StudV On The Synthesis Of3-difluoromethyl-1-methyl-1H-pyrazol-4-carboxylic Acid

People has began the active and deep exploration of molecular structure, mechanism, biological activity and safety aspects for fluorine-containing and heterocyclic compounds since the21st century. And it has found many heavyweight sterilization products, the representative products are isopyrazam and sedaxane which developed by Syngenta, fluxapyroxad and bixafen which developed by Basf and Bayer. All these products have features of safety, efficiency, unique mechanism, low residue and environment-friendly. And they have a very prospective market over the next ten years.3-Difluoromethyl-1-methyl-lH-pyrazole-4-carboxylic acid is an important intermediate to synthesize isopyrazam. Based on a large number of literature source and research work, we developed a synthetic route of3-difluoromethyl-1-methyl-1H-pyrazole-4-carboxylic acid.The studies in the thesis are summarized as follows:1. N, N-Dimethylaminoethyl acrylate was synthesized with propynol by oxidation, esterification and addition reaction. This method has some advantages of mild reaction was temperate, high yield, simple operation, raw materials and solvents were cheap and easy to get, so it is ready for industrial production.2.3-Difluoromethyl-1-methyl-lH-pyrazole-4-carboxylic acid was synthesized with N, N-dimethylaminoethyl acrylate by substitution, cyclization, methylation and hydrolysis reaction. Using the relatively cheap and smaller molar mass of2,2-difluoroacetic acid for the source of fluorine, the produce method of3-difluoromethyl-1-methyl-1H-pyrazole-4-carboxylic acid has some advantages of mild reaction was temperate, low cost, the content ranges from98.0%to99.0%, which varies from50.3%to53.1%.1H NMR, LC-MS and IR spectra confirmed that the product was3-difluoromethyl-1-methyl-1H-pyrazole-4-carboxylic acid. Having explored the production cost, development of process conditions to lay a foundation for future industrial production.