The cooperative role of zwitterions and phosphotungstate anion in epoxidation reaction

•The combination of zwitterion and phosphotungstate constructed a catalyst.•The combined catalyst exhibited high TON and TOF values for expoxidation.•The epoxidation can be performed under solventless and ice bath conditions.•Strong cooperative effect existed between zwitterions and phosphotungstate.•The formation of W/O emulsion by the zwitterion facilitated the reaction.

The combination of a certain zwitterion and sodium phosphotungstate provided an excellent catalyst for the epoxidation of cyclooctene: high TON was available even without any solvents and under ice bath condition. Based on characterizations by 1H, 13C and 31P NMR as well as FT-IR, Raman and UV–vis methods and investigations on the catalytic performance of the binary system, strong cooperative effect between zwitterions and sodium phosphotungstate was demonstrated. Here, the formation of stable W/O emulsion by the amphiphilic zwitterions seems to be crucial, which allows cyclooctene being in sufficient contact with the active phosphotungstate anions in the water phase.

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