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  • 1975-1979  (57)
  • 1970-1974  (24)
  • 1960-1964  (19)
  • 1910-1914
  • 1890-1899
  • Heterocycles
  • Phosphorus
  • Synthetic methods
  • 1
    ISSN: 1434-4475
    Keywords: Enamines, synthesis ; Heterocycles
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Condensation of alkyl γ-haloacetoacetates (or γ-chloroacetoacetanilide) with triethoxymethane and primary (hetero)aromatic amines gives in a one step synthesis under mild conditions new β,β-diacyl-enamines (2 a-m, 3 a-d). In contrast, the N-alkylsubstituted derivatives could be synthesized only in a two step procedurevia the enolethers6 a, b. According to their ir-specra, most of the aminomethylene-γ-haloacetoacetic acid derivatives are stereochemically fixed either in theE- orZ-form. The pmr-spectra, however, show that they exist as mixtures of at least two isomers in solution. With KOH or sodium acetate, a ring closure to 3-hydroxy-pyrroles (8, 9) could be achieved whereas with pyridine only quarternary pyridinium salts (11) are formed. Acidic (orLewis acidic) condensing agents leave the chloroacetyl group unaffected and give either free carboxylic acids (2 p-r) pyrido-[1,2-a]pyrimidones (12) or 4-quinolones (13), depending on the type of the molecule and the reaction temperatures employed.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Calcified tissue international 27 (1979), S. 19-26 
    ISSN: 1432-0827
    Keywords: Bone diseases ; Familial hypophosphatemia ; Magnesium ; Mice ; Phosphorus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary A new genetic mutant in mice,Hyp, has been proposed as a model for the human disease X-linked hypophosphatemia (the most common form of vitamin D-resistant rickets). The gene is X-linked, dominant, and produces reduced renal tubular reabsorption of phosphate, hypophosphatemia, and dwarfism. Our goal was to evaluate the skeletal changes histologically and to measure chemically the prominant blood and bone minerals to judge the suitability of this mutant as a model for the human disease. Thirteen-week-old hemizygousHyp male mice were compared with their normal littermate controls. TheHyp mice were hypocalcemic, hypophosphatemic, hypermagnesemic, and had elevated plasma alkaline phosphatase. The femur ash weighed less than half the normal ash weight but had a normal Ca:P ratio. The ash composition was high in %Na and K but low in %Mg. The mandibular incisor ash was also low in %Mg. Histologically the femur showed wide osteoid borders and wide epiphyseal plate. Microradiography revealed reduced bone density and enlarged osteocyte lacunae. Skeletal muscle samples, although smaller in theHyp mice, showed no striking alternations in inorganic or total phosphate content, dry weight (as % wet weight), or extracellular fluid space. TheHyp gene in mice seems to produce a condition similar to that of X-linked hypophosphatemia in humans.
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Chromatographia 12 (1979), S. 212-214 
    ISSN: 1612-1112
    Keywords: Phosphorus ; Chromatography, gas-liquid ; Alloys, copper
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A simple, sensitive, accurate and rapid gas chromatographic method for the quantitative determination of phosphorus in copper-phosphorus alloys is described. The method is based on the chlorination of the sample with carbon tetrachloride in a sealed glass capsule at 550°C. The volatile products are introduced into the gas chromatograph after crushing the capsule in a special device. The method is very quick (ca. 20 min), involves simple manipulations and the error is about ±0.5%.
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Plant and soil 51 (1979), S. 247-256 
    ISSN: 1573-5036
    Keywords: Nutrient distribution ; Phosphorus ; Tropical legumes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Changes in absolute contents of nutrient elements of old leaves of two tropical pasture legumes were studied during vegetative growth in order to determine the extent of nutrient reutilization. Over a wide range of P supply, the P contents of old leaves ofDesmodium intortum cv. Greenleaf generally increased slightly with time whereas inMacroptilium atropurpureum cv. Siratro they decreased. In both species, relatively less K than P was retained in old leaves, especially in plants grown at high P supply. In desmodium, contents of N, S, Ca, Mg, B, Zn and Mn in old leaves generally increased with plant age. In Siratro, S content of old leaves decreased, but to a lesser extent than P content, and contents of N, Ca, Mg, B, Zn and Mn either changed little or increased with plant age. The lower net loss of elements from old leaves of desmodium than Siratro was associated with a greater increase over time in dry weight of old desmodium leaves. The losses of elements other than K from old leaves of Siratro and desmodium with time were relatively smaller than those reported for other species. This suggests that these legumes survive restricted supply of such elements from the roots by reducing their growth rather than by reutilizing nutrients in old leaves. By contrast, these plants can continue to grow when K supply from the roots slows or ceases by utilizing K in old tissues for growth of young tissues.
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Plant and soil 51 (1979), S. 485-490 
    ISSN: 1573-5036
    Keywords: Crude protein ; Fodder ; Nitrogen ; N/S ratio ; Phosphorus ; Protein ; Raya ; Selenium ; S-amino acids
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The effects of Se and P on the dry matter yield and chemical composition of Raya (Brassica juncea Cos. var. R.L. 18) were studied in the green-house. The dry matter yield in P treated and untreated pots increased with Se application upto 2.5 ppm. With further increase in Se dose upto 10 ppm, dry matter yield decreased. The increase in P dose from 0 to 50 ppm increased dry matter yield in all Se treated and untreated pots but 100 ppm P rather showed decrease in dry matter yield as compared to 50 ppm P. The Se concentration increased by about 100 fold with the application of 10 ppm Se over 0 ppm Se where P was not added whereas increase was 258 and 336 times when 50 ppm and 100 ppm P was added, respectively. Inorganic, organic and total P increased with increasing Se and P. The increase in inorganic P was more than organic and total P. S and N concentration decreased with increasing Se application and increased with P application. Crude protein showed the same behaviour as N. The total sulphur-containing amino acids (which ranged from 39 to 49% of crude protein) and individual sulphur-containing amino acids like methionine (16.9 tot 20%) cysteine (9.8 to 13%) and cystine (12.3 to 15.9%) decreased with the increasing selenium but increased with increasing phosphorus. N/S ratio in the plant showed significant negative correlation with total sulphur-containing amino acids (r=−0.940**), methionine (r=−0.951**), cysteine (r=−0.929**) and cystine (r=−0.920*) whereas total sulphur in the plant showed positive significant correlation with methionine (r=0.805**), cysteine (r=0.924**) and cystine (r=0.821**).
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  • 6
    ISSN: 1573-5117
    Keywords: Phosphorus ; herbicide ; diquat ; nutrient cycling ; sediment
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Phosphorus (P) concentrations in water and sediment of a highly eutrophic lake were monitored before and after application of diquat to control the macrophyte Potamogeton crispus. Only a relatively small and short-term increase in P concentration in water occurred shortly after plant die-off resulting from herbicide application. Phosphorus concentrations in shallow water sediments decreased during the summer, and those in deep water sediments increased. Although a large increase in P concentration in the water occurred in late summer, it was not attributed to diquat. No major secondary effects of herbicide application were found during this study.
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Plant and soil 51 (1979), S. 331-340 
    ISSN: 1573-5036
    Keywords: Deficiency ; Distribution ; Fruit ; Glasshouse ; Laminae ; Leaves ; Nitrogen ; Peat ; Petioles ; Phosphorus ; Plant ; Superphosphate ; Symptoms ; Tomato ; Uptake
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The uptake and distribution of phosphorus was examined in tomato plants, cv. Kirdford Cross, grown in peat to which phosphate was added (P2) or omitted (P1). The plants received a liquid feed containing either a high (N2) or low (N1) concentration of ammonium nitrate. Initially, all plants were grown in peat containing an intermediate level of phosphate. There was a rapid net export of P from the leaves of plants transferred to the P1 medium resulting in deficiency symptoms before the fruit on the first truss had ripened. Most of the P absorbed by 11-week-old plants in the N1P2 and N2P2 treatments was located in the developing fruit, in the laminae of the mature leaves and in the lower parts of the stem. In the P1 treatments, the lowest fruit truss was the dominant sink for the limited supply of P, but there was also a significant concentration of P in the shoot apex and in the laminae. Increasing the supply of N to plants in the P2 treatment promoted the transport of P to the shoot and to the fruit trusses and also increased the total P uptake. However, plants in the N2 treatment required a significantly higher level of tissue P to prevent the symptoms of P deficiency occurring in the laminae. Generally, symptoms occurred in laminae of mature leaves containing less than 0.13 per cent P. Increases in concentration of tissue P in response to raising the level of applied P were greatest in the petioles of the mature leaves, and it is suggested that these petioles are the most suitable tissues for the assessment of the P status of tomato plants.
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Plant and soil 51 (1979), S. 341-353 
    ISSN: 1573-5036
    Keywords: Fruit development ; Glasshouse ; Growth ; Nitrogen ; Peat ; Phosphorus ; Protein ; Sand ; Tomato
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The effect of P nutrition on the growth of tomato plants in peat was examined. Initially, plants received an adequate supply of P and then received either nil, 0.78 or 2.34 kg superphosphate per m3 in combination with either 50 μg N/ml (N1) or 300 μg N/ml (N2) as ammonium nitrate in a liquid feed. Vegetative growth was restricted in the lower P treatmentsi.e. inhibited shoot growth, reduced duration of leaf expansion phase, thinner stems and reduced vegetative dry wt. Plants receiving N2 showed a greater restriction in growth compared with N1 plants when the P supply was limiting. P deficiency disrupted protein metabolism in the leaves, in that soluble leaf protein was reduced and trichloroacetic acid-soluble N accumulated. Flower development was accelerated by low P applications but the final numbers of flowers and the fruit-setting efficiency were reduced. Lowering the N supply reduced the fruit yield by 36 per cent while an intermediate P level reduced yields by about 15 per cent. Maximum fruit yields and good vegetative growth occurred when plants contained 0.4 per cent P or above in the mature leaves, and this value was achieved by adding the highest level (2.34 kg/m3) of superphosphate to the peat.
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Plant and soil 51 (1979), S. 551-561 
    ISSN: 1573-5036
    Keywords: Autoradiography ; Culture solution ; Fe deficiency ; Millet ; P/Fe interaction ; Phosphorus ; Sorghum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Seedlings of millet (Pennisetum americanum (L) K. Schum var. Tift 23 DA × Tift 18 DB) and guineacorn (Sorghum bicolor (L) Moench var. RS' 702) were employed in growth chamber studies to evaluate the effects of various phosphorus (P) levels on their growth and nutrient composition. The growth medium was Hoagland solution containing 0.0, 0.1, 1.0 and 2.5 mM P and 2.2 mM ferrous sulphate-tartate solution. At the end of twenty-four days, two plants from each treatment were supplied with 0.31 μci/ml of radioactive iron (55Fe) (with the same P levels used to grow them) and then allowed to absorb the55Fe for 3 hours after which they were harvested, separated into roots and shoots. The two components were wet-ashed separately, and assayed for55Fe. The rest of the plants in Hoagland solution were also harvested, separately into roots and shoots. The components parts were also wet-ashed separately and assayed for iron (Fe), manganese (Mn), zinc (Zn), copper (Cu) and phosphorous (P). High P concentration in the growth medium inhibited55Fe absorption and translocation in both millet and sorghum but millet was more tolerant of P-induced Fe deficiency than sorghum. Millet and sorghum grew best at 1.0 and 0.1 mM P, respectively. Fe concentrations in plant declined as P levels increased; while Mn increased in both millet and sorghum with increasing P levels. Millet, however, maintained higher concentrations of Fe and Mn. The distribution patter of55Fe, regardless of P levels could be summarized as follows: Roots〉Vascular tissue〉leaf-sheaths〉leaf blade. Less55Fe was absorbed and translocated to shoots at 2.5 mM P, in millet and sorghum.
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  • 10
    ISSN: 1573-5036
    Keywords: Gaeumannomyces ; Phialophora ; Phosphorus ; Potassium ; Water use ; Wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The water consumption and levels of phosphorus, potassium, and total minerals were measured for wheat seedlings colonized byGaeumannomyces graminis var.tritici, Phialophora radicicola var.radicicola, orPhialophora radicicola var.graminicola. Infection byG. graminis resulted in a considerable reduction in water consumption, and reduced level of phosphorus when the supply of phosphorus to the seedlings was plentiful. Colonization byP. radicicola var.radicicola increased levels of phosphorus and potassium, but these increases varied according to the isolate of the fungus and the supply of phosphorus and potassium available to the seedlings. Colonization byP. radicicola var.graminicola resulted in reduced water consumption by the seedlings. The results are discussed in relation to stelar cell wall thickening in wheat roots colonized byP. radicicola, and the effects on nutrient uptake of mycorrhizal root systems.
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  • 11
    ISSN: 1573-5036
    Keywords: Foliar fertilization ; Growth ; Leaf area ; Mineral composition ; Peanut ; Phosphorus ; Sand culture ; Stomatal frequency ; Yield
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Peanut (Arachis hypogaea L., Var. TMV-2) plants were raised in sand cultures under natural photoperiod. Salt treatment (0.4% NaCl on dry weight basis) was given 10 days after sowing. Nutrient solution was supplied 15 days after sowing to control and salinized plants. Phosphate (0.1% NaH2PO4 with 0.01% Tween-80) was sprayed to the plants to the drip point once daily from 20th to 25th day and from 30th to 35th day. The plants were harvested at 30th and 40th day for analysis. The plants grown under saline conditions showed a market reduction in growth. When phosphorus was supplied to saline plants by foliar application, there was an increase in dry weight, leaf area, stomatal frequency, and yield and the increase was more marked when the plants received phosphate for two periods. Phosphorus content decreased due to salinity which was restored by foliar spray of phosphate. With salinity, sodium accumulated while potassium and calcium were lowered. Phosphate spray decreased sodium and increased potassium and calcium in general.
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  • 12
    Electronic Resource
    Electronic Resource
    Springer
    Plant and soil 52 (1979), S. 139-149 
    ISSN: 1573-5036
    Keywords: Algal growth ; Iron ; Manganese ; Phosphorus ; Rice soils
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Laboratory experiments were conducted to study the effect of algal growth on the change of (I) pH, (II) available phosphorus and (III) solubility of iron and manganese content in five waterlogged alluvial rice soils of West Bengal, India. The results showed that the algal growth initially caused an increase in the soil pH, which later declined to the original value in some of the soils. The available phosphorus content decreased upto 90 days of their growth and began to increase towards the later period of incubation. The drastic fall of water soluble plus exchaneable manganese content of the soils due to algal growth was accompanied by similar increase in reducible manganese content. No appreciable change in water soluble plus exchangeable ferrous iron content was encountered but theN-NH4OAC(pH 3) extractable iron due to algal growth progressively decreased with the progress of the incubation period.
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  • 13
    ISSN: 1573-5036
    Keywords: Alluvial soil ; Alternate waterlogged and saturated ; Copper ; Immobilization ; Interaction ; Iron ; Manganese ; Organic matter ; Phosphorus ; Reduction ; Rice ; Saturated ; Waterlogged ; Zinc
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary A laboratory incubation experiment was conducted to study the influence of three moisture regimes,viz (i) waterlogged (W1), (ii) alternate waterlogged and saturated (W2) and (iii) continuous saturated (W3) and two levels of organic matter application,viz (i) 0 (T1) and (ii) 0.5% of the soil (T2) in their all possible combinations on the extractable (N NH4OAC, pH 7.0) zinc and copper in three lowland alluvial rice-growing soils of West Bengal (India). The results showed that the extractable zinc and copper content in soils recorded marked decrease on incubation under all the moisture regimes, but the same was most prominent under the continuous saturated moisture regime (W3), followed by waterlogged (W1) and alternate waterlogged and saturated (W2) moisture regimes. Application of organic matter brought about further decrease in the content of these elements. Organic matter application combined with saturated moisture regime brought about the greatest decrease both in zinc and copper content. The microbiological immobilisation and the antagonistic effect of increased concentration of extractable iron, manganese and phosphorus have been suggested as the possible reasons for the observed decrease of the content of extractable zinc and copper.
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  • 14
    ISSN: 1573-5117
    Keywords: Fertilizer ; Nutrients ; Soluble Phosphate ; Equilibrium Phosphate Concentration ; Phosphorus ; Pond ; Sediment ; Erosion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We chose two surface soils with contrasting textures as model sediments for a model pond study. One soil, a calcareous clay, had a relatively high natural phosphate content and a large phosphate adsorption capacity. The second soil, a non calcareous loam, had a relatively low natural phosphate content and a small phosphate adsorption capacity. Chemical characteristics of both soils were roughly proportional to mineral surface area. Pasture sites of each soil were tilled to a depth of 15 cm and two plots at each site were fertilized by hand with triple superphosphate. A third plot at each site was left unfertilized. After fertilization the plots were mechanically mixed and left fallow for 2 to 3 months. Then the plots were resampled and equilibration phosphate concentrations were determined again. Results showed significant phosphate fixation by the clay soil but no fixation by the loam soil.
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  • 15
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 18 (1979), S. 515-529 
    ISSN: 0570-0833
    Keywords: Pyrolysis ; Sulfones ; Synthetic methods ; Ring contraction ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Cyclic sulfoness containing structural elements such as aromtic rings, heteroatoms. functional groups, and further SO2-groups as ring members decompose on heating with cleavage of SO2 and formation of a new C—C bond. In the last decade this “sulfone pyrolysis” has been expanded into a generally applicable method even allowing the synthesis of sterically strianed medium-membered and multi-membered cyclic and polycyclic systems containing aromatic ring. By the pyrolysis of sulfones which are only unilateally activated by benzyl moieties, aromatic systms can be bridged by —(CH2)n chains of any desired length. In addition, —(CH2)— chains can be split off together with two SO2 molecules, with recombination of the remaining centers, resulting in ring contraction by four to n atoms. However, sulfone pyrolysis is of importance not only as a ring-contraction method but as a crucial final step in the synthesis of multi-membered hydrocarbon cycles, e.g. of the phane type.
    Additional Material: 7 Ill.
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  • 16
    ISSN: 0570-0833
    Keywords: Donor-acceptor systems ; Substituent effects ; Free radicals ; Radicophiles ; Synthetic methods ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The 100 yers old Wurster's salts have long been recognized as compounds with redical cations. Their unusual stabilization derives partly form capto-dative (cd) substitution. This principle is now discussed as one factor of radical stabilization and it is applied to simple methine derivatives. cd-Substitution has synthetically useful applications: cd-substituents on a carbon atom allow its selective dehydrodimerization. Olefines with geminal and thus cross-conjugated cd-substituents are “radicophilic” and permit twofold carbon radical addition. cd-Substituted olefines are useful antioxidants, polymerization inhibitors and are promising agents in the control of biological radical reactions. Generally, many reactions of cd-substituted molecules appear to involve radicals.
    Additional Material: 6 Ill.
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  • 17
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 18 (1979), S. 421-429 
    ISSN: 0570-0833
    Keywords: Triphase catalysis ; Catalysis ; Synthetic methods ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Triphase catalysis (TC) has recently been introduced as a unique form of heterogeneous catalysis in which the catalyst and each of a pair of reactants are located in separate phases. Based on this concept, new synthetic methods have been developed for aqueous phase-organic phase reactions using a solid phase catalyst. Although it is only at an early stage of development, TC shows considerable potential for practical use. Our mechanistic understanding of these highly complex catalytic systems is at present very limited and detailed examination will be required before their relationship to phase-transfer, micellar, and interfacial catalysis becomes clear.
    Additional Material: 2 Ill.
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  • 18
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    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 18 (1979), S. 1-19 
    ISSN: 0570-0833
    Keywords: Areno-analogy ; Heterocyclopolyaromatic compounds ; Heterocycles ; Heteroaromatic compounds ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Organometallic linkage of heteroaromatic compounds provided a means of synthesizing complicated combinations of heteroaromatic compounds; not only nucleophilic aromatic substitution, but also “Ar—Cu/Ar—Hal linkage”, “organometallic oxidative linkage”, and “metal amide linkage” have been employed. The heterocyclopolyaromatic compounds are made of one, two, or three kinds of heteroaromatic species as ring members. These syntheses illustrate the construction of heterocycles from large, performed structural units. Competition experiments showed that the reactivity typical of the individual species is enhanced in open-chain combinations (ArNu)n and (ArE)n (ArNu, ArE: nucleo- and electrophilic heteroaromatic systems, respectively); the opposite situation is mostly encountered in the case of ArNu—AE combinations. - Cycloocta[1,2-b:4,3-b′5,6-b″:8,7-b‴]tetrathiophene, the only heterocyclopolyaromatic system yet to have been studied in detail, proved surprisingly inclined to undergo monosubstitution reactions.
    Additional Material: 3 Ill.
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  • 19
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    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 18 (1979), S. 837-846 
    ISSN: 0570-0833
    Keywords: C-C coupling ; Synthetic methods ; Catalysis ; Silanes ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The reagent hydrosilane/carbon monoxide opens up new possibilities for organic synthesis. Four cases will be discussed: 1. The reaction of olefins with hydrosilane (trialkylsilane) and carbon monoxide in the presence of Co, Ru, and Rh complexes leads to enol silyl ethers having one more carbon atom that the olefins. 2. Cyclic ethers underto carbonylative ring opening to ω-siloxyaldehydes when reacted with hydrosilane and carbon monoxide in the presence of Co2(CO)8 as catalysts 3. Aldehydes are catalytically converted into the next higher α-siloxyaldehydes or 1,2-bis(siloxy)alkenes depending on the reaction conditions used. 4. The reaction of alkyl acetates proceeds in various ways depending on the nature of the alkyl group; enol silyl ethers or alkenes are optained.-Mechanisms of these Co2(CO)8 catalyzed reactions using hydrosilane and carbon monoxide are discussed in which HCo(CO)n or R3SiCo(CO)nL function as catalytically active agents. With these species there are four types of catalytic cycles.-The synthetic possibilities of these catalytic reactions have still not been fully explored.
    Additional Material: 2 Tab.
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  • 20
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    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 18 (1979), S. 900-917 
    ISSN: 0570-0833
    Keywords: Arylnitrene chemistry ; Synthetic methods ; Nitrenes ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Aryl- and heteroaryl-nitrenes can take part in intra-and intermolecular reactions in both of their possible electronic states (triplet and singlet). In this review we have endeavored to high-light recent synthetic uses of these reactive intermediates as well as draw attention to avenues open to further exploration in this field. Singlet arylnitrenes will interact with suitable ortho-positioned substituents to give a variety of fused azoles, some in excellent yield. In suitable solvents and in presence of amines and alcohols, phenylnitrenes undergo ring expansion to azepines which can also occur in nitrenes of certain fused bicyclic aromatics (naphthalene, quinoline, isoquinoline, benzo[b]thiophene). The latter nitrenes may also give rise to o-diamines which are useful starters for further heterocyclic synthesis. Triplet arylnitrenes (usually regarded as having only a nuisance effect in synthetic work) may also be utilized in practicable heterocyclic syntheses within a suitable molecular framework. Decomposition of aryl azides in a mixture of an organic and polyphosphoric acid leads to fused oxazoles. The mechanism is discussed for all the reactions considered.
    Additional Material: 8 Tab.
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  • 21
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    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 18 (1979), S. 707-721 
    ISSN: 0570-0833
    Keywords: Onium compounds ; Aza-arenes ; Synthetic methods ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Effective syntheses employing 2-halogenated pyridinium, benzoxazolium, benzothiazolium, and pyridinium salts have been accomplished in the absence of strong acids and bases. Activation of carboxylic acids or alcohols with these onium salts leads to 2-acyloxy and 2-alkoxy intermediates which can be transformed into esters, amides, thiol esters, (macrocyclic) lactones, acid fluorides, olefins, allenes, carbodiimides isocyanates, isothiocyanates, nitriles, and isocyanates. The possibility of performing stereospecific syntheses (involving configurational inversion) with onium salts deserves attention.
    Additional Material: 20 Tab.
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  • 22
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    Hydrobiologia 57 (1978), S. 209-215 
    ISSN: 1573-5117
    Keywords: Phosphorus ; growth rate ; phytoplankton
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Laboratory experiments with natural phytoplankton assemblages from three lakes (two mesotrophic and one oligotrophic) showed that added PO4 predictably affected growth rate (µ, determined as P : B) while NO3 had little effect even when the N P ratio approached one. The response to PO4 followed the typical Monod-type function. The lack of effect of NO3 on µ at such low N : P ratios is in striking contrast to the added effect of NO3 Plus PO4 on maximum biomass produced versus only PO4 alone.
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  • 23
    ISSN: 1573-5117
    Keywords: Phytoplankton ; Eutrophication ; Ordination analysis ; Diatoms ; Nutrient enrichment ; Phosphorus ; Laurentian Great Lakes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A natural phytoplankton assemblage from Grand Traverse Bay, Lake Michigan, was treated with factorial enrichments of nitrate and phosphorus, with maintained nutrient concentrations ranging from 5 to 60 µg total soluble phosphorus liter−1 and 0.225 to 1.12 mg nitrate-nitrogen liter−1.One container was spiked with added vitamins, a chelator, and trace metals. The assemblage response was monitored at the species level. Significant differences in growth rates as a function of nutrient enrichment were detected at both the division and the species levels. Growth rates associated with the various levels of enrichment are reported for several diatom taxa. Many of the diatom taxa exhibited highly significant (P 〈 0.01) increases in growth rate after phosphorus enrichment, with the largest effects occurring between 5 and 15 µg total soluble phosphorus liter−1. Significant (P 〈 0.05) N effects were also observed, and the nature of these effects was found to be taxon-specific. Taxa also showed significant changes in percent composition, due both to time and to nutrient enrichment, indicating a substantial heterogeneity in response at the species level. Experimentally induced population changes were qualitatively similar to those observed in regions of the Great Lakes which have undergone anthropogenic eutrophication.
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  • 24
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    Electronic Resource
    Springer
    Hydrobiologia 59 (1978), S. 151-154 
    ISSN: 1573-5117
    Keywords: Remineralization ; Phosphorus ; SRP ; Freshwater Zooplankton
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract During a six-month study at Lake George, N.Y., zooplankton contributed an average of 19.4% of the phosphate required for algal photosynthesis. Values ranged from 44.1% prior to the unimodal phytoplankton pulse to 4.6% during the phytoplankton bloom. Copepods accounted for a large percentage (21–68%) of the SRP recycled during the growing season examined, whereas, the cladocera provided only a small percentage of remineralization (6.9%).
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  • 25
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    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 17 (1978), S. 476-486 
    ISSN: 0570-0833
    Keywords: Intramolecular reactions ; Ene reaction ; Synthetic methods ; Cyclization ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Thermal cyclizations of appropriate dienes, enynes and related unsaturated systems, some of them carried out on an industrial scale, demonstrate increasingly the preparative power of the intramolecular ene reaction. A variety of substituted, fused and bridged ring systems, including natural products, are thus easily accessible in a regio- and stereo-selective manner. Numerous examples are discussed systematically illustrating the possibilities, limitations, and common features of this cyclization reaction and its reverse ring-opening process.
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  • 26
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    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 17 (1978), S. 27-37 
    ISSN: 0570-0833
    Keywords: Organomercury compounds ; Synthetic methods ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Organomercurials have been known since 1850 and many synthetic routes to these compounds presently exist. The ability of these compounds to accommodate a wide variety of functional groups and to tolerate quite diverse reaction conditions makes them attractive as synthetic intermediates. While the solvomercuration-demercuration and divalent carbon transfer reactions remain the most widely used of the organomercurial reactions, a number of new synthetic procedures employing organomercurials have been developed in recent years. Many of these involve transmetallation reactions with palladium salts.
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  • 27
    ISSN: 0570-0833
    Keywords: Oxygenation ; Alkanes ; Synthetic methods ; Superacidic systems ; Catalysis ; Magic acid ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Owing to the ready availability of the starting materials, the functionalization of saturated hydrocarbons for preparing chemical intermediates and products represents an attractive goal. The possibility of converting alkane in a controlled way into alcohols, ketones etc., i.e. to oxyfunctionalize them, is particularly challenging. After a short account of previous methods used for the oxidation of alkanes, particular emphasis will be given to recently developed reactions of alkanes with oxygenating agents in superacidic media.
    Additional Material: 16 Tab.
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  • 28
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    Angewandte Chemie International Edition in English 17 (1978), S. 169-175 
    ISSN: 0570-0833
    Keywords: Organoaluminum compounds ; Selectivity ; Synthetic methods ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: With the aid of selected examples an overview is given of the development trends in highly discriminative reactions using organoaluminum compounds. (1) Isomerization of substituted oxiranes into allyl alcohols has been effected both stereo- and regioselectively by means of a new organoaluminum reagent, diethylaluminum 2,2,6,6-tetramethylpiperidide (DATMP); this reaction which provides a new route for the regiospecific transformation of allyl alcohols into 1,3-dienes. (2) A novel nonenzymic heterolysis of allylic phosphates of terpenoids has been effected by organoaluminum compounds and has enabled development of a new method for the selective synthesis of cyclic terpenes. (3) The reductive condensation of α-haloketones with carbonyl compounds in the presence of diethylaluminum chloride and zinc affords β-hydroxy-carbonyl derivatives in good yields with exclusion of undesired self-condensations products.
    Additional Material: 3 Ill.
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  • 29
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    Angewandte Chemie International Edition in English 17 (1978), S. 487-496 
    ISSN: 0570-0833
    Keywords: Alumina surfaces ; Synthetic methods ; Surface chemistry ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Recent examples are given to emphasize that alumina can cause many different and often unexpected chemical reactions of adsorbed organic molecules. Recent developments are summarized to publicize that reagent-doped alumina can be used deliberately to achieve some very mild and highly selective organic transformations. The scope and limitations of organic reactions at alumina surfaces are discussed, and the advantages of these heterogeneous reactions over the corresponding homogeneous ones are pointed out. The role of the alumina and future problems are discussed briefly.
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  • 30
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    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 17 (1978), S. 505-515 
    ISSN: 0570-0833
    Keywords: Pyridines ; Alkynes ; Nitriles ; Synthetic methods ; Cobalt catalysts ; Catalysis ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Soluble organocobalt catalysts permit selective formation of substituted pyridines under mild conditions in a single step: mono-, di-, and trisubstituted pyridines can be obtained at will in high conversions and high yields from nitriles and alkynes. Polynuclear derivatives such as bipyridines can also be prepared by this method.
    Additional Material: 1 Ill.
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  • 31
    ISSN: 0570-0833
    Keywords: 4-Dialkylaminopyridines ; Amino pyridines ; Acylation ; Catalysis ; Synthetic methods ; Pyridines ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The synthesis of 4-dialkylaminopyridines can be accomplished in two steps starting from pyridine. Compared to pyridine, these derivatives are approximately 104 times more active when used as acylation catalysts. Dialkylaminopyridines are being used with ever-increasing frequency for acylation reactions which proceed either incompletely or not at all in pyridine. This article reviews the various possible applications of 4-dialkylaminopyridines in terpene, steroid, carbohydrate and nucleoside chemistry as well as in the transformation of amino acids into α-acyl aminoketones and polymerization of isocyanates. In addition, N-substituted 4-dialkylaminopyridinium salts can be used for the transfer of sensitive groups to nucleophiles in aqueous medium. The exceptional catalytic effect of these derivatives, even in non-polar solvents, is due, in part, to the formation of high concentrations of N-acylpyridinium salts which are present in solution as loosely-bound, highly reactive ion pairs.
    Additional Material: 2 Ill.
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  • 32
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    Calcified tissue international 23 (1977), S. 121-124 
    ISSN: 1432-0827
    Keywords: Vitamin D ; Metabolic acidosis ; Phosphorus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary The metabolism of vitamin D3 was studied in 3-week-old, vitamin D deficient chicks, fed since hatching with a diet containing 3% ammonium chloride, 1% calcium, and 0.7% phosphorus. When kidney homogenates were incubated in vitro with [3H]25-(OH)D3, the production of 1,25-(OH)2D3 was reduced by 40% in acidotic birds. During in vivo experiments, after injection of [3H]D3 (1220 pM/bird), the level of 1,25-(OH)2D3 was also reduced in blood plasma, intestine, and tibiae in acidotic chicks as compared with the controls. As a large increase in plasma phosphate was found during acidosis, these results are discussed in relation to the possible role of phosphorus in the control of 1,25-(OH)2D3 synthesis.
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  • 33
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    Calcified tissue international 22 (1977), S. 9-17 
    ISSN: 1432-0827
    Keywords: Bone ; Fluoride ; Calcium ; Phosphorus ; Mechanical Strength
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Abstract Four groups of weanling rats were fed for 2 weeks on a diet sufficient or insufficient in calcium and/or phosphorus. Each group was divided into four subgroups which were offered distilled water supplemented with 0, 50, 75, or 150 ppm fluoride. High levels of fluoride in drinking water inhibited weight gain. This inhibition was less in rats deficient in phosphorus than when normal-phosphorus diets were offered. At a low level, fluoride was without any effect on bone ash, thickness of femoral cortical bone, and mechanical strength, as measured by maximal load, ultimate stress to breaking, and limit of elasticity. Modulus of elasticity was decreased. At higher levels fluoride tended to decrease most of these parameters, except in rats deprived of both calcium and phosphorus. The effect of fluoride was modified by lack of dietary calcium and/or phosphorus and appeared to be weaker in rats deficient in these nutrients. Lack of dietary calcium and/or phosphorus decreased bone strength more than did fluoride content of water and of bone mineral. Concentration of bone ash and thickness of femoral cortical bone were closely correlated with parameters of mechanical strength.
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  • 34
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    Skeletal radiology 1 (1977), S. 191-208 
    ISSN: 1432-2161
    Keywords: Vitamin D ; Rickets ; Osteomalacia ; Parathyroid hormone ; Skeleton ; Calcium ; Phosphorus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Major advances in the field of vitamin D metabolism have been achieved in the past decade that have considerably enhanced our understanding of a variety of metabolic bone diseases which include the rachitic and osteomalacic syndromes and parathyroid gland disorders. Delineation of the biochemical structure, metabolic pathways, mechanisms regulating synthesis, and physiologic functions has established that the compound should more appropriately be considered a hormone. Obligatory sequential, two-step hydroxylation of the prohormone, vitamin D, is necessary before physiologic action occurs. Initial hydroxylation occurs mainly in the liver while the second hydroxylation occurs exclusively in the kidney. The physiologically active form of the hormone, 1,25-(OH)2-D, coordinates with parathyroid hormone (and probably calcitonin) in promoting homeostasis of both extra-cellular calcium and phosphorus and the skeletal system. This article reviews the basic metabolism of vitamin D, the modes of physiologic action, the endocrine features of vitamin D and its relationship to parathyroid hormone, and discusses the important medical applications of this information.
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  • 35
    ISSN: 0570-0833
    Keywords: Phosphorus ylides ; Ylides ; Phosphorus ylides ; Synthetic methods ; Phosphorus ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Phosphacumulene ylides and phosphaallene ylides are nucleophilic compounds which can add reactants in a variety of ways. Cycloadditions can occur both at the polar C - P ylide bond and at the C=C double bond.
    Additional Material: 13 Tab.
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  • 36
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    Angewandte Chemie International Edition in English 16 (1977), S. 365-373 
    ISSN: 0570-0833
    Keywords: Flash thermolysis ; Thermolysis ; Synthetic methods ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Flash thermolysis is a special form of gas-phase thermolysis that is particularly suitable for the production and isolation of thermolabile reaction products. The theoretical basis and the instrumental requirements of the method are first given, and the preparative importance of flash thermolysis for the synthesis of thioketenes, allenes, arynes, highly strained ring systems, quinodimethanes, and other reactive compounds is then demonstrated with the aid of examples.
    Additional Material: 2 Ill.
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  • 37
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    Angewandte Chemie International Edition in English 16 (1977), S. 339-348 
    ISSN: 0570-0833
    Keywords: α-Metalated isocyanides ; Isocyanides ; Synthetic methods ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Being both nucleophilic and electrophilic, α-metalated isocyanides can add to polar double bonds, forming heterocycles. They are also synthons for α-metalated primary amines. This article describes recent or improved procedures for their use in organic synthesis: (1) In heterocyclic syntheses to give 2-oxazolines, 2-imidazolines, 2-thiazolines, oxazoles and oligooxazoles, thiazoles, triazoles, imidazolinones, pyrroles, 5,6-dihydro-1,3-oxazines and -thiazines, and (via cycloaddition with nitrones) 2-imidazolidinones. (2) In the field of formylaminomethylenation, for example transformation of estrone methyl ether and a keto sugar into the corresponding α-formylaminoacrylic esters, and the conversion of aldehydes and ketones by 3- and 4-pyridyl-methyl isocyanides into N-(1-pyridyl-1-alkenyl)formamides and their hydrolysis to 3- and 4-acylpyridines. (3) In connection with the use of α-metalated isocyanides as synthons for α-metalated primary amines, the author demonstrates how they may be used for preparation of 1,2- and 1,3-amino alcohols, 1,2-diamines, 2,3-diaminoalkanoic acids and for synthesis of higher amino acids starting from simple amino acids.
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  • 38
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    Angewandte Chemie International Edition in English 16 (1977), S. 493-505 
    ISSN: 0570-0833
    Keywords: Phase-transfer catalysis ; Catalysis ; Synthetic methods ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Phase-transfer catalysis (PTC) has grown into a versatile preparative method in the last few years. The most notable new developments include the use of crown ethers as phase-transfer catalysts and the introduction of solid-liquid PTC. Some representative examples have been selected from the large number of new PTC reactions and some of them are summarized in tables.
    Additional Material: 11 Tab.
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  • 39
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    Angewandte Chemie International Edition in English 16 (1977), S. 817-826 
    ISSN: 0570-0833
    Keywords: Titanium tetrachloride ; Synthetic methods ; Catalysis ; C-C coupling ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Titanium tetrachloride can accelerate numerous organic reactions. Valuable syntheses of, e.g., allyl sulfides, amides, enamines, and ketones are based upon transformations of functional groups with TiCl4. Particular mention should also be made of carbon-carbon linkage with TiCl4 which permits the synthesis of hydroxy ketones and carbonyl compounds of the Michael adduct type. TiCl4 reduced in situ is suitable for the reduction of chloroarenes or the linkage of two aldehyde molecules to give an alkene.
    Additional Material: 7 Tab.
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  • 40
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    Angewandte Chemie International Edition in English 16 (1977), S. 835-851 
    ISSN: 0570-0833
    Keywords: Cycloelimination ; Nitrogen cycloelimination ; Carbenes ; Heterocycles ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Cyclic azo compounds including heteroaromatics with a N=N bond of strong double-bond character can eliminate molecular nitrogen on addition of sufficient thermal energy or on electronic excitation. Some substrates decompose spontaneously, others are moderately or even extremely resistant to N2-elimination. From a preparative point of view this type of reaction opens a variety of interesting possibilities, e.g. the synthesis of small carbocycles or heterocycles, strained bi- and polycycles, as well as cage compounds. From a theoretical mechanistic viewpoint, current importance attaches to the primary fragments such as carbenes, diradicals, trimethylene, trimethylenemethane, dipoles, ylides, antiaromatic 4π-systems, unstable cycloalkynes, and arynes.
    Additional Material: 5 Ill.
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  • 41
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    Angewandte Chemie International Edition in English 16 (1977), S. 10-23 
    ISSN: 0570-0833
    Keywords: Cycloaddition ; Synthetic methods ; Intramolecular reactions ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Numerous examples of intramolecular cycloaddition of 1,3-dienes, nitrones, and azomethine imines attest the preparative value of this variant for regioselective and stereoselective synthesis of annelated and bridged ring systems. The common features, differences, and limitations of these types of reaction are systematically reviewed.
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  • 42
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    Hydrobiologia 50 (1976), S. 11-15 
    ISSN: 1573-5117
    Keywords: Phosphorus ; zooplankton excretion ; characterization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The characteristics of phosphorus excretions of zooplankton collected in spring 1974 from Stonehouse Pond, New Hampshire were studied with gel filtration, ultraviolet spectroscopy and seston incorporation. The soluble phosphorus component released from a natural population has a molecular weight the same as orthophosphate and behaves similar to orthophosphate in seston incorporation studies. Approximately 15 percent of the total phosphorus released was organic, but could not be identified by ultraviolet spectroscopy. No evidence of nucleic acid excretion or any hydrolytic degradation product was detected in the ultraviolet spectrum.
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  • 43
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    Angewandte Chemie International Edition in English 15 (1976), S. 1-9 
    ISSN: 0570-0833
    Keywords: Betaines ; Synthetic methods ; Cycloaddition ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The cycloadditions of 3-hydroxy-1-methylpyridinium betaines with electron-deficient olefins have been extended to a variety of 1-substituents in place of methyl. Application of resonance theory and later of quantum chemical methods led to rationalization of preceding results and prediction of new reactions. Thermal additions of 2π- and 6π-electron addends at the 2,6-positions and of 4π-electron addends at the 2,4-positions are described. The cycloadducts are highly interesting potential synthetic building blocks.
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  • 44
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    Angewandte Chemie International Edition in English 15 (1976), S. 333-340 
    ISSN: 0570-0833
    Keywords: Hydrozirconation ; Synthetic methods ; Zirconium ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Hydrozirconation has recently been developed as a procedure for functionalizing alkenes, alkynes, and 1,3-dienes via organozirconium(IV) intermediates. These intermediates react with a variety of electrophilic reagents to give organic products in high yield. Mechanisms of reactions involved in these sequences are discussed.
    Additional Material: 1 Ill.
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  • 45
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    Angewandte Chemie International Edition in English 15 (1976), S. 639-647 
    ISSN: 0570-0833
    Keywords: Addition ; Aldehydes ; Synthetic methods ; Esters ; Ketones ; Nitriles ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In the presence of cyanide ions as catalyst, aromatic and heterocyclic aldehydes can be smoothly added to α,β-unsaturated ketones, esters, and nitriles in aprotic solvents to form γ-diketones, 4-oxo carboxylic esters, and 4-oxo nitriles. Thiazolium salts in the presence of bases are also suitable catalysts; they permit not only addition of aromatic and heterocyclic aldehydes but also the addition of aliphatic aldehydes.
    Additional Material: 9 Tab.
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  • 46
    ISSN: 0570-0833
    Keywords: Synthetic methods ; Dihydrooxazoles ; Oxazoles ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The oxazoline ring system, first prepared in 1884, has only in the last five years been shown to possess considerable utility in the synthesis of a variety of functionalized organic compounds. By appropriate metalation of the 2-alkyl substituent it is possible to prepare a variety of homologated carboxylic acid derivatives, both chiral and achiral. Various other manipulations of the oxazoline ring lead to aldehydes, ketones, lactones, amino acids, thiiranes, and olefins. Due to the inertness of the oxazoline ring system to various reagents (RMgX, LiAlH4, CrO3, mild acid or alkali) it may be utilized as a protecting group for carboxylic acids during the transformations involving the above reagents. Two major new developments in oxazoline chemistry involve (a) the use of a chiral oxazoline as a reagent for asymmetric synthesis of chiral carboxylic acids, lactones, alcohol, thiiranes, and olefins and (b) a new mode of aromatic substitution in which the aryloxazolines act as nucleophilic or electrophilic reagents. This behavior has led to a variety of polysubstituted benzenes and biphenyls which would be inaccessible by classical routes. A variety of examples illustrating the utility of oxazolines indicated above are presented so that the reader may appreciate the vast potential of this simple ring system in synthesis.
    Additional Material: 15 Tab.
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  • 47
    ISSN: 0570-0833
    Keywords: Halomalondialdehydes ; Malondialdehydes ; Synthetic methods ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The present progress report provides a survey of the synthesis, structure, and reactions of halomalondialdehydes, including “cyanomalondialdehyde” (diformylacetonitrile), the only pseudohalogen compound so far known in this series. Halomalondialdehydes are reactive compounds, applicable in a variety of ways, and are characterized particularly by their cyclizations with bifunctional compounds. Many of the reactions discussed below can be applied to substituted malondialdehydes other than those specified.
    Additional Material: 1 Ill.
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  • 48
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    Angewandte Chemie International Edition in English 14 (1975), S. 734-745 
    ISSN: 0570-0833
    Keywords: Substitution ; Radical ions ; Intermediates ; Synthetic methods ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A new type of substition process at a saturated carbon atom is described. These reactions, which proceed via a chain sequence in which radical anions and free radicals are intermediates, are noteworthy for providing novel and powerful means of synthesis: they occur readily under mild conditions, they give excellent yields of pure products, and, in contrast to SN2 displacements, they are rather insensitive to steric hindrance. As a consequence, radical anion processes are especially valuable for the preparation of highly branched structures. Many inorganic and organic anions readily enter into these displacements and, indeed, amines are also effective. Systems which undergo substitutions via this electron transfer mechanism include benzylic, cumylic, strictly aliphatic, and heterocyclic molecules. It is of interest that a number of groups which do not behave as leaving groups in SN2 displacements are readily displaced at room temperature from a satureted carbon atom via the radical anion-free radical pathway, e.g., nitro, azide, sulfone, and ether groups.
    Additional Material: 3 Tab.
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  • 49
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    Angewandte Chemie International Edition in English 14 (1975), S. 222-231 
    ISSN: 0570-0833
    Keywords: Phosphorylcarbenes ; Carbenes ; Synthetic methods ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Phosphorylcarbenes, which have become known only recently during synthetic experiments in the field of phosphoryldiazoalkanes, have twofold preparative value. In the first place, they can be used to introduce phosphoryl groups into organic compounds, as in the phosphoryl-cyclopropanation of alkenes or arenes and in the phosphorylcyclopropenation of alkynes. Secondly, phosphorylcarbenes readily undergo rearrangements; hydride, alkyl, aryl, or acyl shifts lead to phosphorylated alkenes. The phosphorylcarbene/methylenephosphane oxide rearrangement provides access to the short-lived P analogs of the ketenes. Finally, the vinylcarbene/allene rearrangement was first discovered in this connection; it competes with ring closure to the cyclopropene.
    Additional Material: 11 Tab.
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  • 50
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    Angewandte Chemie International Edition in English 14 (1975), S. 473-485 
    ISSN: 0570-0833
    Keywords: Ring contraction ; Cyclobutanes ; Cyclopropylmethyl compounds ; Ring expansion ; Synthetic methods ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Cyclobutanes and cyclopropylmethyl compounds vicinally disubstituted in appropriate manner by one electron-donating group and one leaving or electron-receiving group undergo extremely facile ring contractions and expansions respectively. Unlike many rearrangements of small-ring compounds and most rearrangements of larger-ring compounds, these reactions usually give a single product in high yield and thus possess real synthetic interest. The subject matter of this progress report is classified according to the substituents in question since the nature of these groups largely determines the conditions under which rearrangement takes place.
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  • 51
    ISSN: 0570-0833
    Keywords: Heterocycles ; Aromaticity ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The terms “aromatic” and “antiaromatic” have attracted widespread interest in recent years. After all the discussion about the meaning of words, one fact remains: the energy content of planar systems displaying cyclic electron delocalization depends upon the number of, and the orbital interactions between, the participating electrons. The concept underlying this progress report is that the electronic destabilization of systems having eight π-electrons should be especially pronounced in the case of six-membered rings for steric and electronic reasons. Such systems are found primarily in anionic, but also in neutral, heterocycles containing hetero ring members which possess electron pairs capable of delocalizing into the π-system. The production and reactivity of such systems are investigated and their biological significance discussed.
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  • 52
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    Angewandte Chemie International Edition in English 14 (1975), S. 232-245 
    ISSN: 0570-0833
    Keywords: Antimony ; Arsenic ; Bismuth ; Boron ; Germanium ; Phosphorus ; Silicon ; Bond theory ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Recent years have seen the preparation of π systems containing novel (p-p)π bonds between carbon and elements from the third, fourth, and fifth Main Groups of the Periodic Table; most of these compounds are predicted to be incapable of existence according to the classical concepts of the double bond. (p-p)π. Bonds between carbon and phosphorus, arsenic, and antimony have been successfully stabilized in resonance-stabilized colored compounds of the cyanine and triphenylmethane type, and also in aromatic systems deriving from benzene, naphthalene, and anthracene. Bismuth-carbon and boron-carbon (p-p)π bonds have likewise been confirmed in aromatic systems. Silicon-carbon and germanium-carbon (p-p)π bonds have been detected in extremely reactive derivatives of silaethylene and germaethylene, respectively. The present report describes characteristic reactions of the new π systems. Their bonding follows from X-ray structure analysis, from photoelectron, UV, and NMR spectra, and from calculations. Criteria for the existence of π systems which are not allowed by the classical double bond rule are discussed; these criteria remain valid on generalization.
    Additional Material: 6 Ill.
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  • 53
    ISSN: 0570-0833
    Keywords: Umpolung ; Nitrosamines ; Amines ; Synthetic methods ; Nucleophilic reactions ; Aminoalkylation ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: There are basically two kinds of hetero atoms in organic molecules: one kind confers electrophilic character upon the carbon atom to which it is bound, and the other kind turns it into a nucleophilic site. The development of methods permitting transitions between the two resulting categories of reagents has become an important task of modern organic synthesis. The scope of such umpolung of the reactivity of functional groups is discussed for the case of amines as an example. A method of preparing masked α-secondary amino carbanions consists in nitrosation of the secondary amine, followed by metalation of the resulting nitrosamine α-to the nitrogen, reaction with electrophiles, and subsequent denitrosation. Many examples are given for each of these steps which illustrate the wide scope of the overall synthetic operation (electrophilic substitution at the α-C atom of the secondary amine). Preliminary applications and a method for avoiding the handling of nitrosamines are presented, and the report concludes with a brief account of the significance of nitrosamines in the study of carcinogenesis and mutagenesis.
    Additional Material: 1 Ill.
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  • 54
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    Angewandte Chemie International Edition in English 14 (1975), S. 665-679 
    ISSN: 0570-0833
    Keywords: Heterocycles ; Optical brighteners ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Optical brighteners are used in detergents, textiles, paper, plastics, and paints. Most optical brighteners contain heterocycles such as coumarins, 2-pyrazolines, naphthalimides, pyrazoles, triazoles, oxadiazoles, and triazines. In this article the syntheses, properties, and applications of new optical brighteners are described with references to patent literature.
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  • 55
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    Angewandte Chemie International Edition in English 14 (1975), S. 801-811 
    ISSN: 0570-0833
    Keywords: Tetrachloromethane ; Phosphanes ; Chlorination ; Dehydration ; Synthetic methods ; Phosphorus-nitrogen compounds ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In this review the processes occurring on the treatment of triphenylphosphane with tetrachloromethane are first reported; a key role is played here by (trichloromethyl)phosphonium chloride which reacts with a further amount of the phosphane to give the stable salt [chloro(triphenylphos-phoranediyl)methyl]triphenylphosphonium chloride by way of dichlorophosphorane and (dichloromethylene)phosphorane that is detectable only as an intermediate. The preparative application of the two-component system as a chlorinating, dehydrating, and P - N-linking reagent is ascribable to “phosphorylation”Here and below, “phosphorylation” is used lo mean in general the formation of a phosphorus derivative. In the narrower sense this term denotes the introduction of phosphoryl groups P(O). of the substrate in question through several reactive species. In these applications the reactions with the substrate compete with reactions of the two-component system with itself, so that the overall course of the reaction is in nearly all cases much more complex than was previously assumed. Nevertheless. very good results can be achieved by the use of this reagent, high yields and mild reaction conditions being characteristic.
    Additional Material: 1 Tab.
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  • 56
    ISSN: 0570-0833
    Keywords: Phosphinidenes ; Phosphanediyl compounds ; Heterocycles ; Cyclophosphanes ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Formation and detection of phosphinidenes (R—P̈:) in the decomposition of cyclophosphanes and in the reaction of dichlorophosphanes with metals are considered critically. Only in the thermolysis of pentaphenylcyclopentaphosphane can phenylphosphinidene be detected with certainty by pyrolysis-mass spectroscopy. “Trapping reactions” such as “insertion” into S—S or As—As bonds, and addition reactions with 1,2-diketones, 1,3-dienes, or alkynes can also be interpreted without the assumption of free phosphinidenes. The pyrolysis products of cyclophosphanes add to 1,3-dienes and alkynes, yielding five- and six-membered heterocycles that contain one to three phosphorus atoms.
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  • 57
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    Angewandte Chemie International Edition in English 14 (1975), S. 528-538 
    ISSN: 0570-0833
    Keywords: Bredt rule ; Bridgehead alkenes ; Synthetic methods ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: During the past eight years, bridgehead olefins have attracted rapidly increasing attention. In view of their significance with regard to the stereochemistry of alkenes, the study of certain reaction mechanisms, and the nature of the double bond, detailed research into this structural type appears highly desirable. Bridgehead olefins represent connective linkages between olefins in the ground state and species which can arise in the deactivation of photochemically excited alkenes and cycloalkenes and also contribute to our understanding of the structural conditions prevailing during cis-trans isomerization of alkenes.
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  • 58
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    Calcified tissue international 16 (1974), S. 139-144 
    ISSN: 1432-0827
    Keywords: Dental enamel ; Iron ; Calcium ; Phosphorus ; Electron probe
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Abstract Using electron microprobe analysis, the surface layer of enamel of rat maxillary incisors was found to contain 10–30% Fe. The Ca and P concentrations in different areas of the enamel surface varied inversely with the Fe concentration. The Ca/P weight ratio was 1.8 in areas containing 10% Fe, but decreased to 1.0 in the most Fe-rich areas. The Fe concentration was highest at the prism boundaries, whereas the maximum concentrations of Ca and P were found within the enamel prisms. The concentrations of Fe in rat incisor enamel are among the highest values reported for any mineralized tissue.
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  • 59
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    Calcified tissue international 15 (1974), S. 111-123 
    ISSN: 1432-0827
    Keywords: Fluoride ; Calcium ; Phosphorus ; Bone ; Periosteum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Description / Table of Contents: Résumé Une méthode d'estimation de la surface périostée de l'os en voie de minéralisation est mise au point et appliquée à des porcs recevant 2 mg de fluorure par Kg de poids et par jour pendant 10 mois. L'adjonction de fluor intervient significativement dans le cas d'une déficience en calcium et phosphore. La surface en voie de minéralisation est nettement réduite. Lorsque le calcium et phosphore sont normaux, l'addition de fluorure augmente nettement la surface en voie de minéralisation. Le microscope électronique à balayage permet de mettre en évidence au niveau de l'os une perte de l'orientation longitudinale des fibers et des surfaces poreuses irrégulières chez les animaux soumis au floor.
    Abstract: Zusammenfassung Zur Bestimmung der verkalkenden Oberfläche des Periosts wurde eine Methode entwickelt und bei Schweinen angewandt, welche während etwa 10 Monaten 2 mg Fluorid per kg Körpergewicht und per Tag erhalten hatten. Dieses zusätzliche Fluorid hatte eine signifikante Wirkung bei Calcium- und Phosphormangel. Die verkalkende Oberfläuche ging stark zurück, während jedoch, wenn kein Calcium- und Phosphormangel bestand, das zusätzliche Fluorid die verkalkende Oberfläche vergrößerte. Beobachtungen mit dem Raster-Elektronenmikroskop am Knochen zeigten, daß die Längsorientierung der Fasern fehlte und daß Knochen von mit Fluorid gefütterten Tieren unregelmäßige, poröse Oberflächen aufwiesen.
    Notes: Abstract A method for estimating periosteal bone-mineralizing surface was developed and applied to swine fed 2 mg of fluoride/kg of body weight/day for about 10 months. Added fluoride interacted significantly with calcium and phosphorus deficiency. Mineralizing surface was greatly reduced, whereas when calcium and phosphorus were adequate, added fluoride greatly increased mineralizing surface. Scanning electron microscope observations of bone disclosed loss of longitudinal orientation of fibers and irregular porous surfaces in bone from fluoride-fed animals.
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  • 60
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    Calcified tissue international 15 (1974), S. 181-188 
    ISSN: 1432-0827
    Keywords: Biopsy ; Bone ; Calcium ; Phosphorus ; Specific gravity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Abstract The specific gravities (SG) of bone samples taken from various parts of the skeleton of cattle and sheep were determined gravimetrically in an effort to establish which sites give the most reproducible and uniform results, so that between animals, or sequential within animals, comparisons may be made with maximum sensitivity. Samples obtained from the mandible of sheep and the rib of cattle and sheep were found to be too variable to be useful for most purposes. Best results were obtained using whole bones which are easily prepared, such as the tibial tarsal bones of cattle and sheep and the fibular tarsal bone of cattle. These bones gave within animal deviations of 0.012–0.024 SG units, when comparing left bone with right bone. Slightly higher values were obtained for coccygeal vertebrae from cattle and distal metacarpal condyles from sheep. SG was related to ash, calcium and phosphorus contents of coccygeal vertebrae of cattle and it is considered that, for survey work on the mineral status of the bones of cattle and sheep, the correlations are sufficiently high to make their determination unnecessary. This will enable radiation determined SG techniques to be applied to this type of work.
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  • 61
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    Angewandte Chemie International Edition in English 13 (1974), S. 627-639 
    ISSN: 0570-0833
    Keywords: Cycloaddition ; Organolithium compounds ; Synthetic methods ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In the field of [3 + 2]-cycloaddition reactions, 1,3-anionic cycloadditions have now joined 1,3-dipolar cycloadditions as a second reaction type of major general importance. The cycloaddition in question has been found to occur with 2-azaallyllithium compounds, allyllithium compounds (with an electron acceptor located on C2), and 1,3-diphenylpropargyllithium. Compounds with CC, CN, NN, and CS double bonds and those with CC and CN triple bonds were found to be 1,3-anionophilic. 1,3-Anionic cycloaddition opens new routes to 1-aza-, 1,2-diaza-, 1,3-diaza-, 1,2,4-triaza-, and 1-thia-3-azacyclopentane derivatives, to pyrroles and imidazoles, as well as (and this appears to be of special importance) to cyclopentane derivatives. Currently available data attribute stereospecificity to the 1,3-anionic cycloadditions, which occupy an interesting intermediate position between 1,3-dipolar cycloadditions and transition-metal-catalyzed cyclizations. A two-step mechanism has been demonstrated in one case.
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  • 62
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    Angewandte Chemie International Edition in English 13 (1974), S. 520-533 
    ISSN: 0570-0833
    Keywords: Halovinylene carbonates ; Vinylene carbonates ; Synthetic methods ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Monohalo- and dihalovinylene carbonates constitute a new class of cyclophiles which permit simultaneous introduction of masked α-hydroxyketo and α-diketo functions, respectively, into the cycloadducts. Demasking can be performed by simple hydrolysis. Solvolytic opening of the carbonate ring leads to glycolic acid derivatives in the case of the monohalo compounds and to glyoxylic acid derivatives with the dihalo compounds. Preparation of the title compounds, their potential as synthetic reagents, and the chemistry of their simple reaction products are surveyed from a preparative viewpoint.
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  • 63
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    Angewandte Chemie International Edition in English 13 (1974), S. 701-706 
    ISSN: 0570-0833
    Keywords: Organometallic compounds ; C-C coupling ; Copper ; Potassium ; Synthetic methods ; Sodium ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Merits and drawbacks of known carbon-carbon linking procedures are outlined. Two novel methods are discussed in some detail: the copper-catalyzed alkylation of Grignard reagents and reactions with allylpotassium compounds. Both methods provide a very efficient access to saturated, unsaturated, as well as functionally substituted hydrocarbons and moreover permit an astonishing degree of regio- and stereoselective control of olefin synthesis.
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  • 64
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    Angewandte Chemie International Edition in English 13 (1974), S. 491-504 
    ISSN: 0570-0833
    Keywords: Carbon suboxide ; Synthetic methods ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Although it has been known for nearly 70 years, carbon suboxide was used almost exclusively for the preparation of simple malonic acid derivatives until about 1960. Since then, however, the significance of this unusual “bisketene” has steadily increased in synthetic chemistry (especially that of heterocyclic compounds). This progress report surveys the possible applications of C3O2 in preparative organic chemistry, including photochemical reactions.
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  • 65
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    Angewandte Chemie International Edition in English 13 (1974), S. 619-627 
    ISSN: 0570-0833
    Keywords: Cyclic peroxides ; Peroxides ; Synthetic methods ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The photodecarboxylation of malonyl peroxides into α-lactones[1] and the thermal conversion of the 1,4-endo-peroxide 4,5-epoxy-3,6-epidioxy-1-cyclohexene into the novel benzene trioxide[2] are two recent examples of the potential of cyclic peroxides in the synthesis of unusual organic molecules. The former transformation entails a fragmentation, the latter a rearrangement process. Most reported examples fall into one of these two gross reaction types. Of the numerous examples that have been reported in the literature during the last two decades, only those shall be focused on that lead to unusual compounds or constitute efficient syntheses of known compounds, in order to stress the convenience of cyclic peroxides in the synthesis of organic compounds.
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  • 66
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    Angewandte Chemie International Edition in English 13 (1974), S. 789-804 
    ISSN: 0570-0833
    Keywords: Isocyanides ; Synthetic methods ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: α-Alkali-metalated isocyanides, which can be obtained from isocyanides and bases, can be used for nucleophilic introduction of (masked) α-aminoalkyl groups. Intramolecular ring-closure may then follow if a nucleophile combines at the electron sextet of the isocyanide carbon. Treatment of α-alkali-metalated isocyanides with electrophilic agents permits rapid and efficient synthesis of, inter alia, 2- and 3-amino alcohols, straight-chain, branched, and β-functional α-amino acids, olefins, vinyl isocyanides, and of a large number of mainly five-, but also six- and seven-membered aza-, diaza-, oxa-aza-, and thia-aza heterocycles.
    Additional Material: 1 Ill.
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  • 67
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    Angewandte Chemie International Edition in English 13 (1974), S. 170-179 
    ISSN: 0570-0833
    Keywords: Phase-transfer catalysis ; Catalysis ; Synthetic methods ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Quaternary ammonium and phosphonium salts catalyze reactions between substances located partly in an aqueous and partly in an organic phase. Use of such phase-transfer catalysts simplifies and accelerates numerous reactions traditionally conducted in nonaqueous media. These reactions include carbene reactions, nucleophilic substitutions, alkylations of ketones and nitriles, Wittig and Darzens reactions, formation of ethers and esters. Other reactions such as hydrolysis and oxidation can be accelerated.
    Additional Material: 5 Tab.
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  • 68
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    Calcified tissue international 12 (1973), S. 259-279 
    ISSN: 1432-0827
    Keywords: Osteocyte ; Calvarium ; Histology ; Development ; Calcium ; Phosphorus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Description / Table of Contents: Résumé Des cartes tissulaires ainsi que les caractéristiques et propriétés cellularires ont été relevées au cours d'une étude de microscopie optique du développement de la calotte cranienne de souris, avant la naissance, jusqu'au 26ème jour. Les population d'ostéocytes de moitiés droite et gauche de ces calottes sont semblables, mais décroissent avec le temps dans un volume donné. De petites plages limitées de matrice osseuse se colorent pour le phosphate (ou carbonate) de façon plus nette que la matrice environnante, qui se colore légèrement après coupe. Les divers types ostéocytaires se distinguent par les réactions histochimiques du calcium et du phosphate, qui sont associés dans les cellules osseuses de façon complexe, variant dans le temps et la localisation. Ces deux constituants ne sont pas toujours présent dans les cellules des diverses régions, ou dans la même localisation dans un type cellulaire donné. En tenant compte des changements visible dans les divers types cellulaires avec le temps, dans des régions données, une hypothèse de “charge” et “décharge” cellulaire est émise.
    Abstract: Zusammenfassung Anläßlich einer mikroskopischen Studie über die Entwicklung des Mäuse-Calvariums von der Pränatalperiode bis zu 26 Tagen nach der Geburt wurden auch die Gewebetopographie sowie die Charakteristica und Eigenschaften der Zellen aufgezeichnet. Die Osteocyten-populationen in der linken und rechten Hälfte des Calvariums waren sich gleich, nahmen jedoch bei einem gegebenen Volumen mit der Zeit ab. Kleine isolierte Stellen von Knochen-matrix konnten leichter auf Ph sphat (oder Carbonat) angefärbt werden, als die umgebende Matrix, welche sich wohl am Schnitt, nicht aber am ganzen Stück färben ließ. Die verschiedenen Typen von Osteocyten wurden aufgrund histochemischer Calcium- und Phosphat-reaktionen bestimmt. Calcium und Phosphat waren innerhalb der Knochenzellen auf komplexe Art miteinander verbunden, die je nach Zeit und Lagerung unterschiedlich war. Zellen in abgetrennten Bereichen enthielten nicht immer Calcium und Phosphat und beide waren bei einer bestimmten Zellenart auch nicht immer am gleichen Ort abgelagert. Aufgrund der an ausgewählten Stellen beobachteten, zeitlich bedingten Veränderungen innerhalb der verschiedenen Zelltypen wird vorgeschlagen, daß es sich dabei um eine Sequenz von “Ladung” und “Entladung” der Zellen handelt.
    Notes: Abstract Tissue maps, and cell characteristics and properties were recorded in a study under the optical microscope of the development of the mouse calvarium from pre-natal to 26 days. Osteocyte populations in left and right halves of the calvarium were similar, but decreased with time for a given volume. Small isolated areas of bone matrix stained for phosphate (or carbonate) in a more readily available form from that in the surrounding matrix, which could be stained after sectioning but failed to stain in bulk. Osteocyte types were defined on the basis of histochemical methods for calcium and phosphate, which were associated inside bone cells in a complex manner, varying with time and position. The calcium and phosphate were not always present within the cell in discrete regions and were not always present in the same place in a given cell type. On the basis of a study of changes in cell types with time in selected sites a sequence of “loading” and “unloading” is proposed.
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  • 69
    ISSN: 0570-0833
    Keywords: Displacement reactions ; Phosphorus ; Phosphorus ; Reaction mechanisms ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Reactions of phosphorus(v) compounds involving the mutual interconversion of tetra- and pentacoordinate species are discussed in a critical review emphasizing stereochemical implications of the reaction mechanism. This discussion includes the formation and decomposition of the stable oxyphosphoranes, the Michaelis-Arbusov, Perkov, and Wittig reactions, interconversions of phosphines and their oxides, and the nucleophilic displacements on phosphonium compounds. Reactions of phosphate esters and related compounds receive particular attention. All chemical arguments are derived by considering the effect of factors determining the relative stabilities of phosphorane derivatives, their rates of formation, decomposition and rearrangement by bond deformation or rupture and recombination processes, considerations which are uniformly applied on the basis of concepts developed in a preceding communication[2]. It is shown that a comprehensive mechanistic interpretation of the foregoing reactions requires substantial addition to available conceptual foundations such that, in many cases, present concepts and mechanisms must be revised.
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  • 70
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    Angewandte Chemie International Edition in English 12 (1973), S. 119-126 
    ISSN: 0570-0833
    Keywords: Heterocycles ; Intramolecular reactions ; Acylation ; Nitrile hydrogen halide adducts ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Five-membered, six-membered, and seven-membered aza-, diaza-, and thiazaheterocycles can be prepared by cyclization of. ω-cyano carboxylic acid halides in the presence of hydrogen halides in aprotic solvents. Nitrile-hydrogen halide adducts occur as intermediates in this novel heterocycle synthesis of wide application. The acylating cyclizations of nitriles in protonic media, which proceed via imidic esters or amides, are not discussed.
    Additional Material: 9 Ill.
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  • 71
    ISSN: 1432-0827
    Keywords: Phosphorus ; Intestine ; Absorption ; Rickets ; Vitamin D
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Description / Table of Contents: Résumé L'autoradiographie en microscopie électronique est utilisée pour déterminer la distribution du phosphore dans les cellules d'absorption du duodénum pour déterminer si une différence existe entre le rat rachitique, le rat normal et le rat rachitique traité par vitamine D. Pas de différence notable n'est observée en répartition de phosphate entre les groupes, mais l'animal rachitique obsorbe du phosphore et tous les groupes présentent une répartition différente de celle du calcium. On note un marquage des microvillosités, de l'appareil terminal de jonction, des mitochondries, du noyau, des vesicules denses et claires, ainsi que de l'ergastoplasme lisse et rugueux.
    Abstract: Zusammenfassung Die elektronenmikroskopische Autoradiographie wurde verwendet, um die Verteilung von Phosphor in den absorbierenden Zellen des Duodenum zu bestimmen und um jeglichen Unterschied festzustellen, der zwischen rachitischen, normalen und Vitamin D-behandelten rachitischen Ratten bestehen könnte. Die Phosphatverteilung variierte nur wenig zwischen den verschiedenen Diät-Gruppen, hingegen konnte das rachitische Tier Phosphat absorbieren, und alle Gruppen zeigten eine Verteilung, welche von derjenigen des Calciums abwich. Die Markierung konnte auf den Microvilli, dem Terminalgeflecht, den Mitochondrien, dem Zellkern, den hellen und dichten “core vesicles” (=Vesikeln mit hellem und dichtem Kern) und dem glatten und rauhen endoplasmatischen Reticulum gesehen werden.
    Notes: Abstract Electron microscopic autoradiography was utilized to determine the distribution of phosphorus within the absorptive cells of the duodenum and to determine any difference that might exist between the rachitic, normal and vitamin-D-treated rachitic rat. No great difference was noted in phosphate distribution among the various nutrition groups, but the rachitic animal was able to absorb phosphorus and all groups demonstrated a distribution different from that of calcium. Label was seen over the microvilli, terminal web, mitochondria, nucleus, dense and light core vesicles, as well as smooth and rough endoplasmic reticulum.
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  • 72
    ISSN: 1432-0878
    Keywords: C cells ; Sheep ; Calcitonin ; Calcium ; Phosphorus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Description / Table of Contents: Résumé Les recherches combinées qualitatives et quantitatives indiquent chez la Brebis, et contrairement aux résultats acquis chez la Vache, que la parturition n'est pas accompagnée d'une décharge plus ou moins intense de calcitonine. La Brebis parturiente ne montre aucune variation significative de la calcémie et de la phosphatémie; sa thyroïde renferme des taux de calcitonine analogues à ceux rencontrés chez des brebis taries, non gestantes. Dans les mêmes conditions, l'examen au microscope électronique des cellules C permet encore de rendre compte d'activités de synthèse, de sécrétion et d'excrétion tout à fait normales.
    Notes: Summary A combination of qualitative and quantitative studies show that there is not an abrupt release of calcitonin at the time of parturition in the ewe; these results differ from those obtained by several authors in the parturient cow. At lambing time, ewes are neither hypocalcemic nor hypophosphatemic; thyroidal calcitonin content is similar in parturient and in dry non-pregnant ewes. In electron microscopic studies, synthesis and release of calcitonin from C-cells in ewes, slaughtered in the hours just after lambing, appear to be as usual. These results are discussed with regard to the syndrome of parturient paresis in ruminants.
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  • 73
    ISSN: 0570-0833
    Keywords: Conformation analysis ; Heterocycles ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: This review deals with the following aspects of conformational analysis in saturated heterocyclic systems: 1. Conformational equilibria in 2-aryl and 2-ethynyl-1,3-dioxanes in various solvents. 2. The generalized anomeric effect in perhydro-1,3-diazines and its origin. 3. Unexpected conformational equilibria in 5-heterosubstituted 1,3-dioxanes. 4. Normal and anomalous solvent effects in conformational equilibria of 1,3-dioxanes with heteroatoms at C-5. Calculation of solvent effects. Correlation of ΔG0 as a function of solvent with solvatochromic transition energy ET (30); a new scale of “solvent polarity”. 5. Interplay of hydrogen bonding with dipolar, non-bonded and eclipsing interactions in 5-hydroxymethyl- 1,3-dioxanes. 6. Highly stereoselective H-D exchanges in anancomeric 1,3-dithianes. 7. Potential distortion of a cyclohexane or 1,3-dioxane ring by a tert-butyl substituent. Evidence from 1H-NMR and 13C-NMR investigations and from X-ray structure analysis.
    Additional Material: 5 Ill.
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  • 74
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    Angewandte Chemie International Edition in English 11 (1972), S. 949-963 
    ISSN: 0570-0833
    Keywords: Cyanic esters ; Heterocycles ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The reactions of cyanic esters with acylating agents and the reactions of the resulting N-acyliminocarbonic ester halides are surveyed, and syntheses of heterocycles with cyanic esters and their reaction products are then reported.
    Additional Material: 4 Tab.
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  • 75
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    Calcified tissue international 8 (1971), S. 24-35 
    ISSN: 1432-0827
    Keywords: Bone ; Cartilage ; Epiphysis ; Calcium ; Phosphorus ; Vitamin D
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Description / Table of Contents: Résumé Les électrolytes ont été analysés dans le sérum et dans les tissues en voie de minéralisation, à des stades variables de calcification, chez des poulets et des pores normaux et rachitiques. L'humidité, les cendres et les matières organiques et déssèchées ont été analysées. Il apparait que d'autres électrolytes sériques, en plus du Ca, sont modifiés au cours du rachitisme. Le Mg et le P inorganique sont modifiés de façon variable au cours de l'avitaminose D. Des changements plus importants en contenu minéral des tissus sont observés dans les stades précoces de calcification que ceux que l'on a pu constater dans le sérum à des stades similaires, ce qui suggère un effet direct de l'avitaminose sur le tissu en voie de calcification. Quant au contenu du sérum, le dépôt de Ca est plus élevé dans les tissus d'animaux rachitiques par rapport aux témoins. Ceci n'est pourtant pas le cas du Mg ou du P inorganique, indiquant une affinité préférentielle du Ca pour le tissue rachitique. L'analyse gravimétrique de matières organiques et déssèchées des zones épiphysaires montre que les quantités de cartilage hypertrophique et en voie de dévelopment augmentent dans le cas de rachitisme, alors que le cartilage calcifié diminue, confirmant les observations histologiques antérieures. De manière inattendue, la proportion de cartilage au repos augmente au cours du rachitisme.
    Abstract: Zusammenfassung Die Elektrolyte im Serum und in mineralisierenden Geweben wurden zu verschiedenen Zeitpunkten der Verkalkung bei normalen Hühnern und Schweinen und bei solchen mit Vitamin D-Mangel analysiert. Wassergehalt, Asche, trockene und organische Substanz wurden ebenfalls gemessen. Die Ergebnisse zeigten, daß außer Ca auch andere Elektrolyte bei Rachitis verändert wurden. Mg und anorganischer P wurden durch den Vitaminmangel bei den beiden Gattungen verschiedenartig beeinflußt. In den Geweben wurde in den frühen Phasen der Verkalkung eine größere Änderung des Mineral-Spiegels gefunden, als dies zu übereinstimmenden Zeiten im Serum der Fall war, was auf eine direkte Wirkung des Vitaminmangels auf das verkalkende Gewebe schließen läßt. Im Verhältnis zum Serumspiegel wurde Ca in den Geweben der rachitischen Tiere zu einem größeren Grade als normal abgeschieden. Dies war nicht der Fall bei Mg oder anorganischem P, was einen Vorzug für Ca in den rachitischen Geweben anzeigt. Gravimetrische Analysen von organischer und trockener Substanz in epiphysischen Schichten zeigten, daß die Menge des proliferierenden und hypertrophischen Knorpels zunahm und daß verkalkter Knorpel bei Rachitis abnahm, gemäß klassischen histologischen Beobachtungen. achtungen. Ganz unerwartet war bei Rachitis eine verhältnismäßige Zunahme des ruhenden Knorpels festzustellen.
    Notes: Abstract Electrolytes were analyzed in serum, and in mineralizing tissues at varying stages of calcification, in normal and vitamin D-deficient chickens and pigs. Moisture, ash, and organic matter were also measured. Results revealed that in addition to Ca, other serum electrolytes were altered in rickets. Mg and inorganic P were diversely affected by the vitamin deficiency. Larger changes in mineral level were seen in the tissues in the early stages of calcification than were seen at corresponding times in the serum, suggesting a direct effect of the vitamin deficiency on the calcifying tissue itself. Relative to the serum level, Ca was deposited in the tissues of rachitic animals to a greater extent than in normal animals. This was not true for Mg or inorganic P, indicating a preferential affinity for Ca in the rachitic tissue. Gravimetric analyses of organic and dry matter in epiphyseal zones revealed that the amounts of proliferating and hypertrophic cartilage were increased, and calcified cartilage decreased, in rickets, in accord with previous histological observations. Unexpectedly, the proportion of resting cartilage was also increased.
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  • 76
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    Calcified tissue international 8 (1971), S. 73-82 
    ISSN: 1432-0827
    Keywords: Bone ; Calcium ; Phosphorus ; Sodium ; Magnesium ; Electron probe
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Description / Table of Contents: Résumé L'analyse par microsonde électronique, technique récente, a été peu utilisée pour l'étude du tissu osseux. Le rapport molaire Ca/P a été mesuré pour l'os normal et certains os pathologiques. Les résultats sont en accord avec ceux obtenus par les autres méthodes, en particulier la microradiographie. La microsonde électronique permet le dosage du sodium et du magnésium, constituants secondaires de l'os, à l'échelle microscopique. Nos observations mettent en évidence l'hétérogénéité de la distribution de ces éléments: concentration élevée dans l'os jeune (ostéone), moindre dans l'os interhaversien. Ces résultats sont en accord avec l'hypothèse de Neuman de l'absorption des ions sodium et magnésium à la surface du crystal d'apatite.
    Abstract: Zusammenfassung Die Mikroanalyse mittels Elektronensonde ist eine neue Technik für die Untersuchung von Knochen; die Bedingungen für eine richtige Interpretation der Resultate werden beschrieben. Das molare Ca/P-Verhältnis wurde in normalen und in drei pathologischen Knochen gemessen. Diese Messungen wurden in verschiedenen Regionen des corticalen Knochens durch-geführt. Die Resultate stimmen mit den durch Mikroradiographie erhaltenen überein. Mikroanalysen mittels der Elektronensonde ermöglichten es, die Verteilung von Na und Mg in den zwischenhaversschen und haversschen Geweben von corticalem Knochen Erwachsener zu untersuchen. Unsere Beobachtungen zeigen die heterogene Verteilung dieser Elemente. In Übereinstimmung mit der Hypothese der Ionen-Absorption an der Oberfläche des Apatitkristalles sind die Konzentrationen in jungen Knochen (Oesteonen) höher.
    Notes: Abstract Electron probe microanalysis is a recent technique for the study of bone and the conditions for the correct interpretation of the results are described. The Ca/P molar ratio was measured in normal and in three pathological bones. These measurements were carried out in different regions of cortical bone. The results are in agreement with the results obtained by microradiography. Microprobe analysis, however, allows the measurement of elements at the microscopic level. Electron probe microanalysis was used to study the distribution of sodium and magnesium in the interhaversian and haversian tissues of adult cortical bone. Observations show the heterogeneity of distribution of these elements. Concentrations are higher in young bone (osteons), in agreement with the hypothesis of ion absorption on the surface of the apatite crystal.
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  • 77
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    Clinical and experimental medicine 156 (1971), S. 61-66 
    ISSN: 1591-9528
    Keywords: Bone resorption ; Phosphorus ; Parathyroid hormone
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The effect of a low phosphorus diet on bone resorption is studied in thyroparathyroidectomized rats. Bone resorption is estimated from the marrow cavity area of a cross-section of the tibia. The rate of calcium mobilisation from bone is estimated by serum specific activity of45Ca/40Ca after labelling of the diet. Bone resorption is increased by feeding a low phosphorus diet, suggesting a direct effect of hypophosphatemia stimulating bone resorption, independent of any action of parathyroid hormone.
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  • 78
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    Angewandte Chemie International Edition in English 10 (1971), S. 20-33 
    ISSN: 0570-0833
    Keywords: Hetarynes ; Heterocycles ; Alkynes ; Arynes ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: During recent years, instead of concentrating on the detection of the intermediacy of new hetarynes, as they did between 1958 and 1964, workers in this field have been more concerned with the critical sifting and checking of the earlier work. Special interest has been shown in the relation between structure and reactivity in the hetarynes. It has been shown that in addition to the elimination-addition mechanism (EA; hetaryne intermediate), other reaction paths (anomalous addition-elimination mechanism [AEa] and “Reinecke mechanism”) are possible for nucleophilic cine-substitutions on hetaryl halides. The use of deuterated hetaryl halides has proved very valuable for the elucidation of the mechanism of nucleophilic substitutions. Even where substitution mechanisms are superimposed on one another the occurrence of a hetaryne intermediate can be detected by a technique known as the “base competition method”. A five-membered hetaryne (4,5-didehydro-1-methylimidazole) has been detected for the first time by this method with a probability that borders on certainty. Selectivity determinations have shown that the replacement of a CH group in 1,2-didehydrobenzene and in 1,2-didehydronaphthalene by an N atom distinctly increases the reactivity to bases. According to EHT (Extended Hückel Theory) calculations, the as yet hypothetical 2,3-didehydropyridine is richer in energy than 3,4-didehydropyridine, this agrees more closely with the experimental findings than the opposite result obtained from simple MO calculations. Besides cine-substitution (1,2 shift), tele-substitution (1,3-shift) has also been observed on reaction of hetaryl halides (pyridine, quinoline, and pyrimidine systems) with bases. An EA mechanism (via m-didehydrohetarenes) and an AEa mechanism are considered as alternatives for the tele-substitution.
    Additional Material: 7 Ill.
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  • 79
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    Angewandte Chemie International Edition in English 10 (1971), S. 98-104 
    ISSN: 0570-0833
    Keywords: Vinyl azides ; Azides ; Synthetic methods ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A critical survey of synthetic approaches to vinyl azides is presented, focusing especially on stereo- and regiochemical problems. The com bined procedure of azidohalogenation of olefins followed by dehydrohalogenation, leads to regiospecific and, in the case of ionic additions, also to stereospecific formation of vinyl azides. Nucleophilic substitutions by azide ions on activated olefinic halides result in β-azidovinyl ketones, esters, nitriles, etc., and proceed predominantly with retention of configuration about the C=C bond. The known synthetic methods leading to α-azidovinyl ketones and esters give rise to the thermodynamically more stable trans-vinyl azides.
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  • 80
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    Angewandte Chemie International Edition in English 10 (1971), S. 11-20 
    ISSN: 0570-0833
    Keywords: Valence isomerization ; Heterocycles ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Valence isomerization and the phenomenologically related principle of valence tautomerism, as they apply to several nitrogen-containing heterocyclic systems, are discussed herein. Attention is called first to 1H-azepines and the reluctance of such substances to isomerize to azanorcaradienes. The role of homo-1H-azepines in this context is then briefly outlined. Azocines (azacyclooctatetraenes) are seen to occupy an interesting position in the sense that pronounced shifts in the position of equilibrium (from almost entirely monocyclic to virtually completely bicyclic) occur with substitutional alterations of various types. The capability of azabullvalenes for degenerate valence isomerization is the next presented, and contrast is made with the properties of benzazabullvalenes and an azasemibullvalene derivative.
    Additional Material: 3 Ill.
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  • 81
    ISSN: 1432-0827
    Keywords: Bone ; Epiphyses ; Calcification ; Physiologic ; Phospholipids ; Phosphorus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Description / Table of Contents: Résumé Neuf polets, âgés de huit semaines, ont reçu 1 mCi de32P orthophosphate par voi intrapéritonéale. Ils ont été sacrifiés 2, 14, 38, 86 et 169 heures asprès injection. Les épiphyses des os longs ont été prélevées et séparés en cartilage au repos, cartilage en voie de prolifération, cartilage en voie de calcification et os spongieux primitif. Les lipides sont extraits: chaque tissu est déminéralisé et les lipides sont extraits à nouveau. On détermine ainsi le contenu en lipides totaux et en phospholipides, ainsi que leurs divers types et l'activité spécifique relative: Le contenu lipidique total de tous les tissus épiphysaires est de 1,35 à 4,52% en poids sec de matrice déminéralisée. La fraction phospholipipidique constitue environ la moitié des lipides. Dans les régions à contenu élevé en calcium, plus de phospholipides sont extraits après déminéralisation qu'avant. Des phospholipides neutres constituten 80–90% des phospholipides totaux dans les extraits réalisés avant déminéralisation, et seulement 48–65% dans les extraits après déminéralisation. La quantité des phospholipides, éthanolamine et sérine, est variable dans les diverses zone épiphysaires. La quantité et les types de phospholipides et leur rapport avec le degré de calcification concordent avec les résultats publiés pour les tissus de veaux. Les courbes d'activité spécifique démontrent une activité réduite au niveau de cartilage au repos et des échange très actifs en phospholipides dans les trois autres zones épiphysaires. Les divers types de phospholipides ont des activités métaboliques nettement différentes les uns par rapport aux autres. Les modes d'échanges particuliers de la phosphatidyle ethanolamine, de la phosphatidyle sérine et de la phosphatidyle inositol, au niveau du cartilage en voie de prolifération et de calcification, suggérent un rôle spécial de ces lipides dans le mécanisme de las croissance et de la calcification.
    Abstract: Zusammenfassung Neun achtwöchige Hühner erhielten intraperitoneal 1 mCi32P-Orthophosphat und wurden 2, 14, 38, 86 und 169 Std nach der Injektion getötet. Die Epiphysen der Röhrenknochen wurden seziert und ruhende, proliferierende und verkalkende Knorpel, sowie primäre Spongiosa voneinander getrennt. Die Lipide jeder Zone wurden extrahiert, jedes Gewebe wurde demineralisiert und die Lipide erneut extrahiert. Der Gehalt der Extrakte an Gesamtlipden und Phospholipiden sowie die Art der Phospholipide wurden bestimmt und die relative spezifische Aktivität: gemessen. Der Gehalt an Gesamtlipiden aller epiphysischen Gewebe betrug 1,35–4,52% des Trockengewichtes der demineralisierten Matrix. Phospholipide machten ungefähr die Hälfte der Gesamtlipide aus. In den Zonen mit hohem Calciumgehalt konnten mehr Phospholipide nach der Demineralisation als vorher extrahiert werden. Die neutralen Phospholipide entsprachen in vor der Demineralisation erhaltenen Extrakten 80–90% und in jenen nach der Demineralisation nur 48–65% der gesamten Phospholipide. Die Aethanolamin- und Serinphospholipidmengen variierten bedeutend in den verschiedenen Zonen der Epiphyse. Die Menge und die Art der Phospholipide und ihr Verhältnis in bezug auf Verkalkungsgrad waren in Einklang mit den Werten, die für das Kalb angegeben werden. Die Kurven der relativen spezifischen Aktivität zeigten ein träges metabolisches Muster im ruhenden Knorpel und einen sehr aktiven Phospholipidumsatz in den drei anderen Zonen der Epiphyse. Die verschieden gearteten Phospholipide zeigten untereinander merklich verschiedene metabolische Muster. Die speziellen Eigenschaften der Umsatzsmuster von Phosphatidyläthanolamin, Phosphatidylserin und Phosphatidylinositol in proliferierendem und verkalkendem Knorpel lassen vermuten, daß diese Lipide spezielle Funktionen im Wachstums- oder Verkalkungsprozeß ausüben.
    Notes: Abstract Nine eight-week old chicks were given32P orthophosphate, 1 mCi, intraperitoneally and killed 2, 14, 38, 86, and 169 hours after injection. Long bone epiphyses were dissected and separated into resting cartilage, proliferating cartilage, calcifying cartilages, and primary spongiosa. Lipids were extracted from each zone, each tissue was demineralized, and lipids were extracted again. The extracts were analyzed for total lipid and phospholipid content, types of phospholipids, and relative specific activity. Total lipid content of all epiphyseal tissues was 1.35 to 4.52% of the dry demineralized matrix weight. Phospholipid was about half the total. In the zones with higher calcium content more phospholipid was extracted after demineralization that before. Neutral phospholipids were 80 to 90% of the total phospholipids in predemineralization extracts and only 48 to 65% in extracts after demineralization. The amount of ethanolamine and serine phospholipids varied considerably in different epiphyseal zones. The amount and types of phospholipid and their relation to degree of calcification corroborated data reported for the calf. Relative specific activity curves revealed a sluggish metabolic pattern in resting cartilage and very active phospholipid turnover in the other three epiphyseal zones. The different types of phospholipids had markedly different metabolic patterns from each other. Special features of the turnover patterns of phosphatidyl ethanolamine, phosphatidyl serine, and phosphatidyl inositol in proliferating and calcifying cartilage suggest special roles of these lipids in the growth or calcification process.
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  • 82
    ISSN: 0570-0833
    Keywords: Tetradentate ligands ; P ligands ; Arsenic ligands ; Phosphorus ; Arsenic ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The effect of ligand shape on coordination numbers and geometry of coordination compounds has been studied using two tetradentate ligands containing phosphorus and arsenic. These tend to form five-coordinate complexes with trigonal bipyramidal structure [Fe(II), Co(I), Co(II), Rh(I), Ni(II), Pd(II), Pt(II)], but can also form six-coordinate complexes with octahedral structure [Fe(II), Ru(II), Os(II), Co(III), Rh(III), Pd(IV), Pt(IV)]. The magnetic properties and the stereochemistry of the complexes are explained by ligand field theory which predicts that, for metal ions with d6-electronic configuration, a low overall field strength should favor the formation of five-coordinate paramagnetic complexes while a high overall field strength should favor the formation of six-coordinate diamagnetic complexes. - This work provides further indication that the tendency of polydentate ligands to use all the potential donor atoms is not as pronounced as is generally believed. This is shown by the isolation of chromium(III) complexes in which the tetradentate ligands are, in fact, acting as tridentate, and by the isolation of mercury(II) complexes where only two of the four donor atoms of the polydentate ligand are actually bonded to the central metal atom.
    Additional Material: 9 Ill.
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  • 83
    ISSN: 0570-0833
    Keywords: Quinones ; Quinones ; Michael addition ; Synthetic methods ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: If catechol or other hydroquinones are dehydrogenated in the presence of a nucleophilic reagent, the latter reacts, usually by Michael addition, with the quinone formed in situ. The wide range of possible variations offered by this synthetic method is comprehensively described in the present paper. procedures are given for carrying out typical reactions.
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  • 84
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    Angewandte Chemie International Edition in English 3 (1964), S. 250-260 
    ISSN: 0570-0833
    Keywords: Unsaturated fatty acids ; Fatty acids ; Carbonyl olefination ; Synthetic methods ; Wittig reactions ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: It is shown that carbonyl olefination, i.e. the reaction of carbonyl compounds with alkylidene phosphoranes, can be sterically controlled. In some cases cis-olefins can be obtained by proper choice of the reaction conditions; trans-olefins are formed only in the presence of suitable structural factors. These cis-and trans-olefination reactions have opened new, stereo-specific routes to unsaturated and polyunsaturated fatty acids with differing positions and sequences of cis- and trans-double bonds and to ω-hydroxy and branched chain fatty acids.
    Additional Material: 2 Tab.
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  • 85
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    Angewandte Chemie International Edition in English 3 (1964), S. 333-341 
    ISSN: 0570-0833
    Keywords: Strained molecules ; Heterocycles ; Diaziridines ; Diazirines ; Oxaziranes ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Since their discovery five years ago, the diaziridines have become an extensive and easily accessible class of compounds. Hydrolysis of these compounds effects a simple synthesis of hydrazine, alkylhydrazines, and N,N′-dialkylhydrazines. They are also powerful oxidizing agents. The rigidity of the three-membered ring gives rise to a few stereoelectronic peculiarities. Investigations on the mechanism of formation of the three-membered rings led to a new synthesis of oxaziranes and to discovery of the isomeric oximes with a three-membered ring structure. The latter decompose readily to form diimide. Diazirines are cyclic isomers of the aliphatic diazo compounds and are surprisingly easy to obtain by dehydrogenation of suitable diaziridines; they are chemically much more stable than the linear isomers. Grignard reagents add onto the N=N double bond without destruction of the three-membered ring. Thermal decomposition yields carbenes.
    Additional Material: 1 Ill.
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  • 86
    ISSN: 0570-0833
    Keywords: Cyclization ; Dialdehydes ; Nitromethane ; Carbohydrates ; Polyalcohols ; Synthetic methods ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Condensation of nitromethane with suitable diadehydes in alkaline medium provides a general method of cyclization, in which the methyl group of the nitromethane is incorporated into the ring. This method leads to 5-, 6-, and 7-membered rings and is equally applicable to aliphatic, aromatic, and sugar dialdehydes. For example, glyoxal is converted into 1,4-dideoxy-1,4-dinitro-neo-inositol, and glutaraldehyde into trans-2-nitrocyclohexane-1,3-diol, while the corresponding cyclization of xylo-trihydroxyglutaraldehyde leads to deoxy-nitroinositols having the scyllo, myo-1, and muco-3 configurations.-In the case of aromatic dialdehydes, the cyclization is accompanied by elimination of water. Thus, phthalaldehyde, naphthalene-2,3-dicarboxaldehyde, and homophthalaldehyde yield, respectively, 2-nitroindenol, 2-nitrobenzindenol, and 2-nitronaphthalene. -Application of the method to sugar dialdehydes (aldehydic diglycol derivatives of monosaccharides formed by periodate oxidation) constitutes an excellent synthesis of 3-amino sugars, since 3-deoxy-3-nitropyranoses are formed smoothly on cyclization, and the corresponding 3-amino derivatives are obtained by hydrogenation. Thus, the reaction sequence: periodate oxidation → cyclization with nitromethane → hydrogenation, leads in the case of α-and β-D-pentosides to 3-amino-3-deoxy-D-and-L-pentosides, respectively, with ribo, xylo, and arabino configurations. α-D-hexosides give derivatives with gluco, manno, and galacto configurations. 3-Amino-3,6-dideoxyglucosides of the D-and L-series are obtained from 6-deoxy-D-or-L-hexosides, respectively, and 3-aminohexosans with gulo, ido, and altro configurations are obtained from 1,6-anhydro sugars. Cyclization of the dialdehydes obtained from sedoheptulose and methyl 4,6-O-ethylidene-α-D-glucoside by periodate oxidation, leads to 3-nitro and, after hydrogenation, to 3-amino derivatives of 3-deoxyheptopyranoses.
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  • 87
    ISSN: 0570-0833
    Keywords: Kinetics ; Dipolar cycloaddition ; Cycloaddition ; Heterocycles ; Reaction mechanisms ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Criteria for the mechanism of 1,3-dipolar cycloadditions which lead to 5-membered rings are provided by the stereoselectivity observed with cis-trans isomeric dipolarophiles, by the effect of solvent and substituents on the rate constants, by the activation parameters, and by orientation phenomena. A concerted addition, which can also be described in terms of molecular orbitals and in which the two new σ-bonds are formed simultaneously, although not necessarily at equal rates, offers the best explanation of the experimental facts.
    Additional Material: 2 Ill.
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  • 88
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    Angewandte Chemie International Edition in English 2 (1963), S. 24-29 
    ISSN: 0570-0833
    Keywords: 3-Aminoquinazol-4-one ; 3-Aminobenzotriazin-4-one ; Quinazolones ; Benzotriazinones ; Synthetic methods ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Among the derivatives of 3-aminoquinazol-4-one and 3-aminobenzotriazin-4-one are compounds with narcotic, sedative, analgetic, and muscle-relaxant properties. Of special interest are compounds with one or several urethane groups and those substituted in the 3-position by a morpholine moiety.
    Additional Material: 4 Tab.
    Type of Medium: Electronic Resource
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  • 89
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    Electronic Resource
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 2 (1963), S. 225-238 
    ISSN: 0570-0833
    Keywords: Pyridinium salts ; Synthetic methods ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: This review discusses syntheses leading to a new type of N-vinylpyridinium salts, to novel anionocyanines, to aminophenazines and alloxazines, as well as to (aza-) dehydroquinolizinium, acridizinium, and morphanthridizinium salts. In addition, Mannich reactions and aminoalkylations at active methylene groups of cycloimmonium salts, and their reactions with amines are treated. The possibilities offered by the “Ortoleva-King” reaction are demonstrated using numerous examples, such as a new route leading to the yohimbine skeleton.
    Type of Medium: Electronic Resource
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  • 90
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 2 (1963), S. 459-476 
    ISSN: 0570-0833
    Keywords: Aminoguanidine ; Heterocycles ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Due to its unique structure, aminoguanidine is capable of reacting as a derivative of hydrazine, guanidine or formamidine. Addition and condensation reactions yield products which can be cyclized to heterocyclic compounds. Frequently, heterocyclics are directly accessible from aminoguanidine in one stage.
    Type of Medium: Electronic Resource
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  • 91
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 2 (1963), S. 523-530 
    ISSN: 0570-0833
    Keywords: Semimetals ; Metallic structure ; Nonmetallic structure ; Antimony ; Arsenic ; Bismuth ; Phosphorus ; Tellurium ; Tin ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Measurements on semimetals have been continued. Studies of the dependence on temperature of various properties have provided details regarding the transition from the nonmetallic to the more metallic structure. A second-order transition has been found for tin at 170 °C, in which the c-axis remains unchanged, while the a-axis undergoes a small, discontinuous elongation.
    Additional Material: 13 Ill.
    Type of Medium: Electronic Resource
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  • 92
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 2 (1963), S. 565-598 
    ISSN: 0570-0833
    Keywords: Dipolar cycloaddition ; Cycloaddition ; Heterocycles ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In contrast to the very large number of special methods applicable to syntheses in the heterocyclic series, relatively few general methods are available. The 1,3-dipolar addition offers a remarkably wide range of utility in the synthesis of five-membered heterocycles. Here the “1,3-dipole”, which can only be represented by zwitterionic octet resonance structures, combines in a cycloaddition with a multiple bond system - the “dipolarophile” - to form an uncharged five-membered ring. Although numerous individual examples of this reaction were known, some even back in the nineteenth century, fruitful development of this synthetic principle has been achieved only in recent years.
    Additional Material: 4 Tab.
    Type of Medium: Electronic Resource
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  • 93
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 2 (1963), S. 309-323 
    ISSN: 0570-0833
    Keywords: s-Triazines ; Synthetic methods ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The preparation and properties of s-triazine are discussed. Nucleophilic reagents (even water) readily attack s-triazine. Thus, open-chain and heterocyclic compounds, e.g. formamidines, aminomethylene compounds, and triazole, pyridine, and pyrimidine deravatives are accessible from s-triazine. With amidines and imido ethers substituted triazines are obtained (by trans-triazination).The latter are formed via open-chain intermediates.
    Additional Material: 11 Tab.
    Type of Medium: Electronic Resource
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  • 94
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 2 (1963), S. 646-654 
    ISSN: 0570-0833
    Keywords: Polyphosphanes ; Phosphanes ; Phosphorus ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: While silicon and sulfur, which are situated to the left and to the right of phosphorus in the periodic table, from numerous chain and cyclic Si-Si and S-S-compounds with varying numbers of members, until recently the polyphosphance chemistry has been limited to the two-membered compounds diphosphane P2H4 and its derivatives. A number of results obtained in studies on polyphosphanes carried out in recent years will therefore be discussed, which, together with some more recent work by other authors, have led to an expansion of our knowledge of the prepration and properties of straight and branched-chain as well as of cyclic and polycylic -P-P-systems.
    Type of Medium: Electronic Resource
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  • 95
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 2 (1963), S. 380-393 
    ISSN: 0570-0833
    Keywords: Pyridinium salts ; Synthetic methods ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Cleavage of N-phenylpyridinium or N-vinylpyridinium salts with secondary aliphatic amines leads to aromatic amino compounds or enamines which are often unobtainable by other routes. The other fragment, glutacondialdehyde or its monoanil, gives azulenes, as shown by Ziegler and Hafner, as well as König; these compounds can also be prepared from alkylpyridinium salts with cyclopentadienylsodium (Hafner). Syntheses of labile aldehydes which are otherwise difficult to obtain and of α-ketocarboxylic acids, starting from pyridinium salts and proceeding via nitrones or α-cyanoanils, are illustrated by many new examples. Benzimidazoles, benzothiazoles, and amidines are accessible from pyridinium salts via nitrones or α-cyanoanils; cyanoanils can be transformed into quinoxalines (including xanthopterine), perimidines, etc. Furthermore, nitrosonaphthols and nitrosonaphthylamines react with pyridinium salts containing an active methylene group on the nitrogen, leading to new ring systems. Further synthetic possibilities arise from nucleophilic displacements of the pyridine in pyridinium salts by SN 2 reactions. Combination of the route via nitrones with the methods of Arndt-Eistert, Ortoleva-King, or with chloromethylation constitutes a significant enlargement of its range of application. The formation of α-cyanoanils from diazoketones permits synthesis of α-keto-β-amino acids from α-amino acids, or of phenylglyoxylic acids from benzoic acids by chain extension.
    Type of Medium: Electronic Resource
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  • 96
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 1 (1962), S. 8-21 
    ISSN: 0570-0833
    Keywords: Addition ; Immonium ions ; Isocyanides ; Amino acids ; Synthetic methods ; Alkylidene ammonium ions ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The α-addition of immonium ions and anions (OH-, SeH-, S2O3 2-, N3- NCO- NCS-, R—CO2 -, RO—CO2-) to isonitriles, accompanied by secondary reactions provides a means for the one-stage synthesis of organic nitrogen compounds starting with two to five different components. Thus, by the condensations of amines (ammonia, primary, and secondary aliphatic and aromatic amines, hydrazines) and aldehydes or ketones with isonitriles and acids, a number of α-aminocarboxylic acid amides, thioamides, selenoamides, 1,5-disubstituted retrazoles, hydantoin imides, thiohydantoin imides, α-acylamino carboxylic acid amides, oligopeptide derivatives, β-lactams, derivatives of penicillanic acid, urethanes, diacylimides, and various hydrazine derivatives, can be prepared. The reactions are easily carried out and take place under mild conditions. Yields of more than 90% are frequently encountered.
    Additional Material: 4 Tab.
    Type of Medium: Electronic Resource
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  • 97
    ISSN: 0570-0833
    Keywords: Amides ; Azolides ; Synthetic methods ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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  • 98
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 1 (1962), S. 617-621 
    ISSN: 0570-0833
    Keywords: Isocyanates ; Phosphorus ; Silicon ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Several aminoaryl esters of phosphoric and thiophosphoric acids were prepared by the reaction of phosphorus pentahalides with nitrophenols, followed by catalytic hydrogenation, or by treating aminophenols with phosphorus trihalides and oxidation to pentavalent phosphorus. These amino esters were then converted into isocyanato esters by the action of phosgene. Isocyanates of phosphonates have been synthetized on the same principle, as well as via the Arbusov reaction of halogen-substituted isocyanates with trialkyl phosphites. The reaction of silicon halides or alkylhalogenosilanes with aminophenols yielded aminoaryl esters of silicic acid or its derivatives, which could also be treated with phosgene to convert them into isocyanato esters.
    Type of Medium: Electronic Resource
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  • 99
    ISSN: 0570-0833
    Keywords: Michael addition ; Pyridinium salts ; Synthetic methods ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: By Michael addition of the active methylene groups in pyridinium salts onto suitable acceptor compounds, α-pyridones, substituted pyridines, particularly pyridinecarboxylic acids and pyridylpyridines, including the minor alkaloid of tobacco nicotelline and annelized pyridines, can be prepared by a simple procedure and generally in good yields. From the Michael adducts, polycyclic aromatic hydrocarbons, e.g. substituted fluoranthenes and “bisfluoranthenes” can be prepared; internal Michael addition leads to pyrrolinopyrdinium salts. For example, Michael addition of pyridinium salts onto quinones gives phenacyl substituted quinones, from which benzofurans and cinnolines can be readily obtained.
    Type of Medium: Electronic Resource
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  • 100
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 1 (1962), S. 652-656 
    ISSN: 0570-0833
    Keywords: β-Chloroethanephosphonic dichloride ; Phosphorus ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Ethylene, phosphorus trichloride, and oxygen react together to give β-chloroethylphosphonic dichloride in good yields. Being a bifunctional acid chloride, this compound undergoes polycondensation reactions with other, at least bifunctional, compounds affording polyesters, polyamides, epoxy resins, etc. β-Chloroethylphosphonic dichloride also may be converted into vinylphosphonic dichloride, thus serving as a starting material for the preparation of vinylphosphonic acid and its derivatives. These undergo both homopolymerization and copolymerization with compounds containing olefinic double bonds. The products are used in the field of synthetic resins, for dressing textiles, and as protective surface coatings.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
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