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  • 1980-1984  (3)
  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Journal of thermal analysis and calorimetry 28 (1983), S. 227-236 
    ISSN: 1572-8943
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Es wurde versucht, Komplexe von Uranylacetat undN-phenylthioharnstoff in fester Phase durch Erhitzen verschiedener stöchiometrischer Gemische der Reaktanten direkt in einer DSC- und einer TA-Apparatur herzustellen. Sowohl die DSC- als auch die TG-Ergebnisse deuten darauf hin, dass nur das 1∶1-Addukt gebildet wird, und zwar unabhängig von den molaren Mischungsverhältnissen der Reaktanten. Übereinstimmend mit IR-Daten scheint die Reaktion nur bei einem grossen Überschuss anN-Phenylthioharnstoff vollständig zu verlaufen.
    Abstract: Резюме Предприняты попытки твердотельных синте зов комплексов уранилац етата с N-фенилтиомочевиной н агреванием их непоср едственно в приборах ДСК и ТА. Уста новлено, что независимо от мол ярного соотношения в зятых реагентов, всегда пол учали аддукт состава 1:1. Согласно дан ным ИК спектроскопии, реакция протекает полностью только в присутствии значит ельного избытка N-фенилтиомочевины.
    Notes: Abstract The solid-state syntheses of complexes of uranyl acetate dihydrate andN-phenylthiourea have been attempted by heating various stoichiometric mixtures of the reactants directly in a DSC and in a TA apparatus. Both the DSC and the TG results indicate that only the 1∶1 adduct is formed, independently of the molar ratios of the reactants. It appears that the reaction is complete only with a large excess ofN-phenylthiourea, in agreement with IR data.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 0030-4921
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The lanthanide shift reagent (LSR)/1H NMR study of some 7-chloro-5-phenyl-2,3-dihydro-1 H-1, 4-benzodiazepines shows that these compounds exist in CDCI3 solution as two pseudo-boat conformers, rapidly interconverting at room temperature. Computer simulated lanthanide induced shifts (LIS) are consistent with LSR complexation by the imine nitrogen atom. The lanthanide shifts the conformational equilibrium towards conformer (a), with a pseudoequatorial 1-substituent: this effect may be the result of the greater basicity of 4-N when the 1-N lone pair is pseudoaxially directed, thus permitting an extended electron delocalization from 1- to 4-N through the fused benzene ring. The detection of H-9/1-Me through space spin-spin coupling in medazepam (7-chloro-1-methyl-5-phenyl-2,3-dihydro-1H-1,4-benzodiazepine) supports the observed higher availability of conformer (a) to LSR. A LIS computer calculation to predict the population ratio results in reasonable agreement with the conformational changes based on the response of 3J(HH) to lanthanide addition. The electronic and steric effects which determine the greater stability of conformer (a) may be effective in the drug-receptor interaction.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 0030-4921
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The conformational analysis of biologically active lofendazam (7-chloro-5-phenyl-1,3,4,5-tetrahydro-2H-1,5-benzodiazepin-2-one) is carried out by means of lanthanide shift reagent assisted 1H NMR spectroscopy: the lanthanide induced shift computer simulation suggests that in deuteriochloroform the heterocyclic ring of lofendazam assumes a cycloheptene-like chair conformation, where 1-N moves away from trigonal stereochemistry to a very flattened pyramidal structure. At room temperature the conformational equilibrium is markedly shifted (85%) towards the conformer showing pseudoaxial H-1 and 5-Ph. The remarkable influence of steric requirements in controlling conformation, and the importance of 3- and/or 4-methyl groups in hindering the ring inversion at room temperature, have been verified by conformational analysis of suitable analogous 1,3,4,5-tetraydro-2H-1,5-benzodiazepin-2-ones.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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