Study On The Synthesis Of Cyclic Carbonates

In the field of chemical research today, cyclic carbonates are an important kind of compounds, which can be used as polar aprotic solvents, organic synthesis intermediates and polymer precursors.To be specific, they can be used in organic synthesis, battery electrolyte and the field of supercritical fluid separation technology. Study on the synthesis method has become a hot topic at present.This paper mainly studied the synthesis of 1,3-dioxan-2-one and its homologue propylene carbonate for synthesis of cyclic carbonates. This paper tries to find a method of low cost,which was non-toxic, easily controlled and suitable for industrialization of different kinds of cyclic carbonates. In this paper,1,3-propanediol (1,2-propanediol) and dimethyl carbonate were used as raw materials respectively for synthesis of 1,3-dioxan-2-one and propylene carbonate. The optimal condition for the synthesis of 1,3-dioxan-2-one:using zinc acetate as catalyst, the reaction temperature was 85℃,the reaction time was 10h, the molar ratio of DMC to 1,3-propanediol was 1.6:1, the catalyst amount was 5wt% of the 1,3-propanediol. The optimal condition for the synthesis of propylene carbonate:using sodium ethoxide as catalyst, the reaction temperature was 85℃,the reaction time was 10h, the molar ratio of DMC to 1,3-propanediol was 1.6:1, the catalyst amount was 5wt% of the 1,2-propanediol.Then we studied the mechanism of ester exchange reaction briefly.This paper studied the use of BTC for cyclo-carbonylation for the first time.The alcohol reacts with BTC to get the corresponding cyclic carbonates,this method hasn’t been reported before. The optimal condition for the synthesis of 1,3-dioxan-2-one:using chloroform as solvent and pyridine as catalyst, the reaction temperature was 60℃, the reaction time was 5h, the molar ratio of 1.3-propanediol to BTC was 2.4:1, the catalyst amount was 3wt% of 1,3-propanediol.The optimal condition for the synthesis of propylene carbonate:using chloroform as solvent and pyridine as catalyst, the reaction temperature was 60℃,the reaction time was 5h, the molar ratio of 1,2-propanediol to BTC was 2.4:1, the catalyst amount was 3wt% of 1,2-propanediol.The mechanism of this method was briefly speculated in this paper. Then this method was used to expand the substrate scope and we got satisfactory yield of ethylene carbonate under the optimal condition. It is found that the method could be used in the synthesis of cyclic carbonates with much higher yields.The kinetics of the reaction between 1,3-propanediol(1,2-propanediol) with BTC was further studied in this paper. The results showed that the reaction was a kind of first order reaction. The apparent activation energy of the reaction between 1,3-propanediol and BTC was 101.3KJ/mol and the pre-exponential factor was 28.454 s-1. The apparent activation energy of the reaction between 1,2-propanediol and BTC was 84.5KJ/mol and the pre-exponential factor was 22.449s-1.