Dioxomolybdenum(vi) complexes as catalytic neutral esterification agents

Abstract

Esterification reactions of carboxylic acids with different alcohols in neutral nonaqueous media have been carried out in excellent yields using catalytic amounts of dioxomolybdenum(VI) complexes of the type [MoO₂L₂] (where LH = acetylacetone, salicylaldehyde, o-aminophenol, 8-hydroxyquinoline, and 2-acetyl pyridoxime). The reactions of propionic acid with primary, secondary and tertiary alcohols in the presence of catalytic amounts of MoO₂(acac)₂ result in higher yields of the esters with primary alcohols, compared to those with secondary or tertiary alcohols. The results of the esterification reactions of propionic acid with methanol and tertiary butanol in the presence of different dioxomolybdenum(VI) complexes suggest that the homogeneous catalysts are better than heterogeneous analogues.