New heterogeneous catalysts for greener routes in the synthesis of fine chemicals

摘要

New strong Lewis acid SnTf-MCM-41 and SnTf-UVM-7 catalysts with unimodal and bimodal pore systems were prepared in a two-step synthesis in which the triflic acid(Tf)was incorporated to previously synthesized mesoporous tin-containing silicas.The Sn incorporation inside the pore walls was carried out through the Atrane method.The SnTf-UVM-7 catalysts were prepared by aggregating nanometric mesoporous particles defining a hierarchic textural-type additional pore system.Following these procedures,catalysts with different Si/Sn ratios-21.8 to 50.8 for SnTf-MCM-41 and 18.4 for SnTf-UVM-7-were prepared.These new materials were tested in the acylation of aromatic sulfonamides using acetic acid as the acylating agent and in the synthesis of(dl)-[alpha]-tocopherol through the condensation of 2,3,6-trimethylhydroquinone(TMHQ)with isophytol(IP).The activity data indicate that these heterogeneous catalysts are very active,corresponding to high yields in acylated compounds as 65.5% and very high selectivity to(dl)-[alpha]-tocopherol(94%,for a conversion of 98%).