关键词: 氧化硅, 纳米相材料, 生育酚, 氢醌, 溶胶-凝胶法

The 13% Nafion/SiO——2 nanocomposite with high surface area was prepared by entrapping Nafion resin nanoparticles in a porous silica (viz. an in situ sol-gel method) and used as a catalyst for the synthesis of α-tocopherol by the Friedel-Crafts alkylation- condensation reaction of trimethylhydroquinone and isophytol. The catalytic results were compared with those obtained over Nafion NR50 resin catalyst. Due to the increased accessibility to the reactants of Nafion resin-based acid sites, the nanocomposite showed remarkbly enhanced activity for ct-tocopherol synthesis (yield > 90%) in nonpolar toluene and n-heptane solvents. The activity per unit weight of Nafion resin in toluene solvent was found to be 10 times higher in the nanocomposite than in Nafion NR50 resin. The nanocomposite catalyst proved to be recoverable from the reaction, but a gradual loss of the catalytic activity was observed with increasing the recycle number.

Key words: SILICON OXIDE, NANOPHASE MATERIALS, tocopherol, HYDROQUINONE, SOL-GEL PROCESS