溶剂法合成四氯苯酐工艺的改进

在溶剂法基础上，以苯酐为原料，复合碘作催化剂，产品直接结晶分离的方法合成四氯邻苯二甲酸酐。改进后的工艺反应温度低，反应时间短，后处理简单，溶剂和催化剂可回收使用，确定了最佳合成工艺条件，反应时间12h，反应温度70－120℃，催化剂用量为苯酐质量的1％，溶剂氯磺酸用量为苯酐质量的5．5倍。上述条件下，产品四氯苯酐的纯度达99％，收率为98％。

Improvement in Synthesis of Tetrachlorophthalic Anhydride by Solvent Method

Tetrachlorophthalic anhydride was synthesized with phthalic anhydride as raw material, compounded iodine as catalyst by direct separation of crystal from solvent on the basis of solvent method. The improved synthesis has characters of low reaction temperature, short reaction time, convenient after-treatment and recovery and reuse of solvent and catalyst. The optimum conditions of synthesis were determined as follows: reaction time 12 h, reaction temperature 70～120 ℃， catalyst amount(based on the amount of phthalic anhydride) 1%, chlorosulfonic acid solvent amount 5.5 times as much as phthalic anhydride. Under such conditions the purity and the yield of tetrachlorophthalic anhydride was up to 99% and 98% respectively.