Chapter 1.6 Solid-phase hydrosilylation reactions with participation of modified silica surface

Abstract

A substantial experience has been gained in the field of the formation of modified silicas with attached silicon hydride and olefin groups. Matrices with attached silicon hydride groups can be produced as a result hydrolysis and polycondensation of trichloro- and triethoxysilane (including on silica surface), during chemical modification of silica with various organosilanes containing Si-H bonds or by means of the molecular layering method. The hydridesilicas can be produced by the reaction between inorganic hydrides and ≡SiCl groups of the chlorinated silica surface or as a result of the thermal destruction of methoxysilica. Matrices with attached silicon hydride groups can be successfully applied for carrying out processes of catalytic solid-phase hydrosilylation of simple terminal and functional olefins. Reactions of catalytic hydrosilylation proceed also with participation of attached olefin groups and hydrosilanes in a gaseous or liquid phase. The attachment of one of the participants of the hydrosilylation process to solid surface provides more convenient and favorable standpoints and approaches to researches into reaction mechanism. The experimental data give evidence that solid-phase catalytic hydrosilylation reactions involve the formation of intermediate complexes containing both of the reagents and the Speier catalyst. The possibility has been also established of effecting a non-catalytic reaction of solid-phase hydrosilylation of olefins at high pressures and temperatures. The modifying coatings obtained using solid-phase hydrosilylation reactions have a rather high hydrolytic stability and reproducible properties. This allows it to regard the reaction of solid-phase hydrosilylation as to the basis for one of promising methods of producing surface chemical compounds with Si-C bonds.