Synthesis And Technology Of2,3-Dichloropyridine

In recent years, in the fields of fine chemicals, such as pesticide andmedicine, etc., pyridine compounds play an more and more important role.In this thesis, the recent advances in the studies on the development andsynthesis of pyridine derivatives and a novel anthranilic diamidesinsecticide chlorantraniliprole were reviewed, and the key intermediate ofchlorantraniliprole-2,3-dichloropyridine was chosed as researh topics.Two ways of synthesizing of it were researched.Part one: Synthesis of2,3-dichloropyridine started with nicotinamide.In this section, the advantages and disadvantages of various syntheticmethods were compared and cheap nicotinamide had been chosed as rawmaterials to prepare2,3-dichloropyridine by way of Hofmann degradation, chlorination, diazotization sandmeyer reaction.The optimum conditionsfor each part were determined by batch experiments, and the total yieldwas about64.7%. As the intermediates of this route,3-aminopyridine and2-chloro-3-aminopyridine also have a very wide range of applications inpesticide and pharmaceutical fields. Compared with the traditional methodwith2-chloronicotinic acid as raw materials, the route presentd here wasmore environment-friendly, simple and easy to achieve.Part two: Synthesis of2,3-cichloropyridine started with3-cyanopyridine.2-chloron icotinamide is a key intermediate of2,3-dichloropyridine. By comparison among different routes, we hadselected cheap3-cyanopyridine as raw materials, through nitrogen oxide,chlorination and hydrolysis to prepare the target compound. Through theoptimization of the process, the total yield was76.9%. The intermediate ofthis route,2-chloro-3-cyanopyridine has an important role in the fields ofpesticide and medicine. Compared with other routes, this route was notonly easy to implement but also to improve the yield.