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  • 1
    ISSN: 1572-879X
    Keywords: glutamic acid specific endopeptidase (BL-GSE) ; esterification ; transesterification ; peptide synthesis ; sweetener aspartam analogues
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Esterification and transesterification reactions are carried out in water miscible organic solvents by using a new glutamic acid specific endopeptidase, isolated from Bacillus lichenifonnis. Sweetener aspartam analogues syntheses are also described.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1979 (1979), S. 639-649 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Chemistry of 1,2,4-Triazepines, XIV. - Condensations of β-Dicarbonyl Compounds with 1,2-Diaminoimidazoles
    Additional Material: 3 Tab.
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  • 3
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 12 (1977), S. 638-643 
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: The mass spectra of several 4-amino 1,2,4-triazoles with an amino, methylamino, mercapto or methylmercapto group in position 5 are reported and analysed. Five different fragmentation pathways of the molecular ion are observed in the heterocylic ring but the amino group in position 4 also involves some other specific cleavages.
    Notes: Les spectres de masse d'un certain nombre d'amino-4 triazoles -1,2,4 porteurs d'un substituant amino, méthylamino, mercapto ou méthylmercapto en position 5 sont décrits et analysés. Cinq processus de fragmentation du cycle triazole, liés à la nature du groupement fonctionnel en position 5, sont mis en évidence; l'un d'eux, identifié dans tous less cas, résulte de la rupture des liaisons N-2—C-2 et N-4—C-5.D'autres dégradation sont également observées à partir du groupment amino en position 4.
    Additional Material: 1 Tab.
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  • 4
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 11 (1976), S. 1002-1017 
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: The mass spectra of 49 1,2,4-triazines with oxo, thioxo, methoxy and methylmercapto groups in the 3 and 5 positions are reported and analysed. Five distinct patterns have been observed upon electron impact but an initial loss of N2 has not been identified. A tautomeric equilibrium has been shown to occur in the vapour phase from some fragmentation pathways.
    Notes: Les spectres de masse de 49 triazines-1,2,4 différemment substituées en position 6, possédant les groupes oxo, thioxo, méthylmercapto en position 3 et 5 et de leurs dérivés N-méthylés sont décrits. Cinq processus de fragementation du cycle traizine, liés á la structure et notamment á la nature du groupement fonctionnel en position 5 sont mis en évidence. L'un d'eux, engageant les ruptures des liaisons N-1—N-2 et C-5—C-6, est identifié dans tous les cas. Les pertes d'azote et de monoxyde de carbone ne sont pas observées. Pour certains composés la participation á l'équilibre, á l'état vapeur, de certaines formes tautoméres a été discutée.
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  • 5
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 12 (1977), S. 136-144 
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: The mass spectra of 21 1,4-pyrazolo[3,4-b]diazepines are reported and analysed. Each of the five structures of the diazepine ring present is characterized by a particular group of fragmentations; among them one is common to all the compounds under study: the cleavage of C-5—C-6 and C-7—N-8 bonds leading to pyrazoloimidazoles ions.
    Notes: Les spectres de masse de 21 pyrazolo[3,4-b]diazépines-1,4 dans lesquelles le cycle diazépine peut présenter cinq structures différentes, sont décrits et analysis. Chaque structure a été caractérisée par un ensemble original de ruptures. Parmi celles-ci un mode de fragmentation commun à tous les composés étudiés a été identifié: il s'agit de la rupture des liaisons C-5—C-6 et C-7—N-8 avec formation d'ions pyrazoloimidazoles.
    Additional Material: 1 Tab.
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  • 6
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 13 (1978), S. 74-80 
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: The mass spectra of several 5(3),1′- and 4,4′-bitriazoles are described. The main fragmentation pathways have been determined and their use in structure determinations of isomeric compounds is demonstrated. The triazolyl group in the 4 position also shows some other specific cleavages.
    Notes: Les spectres de masse d'un certain nombre de bitriazoles-5(3),1′ et bitriazoles-4,4′ sont décrits: les principales fragmentations sont données et leur utilité à la détermination des structures de composés isomères est montrée. Des dégradations spécifiques sont également observées à partir du groupement triazolyle en position 4.
    Additional Material: 1 Tab.
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  • 7
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 13 (1978), S. 344-352 
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: The mass spectra of 1,2,4-imidazo[1,5-b]triazepinones and imidazo[4,5-b]pyridinones, formed by condensation of diaminoimidazoles with β-dicarbonyl compounds, are reported and analysed. The main fragmentation pathways have been determined and the utility is shown in structure determinations of isomeric compounds.
    Notes: Les spectres de masse des deux séries d'imidazo[1,5-b]triazépinones-1,2,4 et d'imidazo[4,5-b]pyridinones, obtenues par condensation de diamino-1,5 imidazoles avec un dérivé β-dicarbonylé, sont décrits et analysés. Les principales fragmentations sont données et leur utilité à la détermination de structures des composés isomères est montrée.
    Additional Material: 1 Tab.
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  • 8
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 14 (1979), S. 369-378 
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: The mass spectra of several 4-amino-1,2,4-triazole-5-ones with different groups in position 1 have been recorded and show new skeletal rearrangements and hydrogen migrations. The comparison of the ‘normal’ and mass analysed ion kinetic energy spectra obtained by the ‘simili MIKE’ technique permits the determination of the molecular ion and fragment ion structures and also the mechanism of formation of these ions. These results show that the molecular ion of the N-1 unsubstituted 4-amino-1,2,4-triazole-5-ones exists in the gas phase in two tautomeric forms.
    Notes: Les spectres de masse d'un certain nombre d'amino-4 triazole-1,2,4 ones-5 différemment substituées en position 1 sont rapportés; ils mettent en évidence de nouveaux réarrangements et des migrations d'hydrogène. La comparaison des spectres normaux et des spectres d'énergie cinétique obtenus selon la technique simili MIKE a permis de déterminerla structure des ions moléculaires et des ions fragments et de décrirela formation de ces derniers. Ces résultats montrent que ľion moléculaire des amino-4 triazolones-5 non substituées en position 1 existe probablement en phase gazeuse sous deux formes tautomères (N-1-H et OH).
    Additional Material: 4 Tab.
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  • 9
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: The mass spectra of several pyrido [2,3-b] and [3,4-b], pyrimido [4,5-b], pyrazolo [3,4-b] diazepinones-1,4 and as-triazino [4,3-b], s-triazolo [4,3-b]triazepinones-1,2,4 are reported and analysed. Five different fragmentation pathways of the molecular ion are generally observed, but the main one is an initial loss of CH2CO which gives rise to 2-methylazabenzimidazole or 2-methyl azabenzotriazole ions. The behaviour of triazolotriazepines which have two further fragmentation pathways is described.
    Notes: Les spectres de masse des pyrido[2,3-b], pyrimido[3,4-b], pyrimido [4,5-b], pyrazolo[3,4-b]- diazépinones-1,4 et des as-triazino[4,3-b] et s-triazolo[4,3-b]triazépinones-1,2,4 sont décrits et analysés. Cinq processus de fragmentation de l'ion moléculaire sont le plus souvent identifiés, le mode principal d déradation étant l'expulsion d'une moléule de cétène avec formation des ions méthyl-2 azabenzimidazoles ou méthyl-2 azabenzotriazoles. Le comprotement particulier des triazolotriazépines, présentant deux antres types de rupture, est mis en évidence.
    Additional Material: 3 Ill.
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  • 10
    ISSN: 1434-193X
    Keywords: Amino acids ; coupling ; N-Substituted amide ; Cyclizations ; Cyclic dipeptides ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---A short synthesis of new, functionalized seven-membered ring cyclic dipeptides is described. After the coupling of N-protected β-amino acids to N-substituted α-amino tert-butyl esters, the protective groups of the terminal functions were removed and the cyclization took place diastereoselectively in the presence of the coupling agent BOP. Amide substitution was found to be effective in promoting the cyclization of linear dipeptides.
    Additional Material: 1 Ill.
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