Continuous Synthesis Of 2,3-Dichloropyridine In A Microreaction System

2,3-Dichloropyridine is a key raw material of a novel anthranilic diamides insecticide chlorantraniliprole. Chlorantraniliprole has a novel mode of action with unique chemical structure and shows excellent efficacy, abroad insecticidal spectrum against lepidopterous insect pests, excellent safety for mammalian.Based on the principle of environment friendly, the demand of 2,3-Dichloropyridine will increase with the development of insecticide requirements. However, the synthesis process of 2,3-Dichloropyridine is not mature at home and abroad, which leads to small production and high price. Therefore, it is helpful and useful for society and economy to explore a suitable route for industrialization.In this essay, the 2,3-Dichloropyridine is successfully synthesized both in batch reactor and in the impinging-microrector. The effect of some influent factors on yield of 2, 3-Dichloropyridine has been systematically investigated, including molar ratio of the reactants, mixing, the feeding rate, concentration and quantity of H2O2, residence time, temperature and different catalysts. This experiment contains three parts, including chlorination, diazotization, and sandmeyer reaction starting with 3-aminopyridine. HPLC have been used to characterize the products. Under the optimized condition, the yield is beyond 75% in micro-reactor and 65% in batch reactor, and the result in micro-reactor is better than that in batch reactor because of the better heat transfer and mass transfer.In order to purify the product, Aspen is used to simulate the process. We find the best feeding stage and reflux ratio to achieve 2,3-dichloropyridine with the yield of 99%.