Study On The Synthetic Process Of Tolfenpyrad

Tolfenpyrad, a new type of insecticide and acaricide developed by the Japanese Mitsubishi Chemical Holdings Corp in 1988 is known for its high efficiency, broad spectrum, low toxicity and quick effect.This study takes diethyl oxalate and butanone as raw materials to obtain Tolfenpyrad By optimizing the conditions such as the reaction temperature and feeding method, the amount of ethyl 3-methyl-2,4-dioxovalerate, the by-product of Claisen condensation reaction, has been effectively reduced. Thus the reaction rate and the purity of the product have been improved. In Knorr reaction, hydrazine hydrate is applied as cyclization reagent and water as organic solvent, the cost of raw materials has been reduced, avoiding the use of organic solvents. In the reaction of methylation, methyl carbonate has been used to replace dimethyl sulfate, reducing the cost of raw materials and avoiding the use of highly toxic agents. In halogenation reaction, chlorine has been employed to take the place of sulfonyl chloride, lowering the cost. When the tail gas is absorbed for other steps of reaction, the by-products are effectively utilized, resulting in the reduction of the pollution to the environment. In the course of the synthesis of acyl chloride, phosgene replaces thionyl chloride when the exhaust is absorbed for other steps. In etherification reaction, 4-(4-methylphenoxy)benzylamine has been synthesized by a two-step reaction, with high yield, high content of preparation, less waste, and low cost. During hydrogenation, Raney nickel is likely to be recycled repeatedly as a catalyst, with ammonia gas to substitute for ammonia water, making solvent recovery less difficult and the process simpler and stabler. Tolfenpyrad is synthesized under moderately stable conditions, with triethylamine as an acid-binding agent, achieving a high yield. This thesis focuses on the analysis and synthesis of the major impurities in Tolfenpyrad, along with the analysis of their structures.The engineering design has been optimized as follows. The chlorination and hydrolysis reaction are integrated into desolution, and the drying process of the intermediate 4-Chloro-3- ethyl-1-methyl-1H-pyrazole-5-carbonyl acid and 4-(4-methylphenoxy) benzylamine has been relieved. This design has greatly reduced the reaction cycle, increased the output per unit time, and also cut the investment in the reaction kettle, metering tank and drying equipment.At present, the total yield of the process is 58.3%(by butanone), the product content is more than 96%, and the yield is much higher than that of the reported literature. Through experiments under optimized conditions, the cost of raw materials is 77,000 yuan/ton, while the current market price is about 320,000 yuan/ton, reaping remarkable economic benefits and social benefits.