Studies on the Sulfur-containing Chelating Agents. XLVI. Hydrolysis of Thio-β-diketones and Related Amides in Acetonitrile-Water Mixture

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Thioacetoacetanilide (I) was prepared through β, β-dimercaptobutyranilide by addition of H_2S to acetoacetanilide. The acid dissociation constants (pK_a) of I and thiothenoyltrifluoroacetone (II) were determined spectrophotometrically to be 6.21±0.03 and 4.38±0.09 in 50% acetonitrile, respectively. The pseudo-first order rate constant for the hydrolyses of I and II were (1.55±0.28)×10^<-2> and (2.92±0.11)×10^<-4> min^<-1 > in 50% acetonitrile, respectively. They depended on the concentration of water, but not on pH over 1-7 and 1-5,respectively. The related compounds, thiobenzoylacetanilide, thiodibenzoylmethane and benzoylthioacetone were also investigated similarly for comparison. The former was hydrolyzed but the latter two were oxidized to form the disulfides. The introduction of phenyl group instead of methyl group into the β-position seems to make the β-thiol group resistant against the hydrolysis or the oxidation.
社団法人日本薬学会の論文
1977-01-25