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  • 1
    ISSN: 0894-3230
    Schlagwort(e): Cyclic N-substituted sulfonamides ; 1,2,5-thiadiazole 1,1-dioxide derivatives ; hydrolysis ; kinetics ; Chemistry ; Theoretical, Physical and Computational Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: The hydrolysis reactions of 4-amino-2-phenethyl- and 4-amino-2-cyclohexyl-2,3-dihydro-3-oxo-1,2,5-thiadiazole 1,1-dioxide (Ia and Ib) were investigated in the range 24-73 °C in buffered aqueous solutions. The observed rate constants (kobs) are independent of pH in the range ca 1-4 pH, but increase with increase in pH above ca 4. A linear log kobs vs pH profile with unit slope is observed from pH ca 4 up to the highest experimental pH (ca 10). The products are the corresponding new compounds: 2-amino-2-[(N-substituted-sulfamoyl)imino]acetic acid salts. The C=N bond of these compounds hydrolyses further, in a slow reaction, to the sulfamide and oxalic acid derivatives. The substrates decompose to the final products without accumulation of the acetic acid derivatives under these experimental conditions. A mechanism is proposed. Rate constants and activation parameters are given for the first reaction step. Owing to steric effects, the reaction rate is higher for the N-phenethyl-substituted derivative than for the 2-cyclohexyl-substituted derivative. © 1998 John Wiley & Sons, Ltd.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 2
    Digitale Medien
    Digitale Medien
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 11 (1998), S. 91-100 
    ISSN: 0894-3230
    Schlagwort(e): 1,2,5-thiadiazole ; 1,1-dioxide derivatives ; single-crystal x-ray diffraction ; ab initio MO calculations ; structure ; conformation ; reactivity ; Chemistry ; Theoretical, Physical and Computational Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: Single-crystal x-ray diffraction studies are reported for 3,4-dimethyl (I), 3-methyl-4-phenyl (II) and 3,4-diphenyl (III) derivatives of 1,2,5-thiadiazole 1,1-dioxide. Ab initio MO calculations on the electronic structure, conformation and reactivity of I, II and III are also reported and compared with the x-ray results. The structural data are related to previous kinetic and electrochemical experimental results on these compounds. © 1998 John Wiley & Sons, Ltd.
    Zusätzliches Material: 11 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 3
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 23 (1991), S. 197-202 
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: We have performed a product and kinetic study of the hydrolysis of 3,4-diphenyl-1,2,5-thiadiazole-1,1-dioxide in aqueous solution. Benzil and sulfamide are the only products of hydrolysis and are formed in equimolar yields.The kinetic results indicate that a first order law is followed up to 90% conversion. The observed rate constant is independent of substrate concentration.Ionic strength and buffer concentration do not affect the rate constant, but the reaction is acid-base catalyzed. The rate-pH profile has been determined and a mechanism that fits the experimental data satisfactorily is proposed. Corresponding rate constants and equilibrium constants for the protonation of the substrate are reported.
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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