2-氯烟酸合成工艺改进

New Synthesis Method of 2-Chloronicotinic Acid

以氰基乙酸乙酯为原料,经氯化、环合、水解得2-氯烟酸。将氯化反应的二氯与一氯产物比例控制在(48∶50)～(50∶48),省去氯的重分配这一单独操作,并选用甲苯-甲醇钠作为迈克尔加成的反应体系,环合反应时采用分段反应,结果反应更易于控制,整个反应过程更加简练,减少了操作;反应总收率提高到了66.5%。

2-Chloronicotinic acid was synthesized from ethyl cyanacetate by the reactions of chlorination;cyclization and hydrolysis.The reaction conditions were optimized.Compared to the classical literature method,the rate of double-chlorinated and single-chlorinated product is controlled in within the ratio of（48∶50）^（50∶48）.In the process the redistribution of chlorine was eliminated and toluene-sodium methoxide was used as the reaction solvent of Michael addition.Another improvement was the two-step reactions used in cycllization.These optimizations can make the control of reaction easier and more concise.The total product yield is increased to 66.5%.