CaO Catalyzed Transesterification of Ethyl 10-Undecenoate as a Model Reaction for Efficient Conversion of Plant Oils and Their Application to Depolymerization of Aliphatic Polyesters

Transesterification of ethyl 10-undecenoate (derived from castor oil) with cyclohexanemethanol over a CaO catalyst (prebaked at 300 °C) gave undec-10-enoate exclusively (yield 92%, selectivity 95–98%) at 100 °C, and the activity increased at 120 °C with maintaining the high selectivity (97–98%). The transesterification with other alcohols, especially primary alcohols (2-ethyl-1-butanol, 1-hexanol, 3-buten-1-ol, and 10-undecen-1-ol), afforded the corresponding esters with high selectivity, indicating the possibility for application of efficient conversion of plant oils to various fine chemicals including the monomer for the synthesis of polyesters. Efficient acid-, base-free depolymerization of aliphatic polyesters, poly(ethylene adipate) and poly(butylene adipate), has been demonstrated in this catalysis by transesterification with ethanol and cyclohexanemethanol, affording corresponding adipates and ethylene glycol or butylene glycol exclusively: the reusability of a CaO catalyst has also been demonstrated.