Kinetic Investigation of the Platinum-catalysed Hydrosilylation of Vinylsiloxanes with Hydrogensiloxanes

Article abstract of DOI:10.1002/prac.19943360306

A kinetic investigation of the platinum-catalysed hydrosilylation of monofunctional oligomeric vinylsiloxanes by monofunctional oligomeric hydrogensiloxanes was performed under stoichiometric conditions with use of quantitative 1H-NMR spectrometry.The reaction rate up to 50percent conversion can be expressed by v=k .During further hydrosilylation the kinetic changed to second order.No induction period was observed.A hydrogensiloxane with a dimethylsilyl end group gives much higher rates than a siloxane with a methylsiloxy group.The main reactions of all hydrosilylations, determined by GC-MS and 29Si-NMR, are β-additions.Less then 5percent α-products are obtained.