Synthesis, Crystal Structure of Protic Pyrazolium Ionic Liquid and Its Catalytic Properties for CO2 Cycloaddition

Two protic pyrazolium ionic liquids(ILs)are synthesized and characterized by mass spectra(MS),1H NMR,13C NMR,and single-crystal X-ray diffraction.Then,their catalytic activity for the cycloaddition of PO and CO2 is investigated.Two protic pyrazolium ILs are the orthorhombic and triclinic systems of space groups Cmca and C2/c for HTMPzBr and HDMPzBr,respectively.They could catalyze the cycloaddition reaction of carbon dioxide(CO2)with epoxides(PO)to produce cyclic carbonate(PC)without any solvent and co-catalyst and show strong catalytic activity when the reaction temperature is over 110℃.