Improvement On The Synthesis Method Of 2-Chloro-5-Chloromethylpyridine And Its Application

2-chloro-5-chloromethylpyridine is an important pesticide intermediate,involves the synthesis of many kinds of pesticides such as imidacloprid,acetamiprid,nitenpyram,thiacloprid,which are used widely in the market.The traditional synthetic methods of 2-chloro-5-chloromethylpyridine each has its own advantages and disadvantages,which were all produced under certain historical conditions.With the development of organic chemical methodology,to explore and develop the synthetic route which has advantages of simple operation,high yield,low cost and less environmental pollution always have great economic value and academic significance.This thesis explored the synthetic routes of 2-chloro-5-chloromethylpyridine based on the previous literatures and a number of related experiments,and studied the synthesis of imidacloprid and acetamiprid with the intermediate.This thesis designed a new synthetic route of 2-chloro-5-chloromethylpyridine,this route used the cheap DL-malic as starting materials for the synthesis of 2-chloro-5-chloromethylpyridine,firstly coumalic acid was obtained via the cyclization of DL-malic in the role of concentrated sulfuric acid,the yield was 79.8%;then methyl coumalate was obtained through esterification between coumalic acid and methanol under the catalysis of concentrated sulfuric acid,the yield was 88.9%;after that the methyl coumalate via ammonolysis and hydrolysis by ammonia water and sodium hydroxide got the 6-hydroxynicotinic acid,the yield was 92.7%;then it was treated with phosphorus pentachloride under the catalysis of phenylphosphonic dichloride to give 2-chloro-5-trichloromethylpyridine,the yield was 88.6%;finally the 2-chloro-5-trichloromethylpyridine synthesized the object product 2-chloro-5-chloromethylpyridine by reduction with zinc powder,the yield was 76.8%.The total yield of the five step reaction was 44.7%.This route has not been reported in the literatureas and it has the advantages of less waste water,low cost,mild reaction conditions and so on,which has the potential of further industrial application.At the same time this thesis also made some useful exploration on the 2-chloro-3-methylpyridine which was produced as by-product in traditional rote of 3-methyl pyridine oxidation for the synthesis of 2-chloro-5-chloromethylpyridine.Then this thesis adopted the self-prepared 2-chloro-5-chloromethylpyridine as raw material to synthesize imidacloprid via condensation with imidazolidine which was synthesized by two-step reaction,and recycled the excess imidazolidine which was in order to further reduce the cost.The total yield of the three steps reaction was 89.6%.Finally,this thesis also used the self-prepared 2-chloro-5-chloromethylpyridine as raw material to synthesize acetamiprid via condensation with 2-amino-2-methylpropane nitrile which was synthesized by three-step reaction,the total yield of four steps reaction was 72.6%.In this thesis,the resulting spectrum of the key intermediates and target products are related to the structural characteristics of the compounds.