Abstract
The reaction of cyclic acid anhydrides with hydrogen sulfide under pressure was investigated.
The reactivity of anhydrides at 200°C was in the following order, maleic anhydride (1) > succinic anhydride (2) > hexahydrophthalic anhydride (3) > phthalic anhydride (4) > 1, 8-naphthalic anhydride (5).
The main products obtained in this reaction were the corresponding acid thioanhydride, thiolactone, and dicarboxylic acid. (1) reacted to yield only tar-like materials containing sulfur, and (5) hardly reacted.
This reaction was promoted by such catalysts as protonic acids or Lewis acids, and the yields of acid thioanhydrides increased.
Similarly the reaction was promoted by triethylamine (TEA) and the main product was a thiolactone. This result is ascribed to the acceleration of the reduction with hydrogen sulfide by addition of TEA.
