纳米二氧化硅催化剂催化Michael加成反应

脱水活化后的纳米二氧化硅颗粒能有效催化Michael加成反应,研究了不同温度及六甲基二硅氮烷(HMDS)处理改变二氧化硅表面性质后催化剂的催化性能改变。结果表明,随着热处理温度的升高,二氧化硅催化活性降低;HMDS能够覆盖其表面的单独硅羟基,从而降低二氧化硅催化活性。研究表明,二氧化硅表面的硅羟基是催化活性中心,催化活性与硅羟基浓度相关。不同溶剂对反应活性影响明显,DMF为反应的最佳溶剂,反应收率最高可达71%。

Nano-Silica Catalyst for Michael Addition Reaction

Nano- silica activated by removing the surface water can catalyze Michael addition reaction effectively. After changing its surface properties by thermal and hexamethyldisilazane （HMDS） treatments, the performance of the catalyst for the reaction was investigated. The results show that catalytic activity is reduced as treatment temperature rises. I-IMDS can cover isolated silanols, which leads a decrease of catalytic,activity. It is suggested that the surface silanols are catalytic active center. The catalytic activity is closely related to the silanol concentration. It was also found that solvent has great influence on the reactivity. DMF is the optimum solvent for the reaction and a yield of up to 71% can be achieved.