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 inert atmosphere, at r.t. It was found that mononuclear Pt0-complex generated in the catalytic system is a single-atom catalyst. The method enables 36 recycles with quantitative yield in air at r.t. The reaction proceeds at a high rate even with small catalyst loadings. High values of TON (up to 105) and TOF (up to 106) were achieved. This approach is applicable to a wide range of unsaturated compounds, such as terminal or internal alkenes, alkynes, and alkyl-, phenyl-, and siloxy-containing hydrosilanes. Moreover, the heterophase catalytic system is suitable for 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.