Studies on the carboxymethylation and methylation of bisphenol A with dimethyl carbonate over TiO2/SBA-15

Carboxymethylated species were selectively synthesized from dimethyl carbonate (DMC) and bisphenol A (BPA) over TiO2/SBA-15. On the basis of catalyst characterization by means of XRD, FT-IR, HPLC and GC-MS, the relations between catalytic performance and catalyst properties were discussed. Si-O-Ti was active sites for reaction, and the interaction mode between Ti-O-Si and DMC was main factor to determine carboxymethylation and methylation. When DMC was attacked by Ti-O-Si on two oxygen atoms of CH3-O moiety, BPA attacked carbonyl carbon to form carboxymethylated products. If the interaction occurs through the oxygen of C=O moiety, BPA attacked methyl carbon to form methylated products. Chemisorbed H2O over TiO2/SBA-15 made DMC to act as methylating agent. After chemisorbed H2O was removed, carboxymethylated species of two-methylcarbonate-ended-BPA (DmC(1)) and one-methylcarbonate-ended-BPA (MmC(1)) were selectively synthesized. (C) 2009 Elsevier B.V. All rights reserved.