Preparation of Trimesoyl Chloride from Trimesoyl Acid Using Triphosgene

Trimesoyl chloride(TMC) was prepared from trimesic acid(TMA) using triphosgene at room temperature.The best result was that trimesic acid reacted with triphosgene at room temperature in the presence of imidazole/DMF using tetrahydrofuran as solvent to give TMC in 88% yield.Purity of the product was more than 99.2%,and its melting point was 32.5~33.6 ℃.Effects of catalyst and solvent on the reaction were discussed.In the presence of single catalyst,such as dimethylformamide (DMF),pyridine,imidazole and triethylamine,the yields were all below 32%,while in the presence of binary catalyst,such as pyridine/DMF and imidazole/DMF,the yields were higer than 60%.Speed of the reaction depended on the solvent to some extent because it is good for the heterogeneous reaction mixture to dissolve the product (TMC) into the solvent quickly; it spent less time to become homogeneous if the solubility parameter of solvent was close to that of TMC.The mole ratio n(BTC)/n(TMA) was an important factor in the reaction.The yield was nearly zero if n(BTC)/n(TMA)1.2,and increased with the increase of the mole ratio until n(BTC)/n(TMA)3.