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根据DFT理论,用量子化学的方法对B(C6F5)3催化Si—H/Si—OR缩聚反应的机理进行了研究,用29SiNMR对1,4-双(二甲基硅基)苯(BDSB)与二甲基二甲氧基硅烷、甲基乙烯基二甲氧基硅烷、二苯基二甲氧基硅烷缩聚产物的微观结构进行了表征,结合反应机理,对单体的结构与缩聚产物的微观结构的关系进行了讨论。B(C6F5)3先与Si—H形成弱加合物,然后Si—OR进攻Si—H/B(C6F5)3加合物使Si—H断裂,形成氧钅翁离子中间体,最后H-向正电中心迁移形成产物。H-迁移方向的不同将导致3种反应:缩合、交换、逆反应。烷氧基硅烷中的乙烯基、苯基可以增加烷氧基C的正电性,并使C—O键伸长,减少Si—H/Si—OR交换反应的发生,使得缩聚产物具有更为交替的结构。
According to the DFT theory, the mechanism of Si-H / Si-OR polycondensation catalyzed by B (C6F5) 3 was studied by quantum chemical method. The effects of BDSB on the With the dimethyl dimethoxysilane, methyl vinyl dimethoxy silane, the diphenyldimethoxysilane polycondensation product of the microstructure was characterized by combining the reaction mechanism of the monomer structure and the polycondensation product The relationship between microstructure was discussed. B (C6F5) 3 first forms a weak adduct with Si-H, then Si-OR attack Si-H / B (C6F5) 3 adduct to Si-H rupture to form Oxygen ion intermediates, and finally H- Migration to the positive center to form a product. H-migration of the different will lead to three kinds of reaction: condensation, exchange, reverse reaction. Alkoxysilanes in alkoxysilane, phenyl can increase the positive charge of alkoxy C, and C-O bond elongation, reducing the occurrence of Si-H / Si-OR exchange reaction, making polycondensation products have more Alternate structure.