Objective In order to improve the yield of tert-butylphenyl diphenyl phosphate(BPDP) synthesized by one-pot method, alkyl imidazole hydrogen sulfate ionic liquids with different spatial structures and electronic groups were used as catalysts.

Methods This study compared the effects of N-alkyl imidazole hydrogen sulfate ionic liquids with different carbon chains and alkyl imidazole hydrogen sulfate ionic liquids with different electronic groups on the yield of BPDP synthesis, and further investigated the effects of catalyst dosage and catalyst circulation on the yield.

Results When the side chain structure of the catalyst is ethyl, the yield of BPDP is the highest. Electron-absorbing groups can increase the yield of BPDP, while electron-donating groups can reduce the yield of BPDP. The yield of BPDP is the highest when the catalyst dosage is 1.5 w% of 4-tert butylphenol. The catalyst still has high catalytic activity after 6 cycles of useage.

Conclusions The spatial structure and electronic groups of ionic liquid catalysts have a significant effect on the yield of BPDP. When 1-ethyl-2-fluoro-imidazole hydrogen sulfate ionic liquid is used as the catalyst, the yield of BPDP can increase to 85.3 w%, thereby economic benefits can be improved.