Heterogeneous phosphonium–carbon based PTC catalyst: From mechanochemical synthesis to SN2 type reaction in water

•The application of a new phosphonium-carbon-based phase-transfer catalyst (PTC) synthetized by mechanochemical approach is studied.•The new heterogeneous PTC is fully characterized and used for SN2 type reaction of NaSCN with variously substituted benzyl bromides.•Using 5mol% catalyst in water can result in over 99% conversion of the reaction.•Being heterogeneous, the phosphonium-carbon-based PTC catalyst can be easily recovered in an aqueous solution and recycled without any loss in efficiency even after five runs.