Preparation method of mesotrione

Abstract

The invention provides a preparation method of mesotrione. The preparation method comprises: S1) carrying out a reaction on 2-nitro-4-methylsulfonylbenzoyl chloride and 1, 3-cyclohexanedione in the presence of an acid-binding agent to obtain an enol ester reaction liquid; and S2) adding a rearrangement agent as shown in a formula (I) into the enol ester reaction liquid, and performing a rearrangement reaction to obtain mesotrione. Compared with the prior art, the method has the advantages that the rearrangement agent containing unsaturated double bonds is adopted, under the synergistic effect of the double bonds, the rearrangement agent has better reactivity and reaction rate in the rearrangement reaction process, and the green and environment-friendly aftertreatment method is simple.

Description

technical field [0001] The invention belongs to the technical field of chemical industry, in particular to a preparation method of mesotrione. Background technique [0002] Mesotrione belongs to cyclohexanedione herbicides. It has a good control effect on the most difficult broad-leaved weeds in corn fields and ensures the healthy growth of growing crops. It is not only safe for corn, but also harmful to the environment and subsequent stubble. crop safety. [0003] The currently reported synthesis route of mesotrione is mainly based on the esterification of nitro-4-methylsulfonyl-benzoyl chloride to form the corresponding enol ester, followed by rearrangement to prepare mesotrione. Wherein the difference is that the main difference is that the catalyst and the acid-binding agent are different in the rearrangement process. For example, the U.S. Patent No. US5886231 discloses that sodium carbonate is used as an alkaline reagent, and the enol ester is rearranged to prepare nit...

AI Technical Summary

Problems solved by technology

Wherein the difference is that the main difference is that the catalyst and the acid-binding agent are different in the rearrangement process. For example, the U.S. Patent No. US5886231 discloses that sodium carbonate is used as an alkaline reagent, and the enol ester is rearranged to prepare nitric acid under the action of sodium cyanide. Grassone and sulcotrione, the rearrangement catalyst sodium cyanide used in them is highly toxic, and at the same time, it remains in the water phase, which increases the difficulty of wastewater treatment; the Chinese patent application number CN201610994931.7 discloses a synthesis of mesotrione process, the 2-nitro-4-methanesulfonylbenzoic acid obtained through nitration and oxidation continues to obtain mesotrione through acyl chloride and condensation rearrangement. In this process, triethylamine is used as an acid-binding agent, and acetone cyanohydrin is used as Rearrangement agent, the purity of the product obtained is 92.6%, and the yield is 89.41%, but this method also uses highly toxic acetone cyanohydrin; the patent No. TW089115906 discloses a method for preparing acylated 1,3-dicarbonyl The compound method, the rearrangement of this method is carried out in the presence of an alkali metal azide, but due to the explosive nature of the azide itself, it has high requirements for the reaction and treatment process; the application number is CN200910155470. The Chinese patent of 4 discloses a synthesis method of triketone compounds. The method rearranges the enol ester under the action of an alkaline reagent and a rearrangement agent, and then acidifies and separates to obtain the target product. It uses triethylamine as the Alkaline reagent, the rearrangement agent is 6-chloropurine, and the synthesis yield is 85%. Although this method avoids the use of highly toxic rearrangement catalysts, the molecular weight of such rearrangement agent compounds is relatively large, which increases the use cost on the one hand, On the other hand, it increases the difficulty of post-processing and purification of the reaction product; the Chinese patent with the publication number CN108440352A discloses a preparation method of mesotrione, which uses p-thiamone-o-nitrobenzoic acid as raw material, and first reacts with The condensation reaction of 1,3-cyclohexanedione gives the intermediate 2-nitro-4-methylsulfonylbenzoic acid-[3'-carbonyl-1'-cyclohexenol]-ester, which is then reacted with an inorganic base and a basic Under the co-catalysis of strong tertiary amine organic bases, the rearrangement of enol esters is carried out to obtain the acylated cyclic 1,3-dicarbonyl compound mesotrione. Although this method avoids the use of highly toxic cyanide compound catalyst, but the participation of a large number of inorganic bases not only increases the cost of raw materials, but also causes difficulties for the subsequent treatment process; "Pesticide Science and Management" (2018,039(001):36-40.) reported that Green synthesis, which uses 2-nitro-4-thiamphenicol benzoic acid as a raw material to prepare mesotrione through three steps of chlorination, condensation, and rearrangement. The rearrangement catalyst is acetonitrile instead of the highly toxic substance cyanide Potassium, acetone cyanohydrin, although this method has avoided the use of highly toxic catalyst, has improved the safety factor in the reaction, but when adding catalytic amount of acetonitrile, the effect is extremely limited, and adding in a large amount not only reduces the utilization rate of the device, but also increases the Separation difficulty of subsequent mixed solvents

Images