Study on the synthesis of quaternary ammonium salts using imidazolium ionic liquid as catalyst

Various tetramethyl ammonium salts and N,N,N-trimethyl-N  -cyclohexyl ammonium salts with different anions were synthesized efficiently by a one-step reaction. The effects of the catalyst content, reaction temperature, and reaction time on the product yield were investigated. Under similar reaction conditions, the maximum yields of tetramethyl ammonium salts decrease corresponding to the anion type of the starting ammonium salts is Br−,Cl−,NO3−>F−,SO42−>C2O42−,CO32−,OAc−. For the N,N,N-trimethyl-N-cyclohexyl ammonium salts with anions such as Br−, Cl−, and NO3−, quantitative yields (>99%) can be achieved at 413 K within 8 h or at 443 K for 2 h. The yield of N,N,N-trimethyl-N-cyclohexyl ammonium acetate reaches the maximum (95.7%) at 443 K for 8 h, while the carbonate yield reaches 95.0% at 453 K for 8 h. Quantitative yield of N,N,N-trimethyl-N-cyclohexyl ammonium sulfate is obtained at 443 K for 8 h.