PtO ₂ as a "self-dosing" hydrosilylation catalyst

The reaction behavior of PtO ₂ in the hydrosilylation of n-octene with heptamethyltrisiloxane was examined. PtO ₂ proved to be a highly active and selective hydrosilylation catalyst precursor reaching turn-over frequencies in the order of magnitude of 10 ⁵ h ^-1. In contrast to usual homogeneous catalysts PtO ₂ dissolves only to a small degree after reaction with silane. The un-reacted solid catalyst could be easily separated from the reaction mixture by simple decantation or filtration and could be used for subsequent runs. The observation of an induction period in every cycle indicates that the active species is formed in situ before the reaction can take place and new material has to dissolve for each run. The active species is formed by reduction of PtO ₂ with the silane and is soluble in the reaction mixture. The solubility behavior together with the high activity allows a "self-dosing" of the catalyst - leading to little waste of precious metal in contrast to other "homogeneous" (i.e. better soluble) Pt-based catalysts.