpenes, tinotufolin A (1) and B (2) were isolated from the fresh leaves of Tinospora tuberculata Beumée (Menispermaceae). The structures of 1 and 2 were elucidated on the basis of chemical and spectroscopic findings.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.199319930154
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  • 5
    Electronic Resource
    Electronic Resource
    Effects of GaAs and Ga2O3 on magnetometric behavior of iron oxide particles in rabbit lungs (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Applied Organometallic Chemistry 8 (1994), S. 207-213 
    Details
    ISSN: 0268-2605
    Keywords: Magnetometry ; gallium arsenide ; gallium oxide ; clearance ; relaxtion ; microelectronics ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Intratracheal instillation of a GaAs suspension has been histopathologically shown to induce a diffuse pulmonary response. In the present study, magnetometry was used to evaluate the effects of intratracheally instilled GaAs and Ga2O3 on the behavior of externally magnetized iron oxide (Fe3O4) particles instilled in rabbit lung. Magnetometric evaluation of the effects of GaAs in rabbits dosed with 30 mg or 300 mg per animal showed a significantly decreased relaxation of iron oxide particles at 1, 3, 7, 14, 21 and 28 days following instillation compared with the controls. On the other hand, in the rabbits exposed to Ga2O3, significantly reduced decay constants were observed only on the first and third days following instillation.Relaxation indicates a rapid decrease of remanent magnetic field following magnetization of the lungs due to random rotation of phagocytosed iron oxide particles in macrophages.Clearance of the iron oxide particles was measured by serial determinations of the remanent magnetic field at the end of magnetization estimated from relaxation curves. Clearance was significantly impaired at 14, 21 and 28 days after instillation in rabbits exposed to both doses of GaAs. Slightly delayed clearance was also observed in rabbits exposed to Ga2O3.Histological examination of lungs instilled with GaAs indicated active phagocytosis of GaAs and iron oxide particles by pulmonary macrophages, as well as pneumonocytes hyperplasia with marked thickening of the alveolar walls. Minimal histological changes with retention of iron oxide particles were found in the lungs exposed to Ga2O3.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aoc.590080309
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  • 6
    Electronic Resource
    Electronic Resource
    Diazoalkankomplexe mit Nickel(0) und Palladium(0) und ihre Bedeutung für Carbenoidreaktionen (1975)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1975 (1975), S. 626-635 
    Details
    ISSN: 0075-4617
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Diazoalkane Complexes of Nickel(0) and Palladium(0) and Their Relevance to Carbenoid ReactionsA series of diazoalkane complexes with the composition ML2(diazoalkane) [M = Ni, Pd; L = tBuNC, PPh3; diazoalkane = 9-diazofluorene or diphenyldiazomethane] have been prepared and characterized, and their thermolysis and displacement reactions investigated. The nickel complexes catalyse a carbenoid reaction which leads to ketenimine formation. A carbene complex having the formula Pd(PPh3)2(C13H8) was obtained by low temperature thermolysis of Pd(PPh3)2(9-diazofluorene).
    Notes: Eine Reihe von Diazoalkankomplexen mit der Zusammensetzung ML2(Diazoalkan) [M = Ni, Pd; L = tBuNC, PPh3; Diazoalkan = 9-Diazofluoren oder Diphenyldiazomethan] wurde dargestellt und charakterisiert; ihre Thermolyse- sowie Verdrängungsreaktionen wurden untersucht. Die Nickelkomplexe katalysieren eine Carbenoidreaktion, die zur Keteniminbildung führt. Tieftemperaturthermolyse von Pd(PPh3)2(9-Diazofluoren) lieferte einen Carbenkomplex der Zusammensetzung Pd(PPh3)2(C13H8).
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.197519750405
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  • 7
    Electronic Resource
    Electronic Resource
    Role of 2-carboxyl substituent in the tautomerization between two equivalent enol forms of 3-hydroxyphenalenone (1990)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 3 (1990), S. 485-488 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The interconversion between two equivalent enol forms of 3-hydroxyphenalenone took place predominantly through a diketo form with a free energy of activation of ca 14 kcal mol-1 in DMSO solution determined by 125·8 MHz13C NMR measurement. On the other hand, the corresponding interconversion in 2-carboxy-3-hydroxyphenalenone was not frozen on the time scale of 13C NMR spectroscopy down to -60°C. This acceleration in the interconversion rate of the latter may be interpreted by a double proton switching between the hydrogen-bonded 2-carboxyl and 3-hydroxyenone moieties.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610030712
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  • 8
    Electronic Resource
    Electronic Resource
    MO study of the possibility of a concerted mechanism in the pinacol rearrangement (1990)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 3 (1990), S. 737-745 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The ab initio SCF-MO method was employed to examine the possibility of a reaction pathway without a carbocation intermediate in the pinacol rearrangement. The molecular geometries of the transition states were obtained for the 1,2-hydride shift together with H2O elimination, starting from the various methyl-substituted protonated 1,2-diols. It was found that the activation energies depend strongly on the substitutents. A comparison of the relative energies between β-hydroxycarbonium ions and the transition states of the concerted mechanism suggests that the stepwise mechanism is less favourable than the concerted path in each case.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610031107
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  • 9
    Electronic Resource
    Electronic Resource
    Interaction Between Benzene and Naphthalenophane: In the Gas Phase and the Crystalline Lattice (1997)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1997 (1997), S. 1769-1776 
    Details
    ISSN: 0947-3440
    Keywords: Naphthalenophane ; Clathrate ; Ab initio calculation ; Semiempirical calculation ; Edge-to-face interaction ; Phanes ; Arenes ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The interaction between naphthalenophane 1 and another aromatic compound in the gas phase was investigated by molecular orbital calculations, mainly focusing on the arrangement of both aromatic compounds and the effect of the substituents in the benzene ring. The X-ray crystallographic analysis of some clathrates of 1 with an aromatic solvent was also carried out in order to clarify the relationship between the gas and condensed phases. The most stable arrangement calculated for a complex of 1 and benzene or substituted benzene in the gas phase was found to be the arrangement in which the edges of the two naphthalene rings of 1 are directed to the face of the benzene ring. Such an arrangement was also observed in the clathrate crystals, according to the X-ray crystallographic analysis. This result suggests that the stable arrangement in the gas phase is probably maintained in solution, leading to the same arrangement in the crystals. The order of stabilization of the clathrates with some substituted benzenes is in agreement with that of the electron-donating ability of the functional group present in the benzene. A slight difference in the stabilization was observed between the complex with toluene and that with chlorobenzene, and such a difference is considered to affect the inclusion behavior of 1.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.199719970821
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  • 10
    Electronic Resource
    Electronic Resource
    Photocyclisierungen von 1, 1'-Polymethylen-di-2-pyridonen. 46. Mitteilung über Photoreaktionen45. Mitt. siehe [1]. (1976)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 59 (1976), S. 2841-2854 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Photocyclization of 1, 1′-Polymethylene-di-2-pyridones.Benzophenone sensitized irradiation of the four dipyridones 1-4 gave the internal photocyclization products 6 (64%, Scheme 4), 7 (60%, Scheme 5), 8 (Scheme 6), and 11 (26%, Scheme 7), respectively. The decamethylene compound 5 yielded only polymeric material.The primary [2+2] photoproduct 8 from dipyridone 3 (Scheme 6) is relatively unstable. Further irradiation or heating to 65° induced a Cope rearrangement to give compound 9 which, on heating to 137°, was converted into the isomeric compound 10. This product, as well as the other photoproducts mentioned, are rearranged back to their respective starting materials upon direct irradiation with 254 nm light or by heating to higher temperatures. The various possibilities for cycloadditions of pyridones are discussed as well as the possible factors which are responsible for the highly regioselective photoreactions of the dipyridones 1-4.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19760590822
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