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Preparation method of phenylurea herbicides

A herbicide and phenylurea technology, which is applied in the field of preparation of 3--1-methoxy-1-methylurea, can solve the problems of low product purity and low yield, and achieves high product purity and high product quality. good quality effect

Inactive Publication Date: 2017-06-13
常州沃腾化工科技有限公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0006] Due to the existence of this by-product, the purity of the product is not high, less than 99%, and the yield is also low, only 83%

Method used

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Examples

Experimental program
Comparison scheme
Effect test

example 1

[0021] (1) Add 10.4 kg of hydroxylamine hydrochloride to 86 kg of water, then add a 32% sodium hydroxide solution to make the pH of the reaction solution 7 to 8, then add 100 kg of toluene, and add 19.8 kg of it dropwise at 12°C P-bromophenyl isocyanate, after the dropwise addition, heat preservation reaction was carried out, and the weight content of p-bromophenyl isocyanate was controlled in HPLC to be less than 0.5%, and 22.4 kg of solids were obtained by filtration;

[0022] (2), adding the solid obtained above into 110 kilograms of water, adding a weight concentration of 32% sodium hydroxide solution to adjust the pH of the reaction solution to be 8 to 10, adding 15 kilograms of dimethyl sulfate dropwise at 20 to 25 ° C, At the same time, add 32% sodium hydroxide solution to control the pH value of the reaction solution to be 8-10, keep the temperature for reaction after the dimethyl sulfate is dripped, and control the weight content of 3-(4-bromophenyl)-1-hydroxyurea in H...

example 2

[0024] (1), 15 kilograms of hydroxylamine sulfate are joined in 95 kilograms of water, then add weight concentration and be 20% potassium hydroxide solution, make reaction solution pH value be 7~8, then add 100 kilograms of 1,2-dichloroethane, 19.8 kg of p-bromophenyl isocyanate was added dropwise at 12°C. After the dropwise addition, the heat preservation reaction was carried out. The weight content of p-bromophenyl isocyanate was controlled in HPLC to be less than 0.5%, and 22.4 kg of solids were obtained by filtration;

[0025] (2), adding the solid obtained above into 112 kilograms of water, adding a weight concentration of 20% potassium hydroxide solution to adjust the pH value of the reaction solution is 8 to 10, and dripping 16 kilograms of dimethyl sulfate at 20 to 25 ° C, At the same time, add 20% potassium hydroxide solution to control the pH value of the reaction solution to be 8-10. After the dimethyl sulfate is dripped, keep it warm and react. The weight content of...

example 3

[0027] (1), 10.4 kg of hydroxylamine hydrochloride was added to 86 kg of water, then potassium carbonate was added to make the pH of the reaction solution 7 to 8, then 120 kg of methylene chloride was added, and 19.8 kg of p-bromophenylisocyanate was added dropwise at 15°C , after the dropwise addition, the insulation reaction was carried out, and the weight content of p-bromophenylisocyanate in the HPLC was less than 0.5%, and 22.5 kilograms of solids were obtained by filtration;

[0028] (2), adding the solid obtained above into 110 kilograms of water, adding a weight concentration of 32% sodium hydroxide solution to adjust the pH of the reaction solution to be 8 to 10, and adding 15.2 kilograms of dimethyl sulfate dropwise at 20 to 25 ° C, At the same time, add 32% sodium hydroxide solution to control the pH value of the reaction solution to be 8-10, keep the temperature for reaction after the dimethyl sulfate is dripped, and control the weight content of 3-(4-bromophenyl)-1...

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Abstract

The invention relates to a preparation method of phenylurea herbicides. The method comprises the following steps of (1) adding hydroxylamine salts into water; then, adding alkali so that the PH value of the reaction solution is 7 to 8; then, adding solvents; dripping 4-bromophenyl isocyanate at 5 to 20 DEG C; after the dripping is completed, performing heat insulation reaction; maintaining the weight content of the 4-bromophenyl isocyanate to be lower than 0.5 percent through HPLC (high performance liquid chromatography) central control; performing filtering to obtain solids; (2) adding the prepared solids into the water; adding alkali to regulate the pH value of the reaction solution to be 8 to 10; dripping dimethyl sulfate at 20 to 25 DEG C; meanwhile, adding alkali to control the pH value of the solution to be 8 to 10; after the dimethyl sulfate is completely dripped, performing heat insulation reaction; maintaining the weight content of 3-(4-bromophenyl)-1-hydroxycarbamide to be lower than 0.5 percent through HPLC central control to reach the reaction completion; performing filtering; obtaining a filter cake, wherein the filter cake is a finished product 3-(4-bromophenyl)-1-methoxyl-1-methylurea. The preparation method has the advantage that no 2-site bromization by-products are generated.

Description

technical field [0001] The invention relates to a preparation method of a phenylurea herbicide, in particular to a preparation method of 3-(4-bromophenyl)-1-methoxy-1-methylurea. Background technique [0002] Bromosulfuron, whose chemical name is 3-(4-bromophenyl)-1-methoxyl-1-methylurea, is a kind of phenylurea herbicide, and the synthetic routes reported in the literature are all from 3- Phenyl-1-methoxy-1-methylurea is obtained by bromination, as reported in Journal of Organic Chemistry USSR (English Translation), vol. 8, p. 1232 - 1238. The synthetic route is: [0003] . [0004] This route uses bromine or other brominating agents to carry out the 4-bromine substitution reaction of the benzene ring, which easily produces the 2-brominated by-product I(a), the structure is as follows: [0005] . [0006] Because the existence of this by-product causes the purity of product not high, is lower than 99%, and yield is also on the low side, only has 83%. Contents of th...

Claims

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Application Information

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IPC IPC(8): C07C273/18C07C275/30
CPCC07C273/1863C07C275/30
Inventor 李红功韦幸红王明峰刘荣孙克周
Owner 常州沃腾化工科技有限公司
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