p-置換無水安息香酸とジメチルスルホキシドとの反応
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概要
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The reactions of <I>p</I>-substituted benzoic anhydrides with dimethyl sulf oxide (DMSO) in dioxane gave the corresponding α-benzoyloxymethylmethyl sulf ides. Results of the rate measurements indicated that this reaction followed second-order integrated equation. Hammett's ρ value was positive. The activation energy and the frequency factor were obtained in the reaction of <I>p</I>, <I>p</I>'dinitrobenzoic anhydride with DMSO. The kinetic isotope effect of this reaction with DMSO-d<SUB>6</SUB> was small (<I>k</I><SUB>H</SUB>/<I>k</I><SUB>D</SUB>=1.21 at 100.2°C) and it seemed to be a secondary one. In the reaction of mixed benzoic anhydrides, two sulfides were obtained. The yield of the sulfide with a more electron-attractive substituent was higher than that with a less electron-attractive substituent.<BR>The mechanism of this reaction is discussed, and the nucleophilic attack of the DMSO-oxygen (=S→O) on the anhydride-carbon (=C=O) appears to be the rate determining step.