Synthesis method of insecticide teflubenzuron and intermediate 2,6-difluorobenzamide of insecticide teflubenzuron

Abstract

The invention discloses a synthesis method of an insecticide teflubenzuron and an intermediate 2,6-difluorobenzamide of the insecticide teflubenzuron, belonging to the field of pesticides. The synthesis method comprises the following steps: step 1, preparation of 2,6-dichlorobenzylidene chloride: preparing turbid liquid of dichlorotoluene and phosphorus pentachloride, introducing chlorine gas, layering materials by utilizing a gas-liquid separator, collecting a crude product, and rectifying the crude product to obtain the 2,6-dichlorobenzylidene chloride; and 2, preparation of 2,6-dichlorobenzonitrile: mixing 2,6-dichlorobenzylidene chloride, acetic acid, zinc chloride, hydroxylamine hydrochloride and sodium acetate, carrying out heating for a reflux reaction, conducting cooling, stirring,filtering and drying successively after the reaction is completed so as to obtain 2, 6-dichlorobenzonitrile. By adopting a one-pot method, a reaction route is shortened, total yield is increased to 67.3% from conventional 55.4%, and cost is greatly reduced.

Description

technical field [0001] The invention relates to the field of insecticides, and more specifically relates to a synthesis method of the insecticide furbenuron and its intermediate 2,6-difluorobenzamide. Background technique [0002] Teflubenzuron is a benzoylurea insecticide developed by Celamerck GmbH & Co. in 1984 and launched in 1986. After several acquisitions, it is now owned by BASF. The chemical name of pyriobron is 1-(3,5-dichloro-2,4-difluorophenyl)-3-(2,6-difluorobenzoyl)urea, and the English name is 1-(3,5 -dichloro-2,4-difluorophenyl)-3-(2,6-difluorobenzyl)urea, CAS number: 83121-18-0, molecular formula: C14H6Cl2F4N2O2, molecular weight: 381.11, chemical structural formula: [0003] [0004] At present, the method of synthesizing pyroxanuron is mainly based on 2,6-dichlorotoluene as the starting material, and the intermediate 2,6-difluorobenzamide is obtained through 6 steps of reaction, and then 2 steps are used to obtain pyroxanuron, as shown in the figure be...

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Problems solved by technology

[0007] 1. The process route is long, the yield is low, and the total yield is about 55.4%, resulting in relatively high cost;

[0008] 2. The amount of waste water is very large, mainly because a large amount of waste water is produced during the synthesis process of compound 2→5, which has caused great environmental protection pressure;

[0009] 3. In the first step of chlorination reaction, the chlorination conditions are not easy to control, and there are many isomers and impurities. At present, the general yield of chlorination reaction is 94.5%, and the content is 97%;

[0010] 4. Fluorination reaction, the amount of tar in the synthesis process of compound 6 is relatively large, resulting in low yield and increased solid waste. At present, the general yield of compound 6 is 85%, and the content is 96%;

[0011] 5. In the synthesis process of compound 8, there are currently two methods reported in the literature. One is the phosgene method, which has a better reaction effect, but it is too toxic and poses a great safety hazard; the other is the solid light method, in which solid phosgene is insoluble in solvents. , the two-phase reaction effect is poor;

[0012] 6. During the synthesis process of pyriobron (compound 9), there are many types of impurities, and the content is generally not high, about 96%, which needs to be further refined and purified

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