三光气法制备均苯三甲酰氯

常温下,采用三光气与均苯三甲酸在催化剂作用下制备均苯三甲酰氯(TMC),最佳收率可达88%。产品熔点为32.5~33.6℃,w(TMC)>99.2%,IR图谱与标准谱基本一致。通过对催化剂、溶剂和反应底物配比等影响因素的研究发现:(1)在常温下单一催化剂,如N,N-二甲基甲酰胺、吡啶、咪唑、三乙胺等不能让反应进行完全,收率<32%;而用复合催化剂,如吡啶/N,N-二甲基甲酰胺、咪唑/三乙胺等在常温下能反应完全,收率>60%。(2)溶剂的溶度参数与均苯三甲酰氯的溶度参数相差越小,反应速度越快。(3)反应底物配比n(三光气)/n(均苯三甲酸)<1.2时,几乎得不到产品,随着n(三光气)/n(均苯三甲酸)增大,收率增高;当n(三光气)/n(均苯三甲酸)>3后,其增大对产品收率影响不大。

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.