Convenient Selective Monoacylation of 1,n-Diols Catalyzed by Ion-Exchange Resins

Article abstract of DOI:10.1021/jo00084a043

Several 1,n-diols, ranging from 1,2-ethanediol to 1,16-hexadecanediol, were selectively monoacylated by transestrification in ester/octane solvent mixtures catalyzed by strongly acidic ion-exchange resisns.This method of selective esterification is quite simple and practical.The selectivity for monoester formation and initial rates of monoester formation depended on the ester/octane ratio of the solvents.The reasons for the selectivity are as follows: (1) The sulfonic acid-type ion-exchange resins usually contain 50-80percent water, and a strongly acidic aqueous layer is formed on the surface of the resins. (2) A partition equilibrium between the aqueous layer and the aprotic ester/octane layer is setup, and diols have higher partition coefficients than the product monoesters. (3) Acylation of the alcohols occurs in the aqueous layer and/or at the interface between the aqueous and the nonaqueous liquid layer. (4) The formed monoesters move away from the aqueous layer into the aprotic layer.