Recyclable and Convenient-to-Handle Pt/Ethylene Glycol Catalytic System – an Approach to Sustainable Hydrosilylation

This study presents a highly efficient and simple recyclable catalytic system for heterophase hydrosilylation. This catalytic system consisting of a commercially available platinum precatalyst, namely K2PtCl4, and a cheap green solvent, namely ethylene glycol (EG), is easily prepared by dissolving K2PtCl4 in EG without employing ligands, additives, or an inert atmosphere, at r.t. The suggested method allows up to 45 recycles with quantitative conversion under air at r.t. to be performed. The high reaction rate (from 2 to 20 min per cycle) and low catalyst load (0.001 – 0.1 mol%) allow high values of TON (up to ~ 104 – 105) and TOF (up to ~ 103 – 106) to be reached. This approach is applicable to a wide range of unsaturated compounds, such as functional and nonfunctional terminal or internal alkenes, alkynes, and alkyl-, phenyl-, and siloxy-containing hydride silanes. Moreover, the heterophase catalytic system is suitable for the synthesis of linear and cross-linked polyorganosiloxanes. In most cases, the reaction provides high yields (up to 95-99%) and selectivity. It gives mostly anti-Markovnikov products which can be isolated from the catalytic system by simple decantation. The process is scalable to gram quantities.