熔融结晶制备高含量异噁草松

Preparation of High-content Clomazone by Melt Crystallization

利用石油醚与异噁草松原药混合来降低物料黏度,采用程序降温设备,以0.5℃/h的速率控制结晶速率,保证结晶过程有效地排出杂质,通过结晶排出液体溶剂带走大量杂质,然后加入新鲜石油醚,15℃左右发汗1 h,洗涤除去附着在晶体表面的杂质。结果表明:异噁草松原药[含量(质量分数,下同)为75%]通过一步结晶能够得到含量94%以上的合格产品,收率达到60%;针对合格品进一步采用二次结晶的方法,能够使异构体含量降低到0.1%以下,达到一级品的质量,同时物料结晶的结晶热一般为汽化热的1/5~1/7,有效降低产品的能耗;采用10~50℃低温生产方法代替传统的高真空精馏(温度为170~200℃),避免异噁草松高温分解的危险,在工艺安全性上更加优越。

Petroleum ether and raw drug of clomazone were mixed to reduce the viscosity of materials.The programmed cooling equipment was adopted to control the speed of crystallization at a rate of 0.5℃/h to ensure the effective expulsion of impurities in the crystallization process.After crystallization,fresh petroleum ether was added and sweated for 1 hour at 15℃,and then impurities attached to the crystal surface were removed by washing.Results showed that a qualified product with a content of more than 94%could be obtained through one-step crystallization from the original medicine of clomazone with mass fraction of 75%,and the yield reached 60%.The second crystallization method was further used for qualified products,the isomer content could be reduced to below 0.1%to reach the quality of the first-class product,and the crystallization heat of the material was generally 1/5 to 1/7 of the heat of vaporization,which effectively reduced the energy consumption of the product.The 10-50℃ low temperature production method was adopted to replace the traditional high vacuum distillation(170-200℃),avoiding the decomposition of clomazone at high temperature,and the technic was more superior in process safety.