The invention relates to a method for preparing
polycarbonate through basic
ionic liquid catalysis. The method is characterized in that
quaternary ammonium and
quaternary phosphonium basic
ionic liquid serves as a catalyst, the dosage of the catalyst is 5*10<-3>%-5% that of a dihydroxy compound, the dihydroxy compound and dialkyl
carbonate serve as the raw materials, the feeding
molar ratio of the dihydroxy compound to dialkyl
carbonate is 1:0.8 to 1:10, and
polycarbonate is synthesized through melting ester exchange. The synthetic processes of
polycarbonate comprise the two stages of ester exchange and polycondensation, wherein for the ester exchange stage, on the condition that the
reaction temperature ranges from 98 DEG C to 150 DEG C, the pressure is
atmospheric pressure, and the reaction time ranges from 3 h to 6 h,
prepolymer is obtained, and for the polycondensation stage, polycarbonate is obtained by synthesizing the
prepolymer on the condition that the temperature ranges from 210 DEG C to 260 DEG C, the vacuum degree ranges from 4.0*10<-3> MPa to 1.0*10<-5> MPa, and the reaction time ranges from 1 h to 7 h. The synthetic method has the following advantages that the catalyst is simple in component and high in activity, a by-product
phenol can be recycled, and the cost is reduced; toxic
phosgene is cleared off, and the method is
environmentally friendly;
zero emission is almost achieved, and the method completely conforms to the concept of cleaning production.