Kinetic Study of Hydrolysis of Thioacetazone and its Related Compounds.

概要

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The rate constant of hydrolysis (k_1) of thioacetazone and that of recombination (k_2) of its components, the aldehyde and the amine, were estimated by polarography and spectrophotometry. The relationships between the rate constant (k_1), acidity function and the concentration of buffer show that the reaction is a general acid and base catalysed reaction. The equilibrium constants K in strong and weak acid solutions are evaluated to be 8・10^<-4> and 1・10^<-5>, respectively. Thermodynamic data are given as follows : ⊿H^* 15.4kcal. /mol., ⊿S^*-18.7 cal./deg. ⊿H 3.7 kcal./mol., ⊿S-2 cal./deg. for the hydrolysis, ⊿H^* 11.7kcal./mol., ⊿S^*-16.7 cal./deg. for the recombination. The sequence of stability for acid is S-methylthioacetazone > benzaldehyde thiosemicarbazone > thioacetazone > p-acetamidobenzaldehyde semicarbazone. The rate of deacetylation of p-acetamido-benzaldehyde is as small as one hundredth that of the hydrolysis of thioacetazone.
公益社団法人日本薬学会の論文
1963-10-25