Synthesis of dibenzyl carbonate: towards a sustainable catalytic approach

Abstract

At 90 °C, in the presence of CsF/α-Al₂O₃ or [P_8,8,8,1][H₃COCO₂] as catalysts, a straightforward protocol was set up for the synthesis of dibenzyl carbonate (DBnC) via the transesterification of dimethyl carbonate (DMC) with an excess of benzyl alcohol. The two catalysts were used in amounts as low as 1% mol (with respect to the limiting reagent DMC). Best results were achieved with CsF/α-Al₂O₃ that allowed a simpler and reproducible isolation of DBnC in yields up to 70%. Moreover, both the catalyst and the excess BnOH were recovered and could be recycled. The evaluation of mass index (MI) and cost index for the investigated procedure confirmed the economic sustainability and the choice of a rational mass flow throughout the reaction: the method was in the top 7 among 21 protocols selected as the best available options for the synthesis of DBnC.