反应-结晶法生产对甲苯磺酸

运用部分结晶选择性原理制备对甲苯磺酸。甲苯与浓硫酸在甲苯沸腾回流(110°C)的条件下反应5h后在80°C下加水使对甲苯磺酸结晶水合物从磺化混合液中析出,而间位和邻位两种异构物留在体系中,补充原料后继续反应,体系重新达到化学平衡状态,再析出产品。如此循环反应-结晶过程,即抑制了新的间位和邻位异构物进一步产生,又使较纯的对位产物分离出体系。优化了工艺条件,结果表明,该生产工艺路线为硫酸定量反应,无废酸或甲苯排放,产品纯度大于98%,循环反应8次,收率可达90%以上。对于高选择性生产对甲苯磺酸和清洁磺化过程具有重要的意义。

Preparation of p-Toluenesulfonic Acid

p-Toluenesulfonic acid was prepared by the reaction-crystallization method.It was formed when toluene and sulfuric acid were refluxed at (110°C).At the end of the reaction the mixture was cooled to (80°C)and water was added.The monohydrate p-toluenesulfonic acid was crystallized while the o and m-isomers remained in the solution Then,the reagents were added again and the reaction was recycled.This process does not discharge waste acid or toluene,and the yield and purity of the product reaches 90% and 98%,respectively.