One-step solvent-free synthesis of cyclic carbonates by oxidative carboxylation of styrenes over a recyclable Ti-containing catalyst

A mesoporous titanium-silicate prepared by evaporation-induced self-assembly is an efficient heterogeneous catalyst for the one-step oxidative carboxylation of styrenes with tert-butyl hydroperoxide and carbon dioxide in the presence of tetrabutylammonium bromide as cocatalyst under mild solvent-free conditions (50-70°C, 8bar CO ₂ ). The selectivity to cyclic carbonates reaches 69-70% at 92-98.5% substrate conversion. The catalyst can be easily recovered by filtration and reused several times without a significant deterioration of the catalytic performance. The volume yield of SC as high as 1.1kg/L could be achieved after seven reuses.