Theoretical investigation into the likely reaction mechanisms of benzyl alcohol with dimethyl carbonate over a faujasite zeolite catalyst

Abstract

Benzyl methyl ether (BME) compounds are largely synthesized by the chemical industry for use as a starting material for the synthesis of other organic compounds. In order to achieve the target of green chemistry, BME can be synthesized from benzyl alcohol and dimethyl carbonate (DMC) using a zeolite catalyst. DMC is a good methylating and carboxymethylating agent that is, in contrast to other such agents, a relatively non-toxic compound. In this study, the methylation and carboxymethylation reactions of benzyl alcohol over a 3T cluster of zeolite and a 36T extended framework was investigated by density functional theory (DFT) and the ONIOM approach, respectively. Both frameworks revealed two pathways for the methylation reaction, the first involving two transition states (TSs) and the second only a single TS. Methylation via the two-TS pathway was found to be more kinetically stable than the single-TS pathway whilst the methylation reaction is kinetically favored over the carboxymethylation reaction. The rate constants with the 36T cluster were increased 104–106 fold compared to the 3T quantum cluster.