Preparation method of thifluzamide

Abstract

The invention belongs to the technical field of pesticide chemistry, and particularly relates to a preparation method of thifluzamide. The preparation method comprises the following steps: with 2-methyl-4-trifluoromethyl-5-thiazolecarboxylic acid as a raw material, performing an acylating chlorination reaction on the raw material and an acylating chlorination reagent in a solvent under the actionof a catalyst, then performing an amidation and condensation reaction on a product and 2,6-dibromo-4-trifluoromethoxyaniline under the catalytic action to obtain a final product thifluzamide. The thifluzamide product prepared by the preparation method provided by the invention has the yield range of 87-92% and the crude product content being higher than or equal to 96%; by the preparation method,the operation is simple, acyl chloride is not required to be purified, the preferred catalyst has an obvious effect and the overall reaction cycle is short.

Description

technical field [0001] The invention belongs to the technical field of pesticide chemistry, and in particular relates to a high-efficiency preparation method of the fungicide thifuramide. Background technique [0002] Thifluzamide, also known as Thifluzamide, belongs to the thiazole amide fungicides with strong systemic conductivity and long-lasting effect. It is active against pathogenic fungi such as Rhizoctonia, Puccinia, Stiltia, Tilletia, Puccinia, and Sclerotinia, especially for diseases caused by Basidiomycetes such as striae Blight, blight and other special effects. Thiofuramide has excellent high efficiency, low toxicity and broad-spectrum properties. [0003] Utilize the technology of intermediate 2-methyl-4-trifluoromethyl-5 thiazole carboxylic acid to prepare thifluxamide at present and mainly be divided into two classes: one is step-by-step reaction, and thiazole carboxylic acid first carries out acyl chloride reaction, then with 2, 6-dibromo-4-trifluorometho...

AI Technical Summary

Problems solved by technology

Using step-by-step reaction method, thionyl chloride is used as acyl chloride reagent in the technical scheme disclosed by patent EP0371950A2, and acid chloride is distilled in high vacuum for amidation, but the yield is too low to be suitable for industrial production; Chinese patent CN102746254A uses thionyl chloride as Acyl chloride reagent, followed by direct amidation, the yield has increased, but it is still relatively low. It has been verified that the residual thionyl chloride is prone to side reactions with 2,6-dibromo-4-trifluoromethoxyaniline, forming Tar-like black viscous matter, which affects the yield and product quality; and the reaction cycle is long, sulfur dioxide is generated in the process, which increases the difficulty of subsequent tail gas treatment, and does not meet the requirements of industrial continuous production from the perspective of product competition of production enterprises

The second is a one-step reaction. Chinese patent CN108059625A uses thiazole carboxylic acid and 2,6-dibromo-4-trifluoromethoxyaniline to dissolve in acetonitrile solvent, and then adds a catalyst for direct reaction. The essence of this reaction still belongs to a step-by-step reaction. The catalyst used is actually an acyl chloride reagent, and the amount added has exceeded the amount of the raw material intermediate, so it is equivalent to replacing the acyl chloride reagent, instead of adding a catalyst, it is actually still an acid chlorination followed by amidation reaction; at the same time, dropwise addition is used in this technical scheme feeding method, the overall reaction cycle is still long, the crude product content is low, and subsequent recrystallization operations are required. After the solvent used is acetonitrile and water miscibility, separation is difficult; and the reaction requires an anhydrous environment, so it is not conducive to solvent reuse in industrial production. ; The selected reagents will inevitably produce phosphorus-containing wastewater, and the subsequent treatment of eutrophic wastewater will also affect the cost of industrialization and is also not conducive to industrialization