One-Step Alkoxylation of Anhydride to Synthesize Glycol Di-Ester In High Yield

Di-ester used to be synthesized in a two-step process with acetic acid or anhydride as starting material. The disadvantages of the traditional route include low yield of di-ester, some undesirable by-products which would increase separation load, and lots of waste acid solution. This paper reports a novel one-step synthesis of di-ester catalyzed by Mg-Al composite oxide, and achieved by alkoxylation of acetic anhydride with ethylene oxide or propylene oxide, respectively. The one-step process is a green chemistry approach with excellent atomic economy since neither solvent is needed nor lots of by-products are produced. More than 95% yield of the di-ester with high product selectivity(>99%) was obtained when the one-step reaction catalyzed by 1% Mg-Al composite oxide was performed in an autoclave at a molar ratio of anhydride : epoxide=1:1 at 160 ^oC for 1 h.