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  • 1
    Electronic Resource
    Electronic Resource
    Automated pre-column derivatisation HPLC (1979)
    Springer
    Chromatographia 12 (1979), S. 368-370 
    Details
    ISSN: 1612-1112
    Keywords: Automation in HPLC ; Ion-pair partion chromatography ; Pre-column derivatisation ; Alkaloids
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary An automated pre-column derivatisation system is presented. As an example of its application we have chosen ion-pair partition chromatography. Ion-pairs of a mixture of some alkaloids (apoatropine, hyoscyamine, scopolamine and ergotamine) were formed with picric acid in an aqueous phase, extracted into chloroform and injectedin-situ onto a silica gel column for separation within 15 minutes. This paper shows the possibility of making an automated pre-column derivatisation system with a relative standard deviation of less than 3% per injection (n=6). The linearity check was made for hyoscyamine and ergotamine solutions in the concentration range of 80 to 200 ng respectively 240 to 720 ng per injection and found to be linear. The information obtained is of general validity and could generate more studies in this area.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02259157
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  • 2
    Electronic Resource
    Electronic Resource
    Photochemical Rearrangements and Fragmentations of Alkenes and Polyenes (1978)
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 17 (1978), S. 150-168 
    Details
    ISSN: 0570-0833
    Keywords: Photochemistry ; Rearrangement ; Fragmentation ; Alkenes ; Polyenes ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: This article presents a systematic analysis of the numerous intramolecular reactions of electronically excited alkenes categorized according to substance class and reaction type. The rearrangements and fragmentations observed in simple alkenes are usually rediscovered in non-conjugated and conjugated dienes and polyenes, where they are accompanied by reaction types such as rearrangements involving several double bonds, cyclizations, and intramolecular cycloadditions. Geometrical factors largely determine which reaction of a series of energetically feasible competing processes actually takes place. The industrial syntheses of vitamin D utilize many of the reaction types to be discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/anie.197801501
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  • 3
    Electronic Resource
    Electronic Resource
    Vinamidines and Vinamidinium Salts - Examples of Stabilized Push-Pull Alkenes (1976)
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 15 (1976), S. 459-468 
    Details
    ISSN: 0570-0833
    Keywords: Vinamidines ; Donor-acceptor systems ; Alkenes ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The name vinamidines has been proposed for 1,5-diazapentadienes: these compounds can be regarded as vinylogous amidines and at the same time as push-pull substituted (and thereby stabilized) alkenes. Vinamidine and vinamidinium structural elements may also form part of a ring system. Characteristic of this class of compounds are their reactivity toward electrophiles (at Cβ) and nucleophiles (Cα) and their regenerative character, i.e. their tendency to undergo substitution instead of addition reactions. Reactions of vinamidinium salts with nucleophiles are of special preparative value: they lead e.g. to pyrazoles, oxazoles, pyrimidines, diazepines, quinolines, and quinolizines.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/anie.197604591
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  • 4
    Electronic Resource
    Electronic Resource
    Oxidative Condensation of Quaternary Phenolic BasesBased on lectures delivered at the International Symposium on Organic Chemistry held by the Societé Chimique de Belgique in Brussels, June 15th, 1962, the XIXth IUPAC Congress in London, July 11th, 1963, a Gordon Research Conference in New Hampton, August 2nd, 1963, and at several American universities and research institutes.Dedicated to Prof Dr. H. Brockmann on the occasion of his 60th birthday (1964)
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 3 (1964), S. 192-200 
    Details
    ISSN: 0570-0833
    Keywords: Phenolic bases ; Alkaloids ; Condensation ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Provided they contain quaternary nitrogen, simple phenolic bases can undergo oxidative condensation under conditions similar to those of biogenesis to form alkaloids of the isoquinoline series with good yields. By means of such oxidative condensations, more than sixty alkaloids of various structural types have become more easily obtainable. Of the numerous possible condensations of the intermediate mesomeric radicals only those which lead to naturally occurring alkaloids give good yields and few by-products. The results suggest that oxidative condensations of quaternary bases are also involved in the biosynthesis of alkaloids in the plant cell.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/anie.196401921
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  • 5
    Electronic Resource
    Electronic Resource
    Polar Addition of Hydrogen Halides onto OlefinsThis work was supported by a grant from the National Science Foundation. (1964)
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 3 (1964), S. 245-249 
    Details
    ISSN: 0570-0833
    Keywords: Addition ; Alkenes ; Electrophilic reactions ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Various structures have been proposed for the intermediates of electrophilic additions onto olefins; these include halonium ions, classical carbonium ions, π-complexes (i.e. nonclassical carbonium ions), and π-complexes with back-coordination. It is shown here that it is impossible to use any one of these entities alone to explain all such electrophilic additions; the electrophile itself determines the nature of the transition state formed. Polar addition of hydrogen halides onto olefins appears to proceed via a classical carbonium ion which does not occur as the free ion but as an undissociated ion pair. Various other mechanisms have been excluded by studies reported here of the stereochemical course of such additions.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/anie.196402451
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  • 6
    Electronic Resource
    Electronic Resource
    The Biosynthesis of Alkaloids IIPart I of this review appeared in Angew. Chem. Internet. Edit. 2, 341 (1963). (1963)
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 2 (1963), S. 441-458 
    Details
    ISSN: 0570-0833
    Keywords: Biosynthesis ; Alkaloids ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/anie.196304411
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  • 7
    Electronic Resource
    Electronic Resource
    Type and Extent of Isomerization of Straight-Chain Mono-olefins during the Koch Carboxylic Acid SynthesisReported in part at the meeting of the Gesellschaft Deutscher Chemiker, Aachen 1961; Angew. Chem. 73, 767 (1961). (1963)
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 2 (1963), S. 719-722 
    Details
    ISSN: 0570-0833
    Keywords: Koch carboxylic acid synthesis ; Carboxylic acids ; Alkenes ; Isomerization ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: When straight-chain mono-olefins, from pentene to decene, are subjected to the Koch carboxylic acid synthesis by the addition of CO and H2O or CH3OH in the presence of strongly acidic catalysts, not only the expected secondary acids, but also mixtures of a specific type of tertiary acids or their methyl esters are formed. When the catalysts contain boron trifluoride, the secondary acids are formed in ratios of isomers which are, within the scope of this investigation, independent of the experimental conditions and which agree well with the values calculated from the isomer equilibria of the corresponding n-olefins. Using concentrated sulfuric acid as catalyst, a larger proportion of tertiary acids is obtained than with BF3-catalysis, and amongst the secondary acids, those isomers predominate in which the COOH group is situated near the centre of the molecule.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/anie.196307191
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  • 8
    Electronic Resource
    Electronic Resource
    The Biogenesis of Ergot AlkaloidsDedicated to Professor Hans von Euler on the occasion of his 90th birthday (1963)
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 2 (1963), S. 243-247 
    Details
    ISSN: 0570-0833
    Keywords: Ergot alkaloids ; Alkaloids ; Biosynthesis ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In this article the biogenesis of the ergoline ring in lysergic acid derivatives and the clavines is discussed. T·yptophan and mevalonic acid are the precursors. The N-methyl group is supplied by formate or methionine. Concepts and results dealing with the manner in which the compounds are formed are discussed. Finally, the known biogenetic relationships among the ergot alkaloids are discussed in connection with their biogenesis.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/anie.196302431
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  • 9
    Electronic Resource
    Electronic Resource
    Emulsion Polymerization of Vinyl Monomers under the Influence of Ionizing Radiation (1963)
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 2 (1963), S. 295-308 
    Details
    ISSN: 0570-0833
    Keywords: Emulsion polymerization ; Polymerization ; Polymerization ; Alkenes ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Ionizing radiation induces the polymerization of some vinyl monomers in aqueous emulsion with high radiation yields. With identical emulsion compositions, the kinetics of this reaction and the kinetics of emulsion polymerization induced by water-soluble initiators are very similar. The rate of reaction in emulsion polymerization is about one hundred times greater than in bulk polymerization. The initiation of emulsion polymerization by means of ionizing radiation permits uniform “illumination” of the reacting volume, as well as almost any desired variation in the frequency of initiation during the reaction. The sharp decrease in the overall rate of reaction when initiation is interrupted during emulsion polymerization of styrene induced by γ-rays contradicts the earlier concept of sharply separated reaction zones.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/anie.196302951
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  • 10
    Electronic Resource
    Electronic Resource
    The Biosynthesis of Alkaloids IPart II of this review will appear in a subsequent issue of this journal.Dedicated to Professor Dr. Adolf Butenandt on the occasion of his 60th birthday (1963)
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 2 (1963), S. 341-357 
    Details
    ISSN: 0570-0833
    Keywords: Biosynthesis ; Alkaloids ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/anie.196303411
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  • 11
    Electronic Resource
    Electronic Resource
    Reactions of Olefins with the Titanium-Carbon BondDedicated to Prof. Dr. Karl Ziegler on the occasion of his 65th birthday (1963)
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 2 (1963), S. 704-714 
    Details
    ISSN: 0570-0833
    Keywords: Titanium ; Alkenes ; Polymerization ; Titanium ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: At low temperatures, ethylene and α-olefins (Δ1-olefins or 1-alkenes) are rapidly converted into oligomrs by the two-component organometallic catalyst CH3TiCl3·CH3AlCl2. To achieve smooth oligomerizations, aromatic or chlorinated hydrocarbons must be used as solvents. Although the activity of the titanium-carbon bond is enhanced by the aluminum component of the catalyst, the aluminum and its methyl group do not participate in the reaction proper; the latter proceeds exclusively at the titanium-carbon bond. The reaction will olefins can be used as an analytical method for the quantitative determination of the titanium-carbon bond in admixture with the organoaluminum component. It is thus possible to follow the reaction leading to formation of the catalyst from titanium tertrachloride, as well as the processes occurring at the titanium-carbon bond during the oligomerization of olefins. All the observations indicate that the catalyst possesses an ionic structure which is determined by the solvent. It is shown that the initial reaction step probably involves formation of a complex between the olefin and the alkyltitanium cation. The reaction scheme proposed is based on organometallic reactions which are characterized by carbanion and hydride transfers within the olefin-cation complex. This mechanism, which is unusual for Ziegler catalysts, is due to the predominance of hydride transfers.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/anie.196307041
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  • 12
    Electronic Resource
    Electronic Resource
    The Oxidation of Olefins with Palladium Chloride Catalysts (1962)
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 1 (1962), S. 80-88 
    Details
    ISSN: 0570-0833
    Keywords: Oxidation ; Palladium ; Catalysis ; Alkenes ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The oxidation of olefins to carbonyl compounds with palladium compounds, especially the oxidation of ethylene to acetaldehyde, is at present carried out on a technical scale. The reaction takes place via a palladium-olefin complex, the formation of which is inhibited by halide ions. Hydrolysis to the carbonyl compound is inhibited by hydrogen ions. The knowledge gained by studying the reaction of olefins with pure solutions of palladium salts allows important conclusions to be drawn concerning the action of technical catalyst solutions containing copper and palladium chloride.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/anie.196200801
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