Transesterifications over titanosilicate molecular sieves

Titanosilicate molecular sieves (TS-1, Ti-MCM-41 and amorphous TiO2–SiO2) catalyze transesterification reactions. Acidity measurements (pyridine adsorption-IR and NH3-TPD) reveal the presence of only weak Lewis acid sites. Catalytic activity parallels the acid strength and increases in the order: TS-1 < Ti-MCM-41 < amorphous TiO2–SiO2. TS-1 efficiently catalyzes the transesterification of only linear esters (ethylacetoacetate and diethylmalonate), but fails for cyclic esters like propylene carbonate. Ti-MCM-41 and amorphous TiO2–SiO2 are superior for the latter. The catalysts could be recycled without any loss in activity/selectivity.