Aminoorganosiloxane-silicate-supported rhodium complexes as catalysts for hydrosilylation of alkenes and vinylsilanes

Abstract

Aminoorganosiloxane macromolecules were synthesized by hydrolysis of diorganodi(chloro,ethoxy)silanes followed by their condensation and grafting onto chrysotile asbestos in acidic (HCl, CH 3COOH) medium. The process was accompanied by considerable increases in surface area, pore volume and pore area of the organosiloxy derivatives of chrysotile. [RhCl(c-C 8H 14) 2] 2 precursor immobilized on such supports was tested in the hydro-silylation of 1-alkenes (1-hexene, 1-octene, 1-octadecene) and vinyltri-ethoxysilane by triethoxysilane, giving high yields of the adducts. Stability tests for recycling of the supported catalysts indicate leaching of the rhodium complexes (more than 60% loss in all cases) and non-proportional loss in the catalytic activity after their six-fold use in the hydrosilylation of 1-hexene, whereas no change in the yield of bis(silyl)ethanes was observed under the same recycling conditions.