The preparation method of methylsulfuron methyl

Abstract

The invention relates to a preparation method of mesosulfuron-methyl. The method comprises the following steps: taking 4-cyano-2-nitrobenzoate as a starting raw material; firstly performing a nucleophilic substitution reaction with benzyl mercaptan; then, performing reduction hydrogenation by using raney nickel, performing methylsulfonyl acidylation by using methylsulfonyl chloride; then, performing chlorination by using chlorine gas and performing ammoniation by using ammonia gas to obtain a key intermediate, namely 2-methoxycarbonyl-5-methanesulfonyl ammonia toluenesulfonamide; and finally,performing condensation to obtain a target product, namely the mesosulfuron-methyl. A route of the method is mild in reaction process condition; the operation is easy; the method is suitable for industrial mass production; less environmental pollution is caused; and the method is a relatively good novel method for synthesizing the mesosulfuron-methyl.

Description

technical field [0001] The invention relates to the synthesis of organic compounds, in particular to a preparation method of methylsulfuron-methyl. Background technique [0002] Methsulfuron-methyl, also known as Methsulfuron-methyl, chemical name 2-[(4,6-dimethoxypyrimidine 2-aminocarbonyl) aminosulfonyl]-a-(methylsulfonylamino) p-toluic acid Methyl ester is a new type of sulfonylurea herbicide developed by Bayer AG in 2002. Regarding sulfonylurea herbicides, it is the largest class of herbicides in the world. It mainly works by inhibiting acetolactate synthase , Weed roots and leaves absorb, and conduct in the plant body, thereby prompting weeds to stop growing to achieve the effect of weeding. The herbicide has a good control effect on some broad-leaved weeds such as winter wheat, spring wheat annual grass weeds and chickweed, and the demand for herbicide market in my country is showing an upward trend. [0003] At present, the common synthetic method on the methylsulfu...

AI Technical Summary

Problems solved by technology

The patent DE4335297 uses 5-methyl-2-methoxycarbonylbenzenesulfonyl chloride as the starting material, first undergoes amidation reaction, then NBS bromination, azidation, Pd / C catalytic hydrogenation, and then mesylation to obtain Normalize tert-butyl-2-methoxycarbonyl-5-methanesulfonamide methylbenzenesulfonamide, and finally demethylate under the condition of trifluoroformic acid to obtain the target intermediate. Trifluoroformic acid has strong acidity and is easy to corrode production equipment , and the raw materials of this route are not easy to obtain, and the operation is relatively complicated at the same time. The use of sodium azide in industrial production increases the risk of the experiment, which is not conducive to industrial production

[0005] (2) In order to find a relatively convenient synthetic method, Ma Changpeng et al. improved their synthetic route. The patent CN103755603A uses p-toluonitrile as a starting material, and first reacts with chlorosulfonic acid to obtain sulfonyl chloride for ammoniation. Then, it is oxidized under the action of potassium dichromate and concentrated acid, followed by palladium carbon reduction, mesylation, and reflux of methanol to obtain the target intermediate. The reaction route is convenient to operate, and each step is a conventional operation. Potassium dichromate is easy to cause environmental pollution

[0006] (3) At present, the Bayer patent is the most widely used. US6538150 first uses 4-cyano-2-nitrobenzoate as a starting material, uses palladium hydroxide as a catalyst, and undergoes reductive hydrogenation, methanesulfonyl chloride methanesulfonate Acylation followed by diazotization reaction to obtain key intermediates, but in this route, noble metals are used for reductive hydrogenation, which is expensive, and the catalyst cannot be recycled, which also limits industrial production

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