Polymeric bis(triphenylphosphine)iminium chloride as a recyclable catalyst

Metal-free catalysts have garnered considerable interest as an environmental and economical alternative to precious metal catalysts. Bis(triphenylphosphine)iminium chloride (PPNCl) has emerged as a prominent choice due to its air and thermal stability and broad reactivity, especially in applications where a bulky cation is needed. The high phosphorus content and synthetic effort required for catalyst synthesis increase environmental impact; the recyclability of PPNCl in catalytic processes remains largely unexplored. The potential development of a polymer-supported PPNCl catalysts therefore desirable to enable this recyclability. In this work, we synthesise polymeric PPNCl ( poly(PPNCl) ) for the first time. Poly(PPNCl) demonstrates a comparative catalytic reactivity to its small molecule variant when employed as a catalyst in halogen-exchange reactions and CO 2 /epoxide coupling. For the latter the effect of catalyst loading, CO 2 pressure, reaction time and addition of co-catalyst on conversion and selectivity was investigated. Poly(PPNCl) was easily recovered from the crude product by simple precipitation and its catalytic reactivity was well-maintained over three reaction cycles, providing environmental and economic advantages for sustainable reaction development. The powerful PPNCl catalyst can be converted into a recyclable and more soluble polymeric version through post-polymerisation modification of a triphenylphosphine-decorated copolymer.