申请人:Rutgerswerke Aktiengesellschaft
公开号:US05380862A1
公开(公告)日:1995-01-10
A process for the preparation of isomer-free 2,5-dichloropyridine comprising alkoxylating 2-chloro-pyridine or 2-bromo-pyridine in the presence of a base at elevated temperatures, chlorinating with gaseous chlorine the alkoxylated product at ambient temperatures in an aqueous suspension in the presence of an auxiliary base, a small amount of a catalyst and optionally a small amount of an emulsifier, treating the isomer reaction mixture with a Vielsmeyer-Haack reagent, subjecting 2,5- and 2,3-dichloropyridine mixture to water vapor distillation and crystallizing the crystalline product from an alcohol-water mixture.
制备无异构体2,5-二氯吡啶的过程包括在高温下在碱存在下烷氧基化2-氯吡啶或2-溴吡啶,然后在常温下在水悬浮液中用气态氯气氯化烷氧基化产物,在辅助碱存在下,加入少量催化剂和可选的少量乳化剂,用Vielsmeyer-Haack试剂处理异构体反应混合物,将2,5-二氯吡啶和2,3-二氯吡啶混合物经过水蒸气蒸馏,并从醇-水混合物中结晶化结晶产品。