The Synthesis Of Strobilurin Fungicide Pyraclostrobin

Strobilurin fungicides, which have the advantages of low toxicity, high efficiency, broad-spectrum, excellent systemic activity, long lasting period and so on, is a new kind of fungicides after triazole fungicides with great development potential and market vitality, and pyraclostrobin is a representative one.Two synthetic routes of the strobilurin fungicide pyraclostrobin were systematically researched, focusing on the synthetic optimization of the same intermediate 1-(4-chlorophenyl)-3-hydroxypyrazole and the key steps of the two routes, bromination and reduction. One-pot method was used for the synthesis of 1-(4-chlorophenyl)-3-hydroxypyrazole, which not only simplified the operation conditions, but also increased the total yield. Oxidative halogenation was used for bromination of Route 1, while with NBS for Route 2, and the influencing factors were systematically studied to increase the yield and selectivity. Zinc/ammonium chloride system was used for the reduction of the two routes, and 83%,88% yields were obtained respectively. Compared with the performance of patent method using platinum on carbon catalyst, our method had the advantages of cheap raw material, mild reaction conditions, low equipment requirements, and the disadvantages of relatively low yield and more complex post-processing.In addition, a novel and convenient method for the synthesis of 1-(4-chlorophenyl)pyrazolidin-3-one from 4-chlorophenylhydrazine and methyl acrylate in the presence of base in a ball mill has been described in this thesis, The final yield reached 78% through optimization. The synthesis process was simple and environment friendly.