Preparation method of carfentrazone-ethyl

Abstract

The invention relates to the field of compound preparation, and particularly discloses a preparing method of carfentrazone. According to the method, 1-(5-amino-4-chloro-2-fluorophenyl)-4-difluoromethyl-3-methyl-1H-1,2,4,-triazole-5-ketone (hereinafter referred to as substituted aniline) and acrylamide are used as raw materials; 2-chloro-3-{2-chloro-5-[4-(difluoromethyl)-4,5-dihydro-3-methyl-5-oxo-1H-1,2,4-triazole-1-yl]-4-fluorophenyl}propanamide (hereinafter referred to as substituted benzenepropanamide) is obtained through diazo arylation of amino groups; the substituted benzenepropanamide takes an esterification reaction with ethanol under the existence of sulfuric acid; and the carfentrazone is obtained. The preparing method has the advantages that the process is simple; the reaction conditions are mild; the odor of the raw materials and the odor in production environment are small; the product yield is high; and the industrial production can be favorably achieved.

Description

technical field [0001] The invention relates to the field of compound preparation, in particular to a preparation method of mefentrazone. Background technique [0002] Mefentrazone (also known as carfentrazone-ethyl, mefentrazone-methyl) chemical name is 2-chloro-3-{2-chloro-5-[4-(difluoromethyl)-4,5-dihydro-3- Methyl-5-oxo-1H-1,2,4-triazol-1-yl]-4-fluorophenyl}propionic acid ethyl ester, molecular formula: C 15 h 14 CL 2 f 3 N 3 o 3 , is a triazolinone herbicide with the following structure: [0003] [0004] The main preparation methods of fentrazone are: [0005] Method 1 (WO1990002120, CN1031307C) uses acetonitrile as solvent, molar amount of copper chloride, tert-butyl nitrite as diazotization reagent to diazotize the 5-amino intermediate, and then react with excess ethyl acrylate to obtain of fentrazone. [0006] [0007] Method 2 (WO1997007107, CN1068594C) In an aqueous acetone solution, cuprous chloride is used as a catalyst, and sodium nitrite is used...

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Problems solved by technology

[0012] Both method 1 and method 2 belong to the Meerwein arylation reaction (Meerwein arylation), and both involve diazotization reactions. As we all know, there are many side reactions in diazotization reactions, such as thermal decomposition of diazonium salts, halogenation (Sandmeyer reaction), coupling, etc., which will bring more impurities, and the target product mefentrazone is a viscous liquid, it is difficult to obtain a high-content product through conventional refining methods; method three one On the one hand, an expensive palladium catalyst is used, on the other hand there are also problems of purification; the method tetraacrylic acid is easy to polymerize, the smell is large, the production environment is poor and the yield is low

The raw materials acrylic acid / ethyl acrylate used in the above four methods are liquids with pungent odor, are volatile, and the production environment is poor.

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