Synthesis of Non-symmetrical Alkyl Carbonates from Alcohols and DMC over Nanocrystalline ZSM-5 Zeolite

A novel heterogeneous acid (nanocrystalline ZSM-5) catalyzed carboxymethylation of alcohols to non-symmetrical alkyl carbonates using DMC has been realized. Nanocrystalline ZSM-5 (NZSM-5) with crystal size of 20-30 nm was synthesized by hydrothermal crystallization. The synthesized NZSM-5 was verified by X-ray diffraction, Fourier transformation infrared spectroscopy and Solid state NMR. The morphology of the NZSM-5 was confirmed by Transmission electron microscopy and Scanning electron microscopy, which revealed the formation of aggregates of zeolite (100-200 nm) made by the nano-sized (20-30 nm) NZSM-5 particles packing. The physicochemical properties of NZSM-5 were measured by nitrogen adsorption and temperature programmed desorption of ammonia, which indicates the surface area of 465 m2g-1 and acidity of 0.936 mmolg-1. The present protocol provides an attractive approach to a variety of non-symmetrical alkyl carbonates in high yields. The catalyst was efficiently recycled for up to 5 consecutive cycles. This method broadens the series of possible utilization for DMC in green chemistry.