Green Synthesis Method And Environmental Impact Assessment Of Vinylene Carbonate

Vinylene carbonate (VC) is an important additive for lithium ion battery because of its high dielectric constant and stability. In order to improve the two step synthesis process of VC, the following research had been done.(1) Chlorination reaction:orthogonal experiment was used to get the optimal reaction conditions under water bath heating:n(EC):n(AIBN)=600:1, the n(SO2Cl2):n(EC)=1.3:1, reaction time was100 min, reaction temperature was73℃, the yield of chlorinated vinylene carbonate was 82.3%; n(EC):n(AIBN) and n(SO2Cl2):n(EC) were found to be significant influencing factors for the process. The optimal reaction conditions for microwave heated chlorination process was found to be:microwave power was 100W, sulfonyl chloride adding time was 20min, n(SO2Cl2):n(EC)= 1.4:1, n(EC):n(AIBN)=600:1, the reaction time was 15 min, the yield of chlorinated vinylene carbonate was 83.1%. The reaction time of microwave heated process was only 15% of water bath heated process, while the yield was a little higher.(2) Dimethyl carbonate (DMC) and acetone was used as the solvent for dechlorination reaction respectively. The yield in DMC was higher than that in acetone. The optimum reaction conditions were found to be:reaction temperature 60℃, add time 40 min, n(TEA):n(Cl-EC)=1.5:1, reaction time 6h, the yield of VC was 73.3%. The kinetics equation of dechlorination reaction heated by water bath was:(3) The dechlorination process under microwave heating was also examined. The yield and reaction time of microwave heated process were better than those of water bath heated process in acetone. The optimal reaction conditions under microwave radiation were found to be:microwave power 100W, TEA adding time 40min, n(TEA):n(Cl-EC)= 1.5:1, reaction time 70min, the yield of VC was 75%. The kinetics equation of dechlorination reaction under microwave radiation was:The kinetics data obtained under microwave radiation fitted well with the equation obtained from water bath heated process, Which implied that the acceleration of reaction was mainly because of the thermal effect.(4) Energy efficiency and green degree method were used to compare the impact of microwave heated process and water bath heated process respectively, and the results were consistent. The environmental impact of microwave heated process accounted for only 15-25% of that of water bath heated process. The energy efficiency was found to be the highest at 100W for chlorination process and 75W for dechlorination process.