Transesterification of Diethyl Oxalate with Phenol over Sol-Gel MoO3/TiO2 Catalysts.

The transesterification of diethyl oxalate (DEO) with phenol to form diphenyl oxalate (DPO) has been carried out in the liquid phase over very efficient MoO₃/TiO₂ solid-acid sol-gel catalysts. A selectivity of 100 % with a remarkable maximum yield of 88 % were obtained, which opens the route to downstream phosgene-free processes for the synthesis of polycarbonates. Interpretation of the results of various acidity measurements (NH₃ and pyridine desorption, methanol oxidation as a probe reaction) allowed us to identify the catalytic sites as Lewis acid sites. [ABSTRACT FROM AUTHOR]