Recyclable Pt‐Catalyzed Biphase Hydrosilylation on Water: From Functionalized Monomers to Polymer Materials

ABSTRACT Ways to resolve the main challenges of the important industrial hydrosilylation process are proposed. Recyclable biphasic Pt/H 2 O‐ and Pt/K B r/H 2 O ‐catalysts are developed. They are prepared by dissolving K 2 PtCl 4 with or without KBr in H 2 O at r.t. for 2 min. Mechanistic studies revealed that previously unknown highly catalytically active single‐atom ( Pt/H 2 O ) or cluster ( Pt/K B r/H 2 O ) [Pt 0 ]‐complexes are generated. H 2 O, Cl – /Br – , and alkenes/alkynes coordinate such [Pt 0 ]‐species, “tuning” their stability, catalytic activity, and structure (single‐atom or cluster). The cooperation of [Pt 0 ]‐species and “on water” effect enabled high efficiency in hydrosilylation. Using Pt/H 2 O and Pt/K B r/H 2 O , a wide range of hydrosilanes, including oligomeric and polymeric ones, as well as aliphatic and aromatic alkenes and alkynes with functional groups, were employed to prepare anti ‐Markovnikov products. Pt/K B r/H 2 O made it possible to obtain cured monoliths and thin films from PDMS derivatives with Si–H‐groups, and vinylsiloxanes, dienes, including gaseous acetylene or butadiene. Pt‐free products, including cross‐linked materials can be isolated from the biphasic catalytic system by decantation. The recyclability (≥15 cycles), low Pt‐loadings and high yields enable a low E‐factor (≤0.07) and a high TON (>10 4 ). Furthermore, a constructed tube‐in‐tube flow reactor allows for effective scale‐up, automatic separation and recycling of the catalytic system with continuous product synthesis.