Insoluble poly(akylarylphosphine)siloxanes and their application as supports for catalytic transition-metal complexes

Light induced addition of diphenylphosphine (DPP) to methylvinylcyclotetrasiloxane (MVS) yielded poly(2-diphenylphosphinoethyl) cyclotetrasiloxane (DPPS). Similar treatment of allyldiphenylphosphine (ADPP) with linear poly(methylhydrogenosiloxane)-co-hexamethyldisiloxane (PMS) led to formation of poly(3-diphenylphosphinopropyl)methylsiloxane-co-hexamethyldisiloxane (PPMS). DPPS and PPMS were condensed by acid treatment to give insoluble rubbery phosphine bearing materials P₁ and P₂, respectively. Iridium and rhodium complexes were immobilized on P₁ and P₂. The ability of a high molecular weight substrate (PMS) to migrate to active catalytic centers within support matrix was examined. The effect of varying metal: phosphine ratio and total percentage metal on the support were examined during catalysis of O-silylation of ethanol with PMS and triethoxysilane (TES).