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A kind of synthetic method of 2-chloro-4-fluoro-5-nitrobenzoic acid

A technology of nitrobenzoic acid and fluorobenzoic acid, applied in chemical instruments and methods, preparation of organic compounds, organic chemistry, etc., can solve problems such as low total yield, achieve high yield, complete reaction, and mild reaction conditions Effect

Active Publication Date: 2019-03-01
山东腾滨科技有限公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0012] This route can not avoid the production of isomers of formula (II), and requires two steps of reaction, the overall yield is not high

Method used

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Examples

Experimental program
Comparison scheme
Effect test

example 1

[0020] Example 1. Preparation of catalyst: Take 10 grams of cobalt chloride (hydrated) and 50 grams of anhydrous zirconium chloride, dissolve them in 500ml of absolute ethanol at room temperature, and then evaporate the ethanol to dryness on a rotary evaporator below 50°C under reduced pressure , and the obtained solid is sealed and stored.

example 2

[0021] Example 2, put 50 grams of concentrated sulfuric acid in the reaction flask, 0.8 grams of the catalyst obtained in Example 1, add 10 grams of 2-chloro-4 fluorobenzoic acid in batches, stir at 25 ° C for 1 hour, cool to zero in an ice bath, add dropwise 5 grams of fuming nitric acid, control the reaction temperature at -5 ~ 8°C, stir at -5°C ~ 8°C for 1 hour after the dropwise addition, the content of 2-chloro-4fluorobenzoic acid in the middle control is less than 0.5% and the reaction is completed; under stirring Slowly pour the reaction solution into 80 grams of crushed ice, filter, rinse the filter cake with 30 grams of ice water, and dry it with air at 65°C to obtain a off-white solid product 2-chloro-4-fluoro-5-nitrobenzoic acid 12.0 grams, with a yield of 97.1%, a purity of 97.2%, and a weight content of the isomer compound of formula (II) of 1.1%.

example 3

[0022] Example 3, drop 40 grams of concentrated sulfuric acid into the reaction flask, 1.5 grams of the catalyst obtained in Example 1, add 10 grams of 2-chloro-4-fluorobenzoic acid in batches, stir at 25 ° C for 1 hour, and cool to 10 ° C in an ice bath. Add 6 grams of fuming nitric acid dropwise, control the reaction temperature at 10-20°C, and stir at 10°C-20°C for 1 hour after the dropwise addition, and the content of 2-chloro-4fluorobenzoic acid in the center is less than 0.5%. Slowly pour the reaction solution into 80 grams of crushed ice, filter, rinse the filter cake with 30 grams of ice water, and dry it with blast at 65°C to obtain the off-white solid product 2-chloro-4-fluoro-5-nitrobenzoic acid 11.6 grams, the yield is 96.6%, the purity is 97.6%, and the weight content of the isomer compound of formula (II) is 0.9%.

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Abstract

The invention relates to a synthesis method of 2-chloride-4-fluoride-5-nitrobenzoic acid. The synthesis method is characterized by including the steps: adding 2-chloride-4 fluorobenzoic acid and a catalyst into concentrated sulfuric acid; dripping nitrosonitric acid at the temperature ranging from -10 DEG C to 30 DEG C; pouring reaction solution into crushed ice under stirring after reaction; filtering mixture; rinsing filter cakes by the aid of ice water, and drying the rinsed filter cakes to obtain white finished 2-chloride-4-fluoride-5-nitrobenzoic acid. The synthesis method has the advantages that the purity of finished products can be improved.

Description

technical field [0001] The invention relates to a method for synthesizing an intermediate of the pesticide saflufenacil, in particular to a method for synthesizing 2-chloro-4-fluoro-5-nitrobenzoic acid. Background technique [0002] 2-Chloro-4-fluoro-5-nitrobenzoic acid of the following formula (I) is an important intermediate of the pesticide saflufenacil, [0003] . [0004] Documents WO87 / 07602, EP0863142, WO01 / 83459 report that their synthetic routes are all obtained from 2-chloro-4-fluorobenzoic acid through nitration reaction with mixed acid (sulfuric acid + nitric acid). [0005] . [0006] East China University of Science and Technology Tang Aping's master thesis "Study on the Synthesis of Saflufenacil" reported that the yield of 2-chloro-4-fluoro-5-nitrobenzoic acid synthesized by this route reached 96%. [0007] After carrying out experiments according to the methods reported in the above literatures, we found that direct nitration with mixed acid will produ...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C07C201/10C07C205/58B01J27/135
CPCB01J27/135C07C201/10C07C205/58
Inventor 孙富强韦幸红李大娟孙克周陈红元
Owner 山东腾滨科技有限公司
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