REDUCTION OF DICARBOXYLIC-ACID ANHYDRIDE WITH 2-PROPANOL OVER HYDROUS ZIRCONIUM-OXIDE

The reduction of dicarboxylic acid anhydrides with 2-propanol proceeded efficiently over hydrous zirconium oxide to give the corresponding lactones and cyclic ethers. Secondary and primary alcohols, with the exception of methanol, are able to act as hydride donors in this reduction. The reduction proceeded as nearly second order concerning the concentration of 2-propanol and minus order concerning that of acid anhydride. These results suggest that the reduction was preferred under lower concentrations of acid anhydride and higher concentrations of 2-propanol. The selectivity of lactone or ether could be changed by the reaction temperature or the molar ratio of dicarboxylic acid anhydride to alcohol.