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Method for preparing 2,4,5- trifluoro-3-methyl benzoic acid

A technology of methyl benzoic acid and trifluorobenzoic acid, which is applied in two fields, can solve the problems of high price and achieve the effects of low cost, high product yield and reasonable design

Active Publication Date: 2012-07-04
锦州三溢科技有限公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Vladimir Beylin, David C. Boyles, et al. (Org. Process Res. Dev., 2007, 11 (3), 441-449 ) synthesized this compound without using a protective agent, but using the expensive reagent hexamethyldisilica Lithium amide

Method used

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  • Method for preparing 2,4,5- trifluoro-3-methyl benzoic acid
  • Method for preparing 2,4,5- trifluoro-3-methyl benzoic acid
  • Method for preparing 2,4,5- trifluoro-3-methyl benzoic acid

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Experimental program
Comparison scheme
Effect test

Embodiment 1

[0015] Embodiment 1, a kind of preparation method of 2,4,5-trifluoro-3-methylbenzoic acid, its steps are as follows:

[0016] (1) 2,4,5-trifluorobenzoic acid is reacted with a mixed base in an organic solvent to obtain a metal salt with both carboxyl and C3 positions substituted; the reaction temperature is -80°C; 2,4,5-trifluorobenzoic acid The mass ratio of benzoic acid and mixed base is 1:1.5; Described mixed base is made of n-butyl lithium, a kind of in tert-butyl lithium or isopropyl lithium, potassium tert-butoxide, sodium methylate or potassium methylate One, and a mixed composition of 2,2,6,6-tetramethylpiperidine, diisopropylamine, tetramethylethylenediamine, and 2-mercaptobenzothiazole, and the three in sequence The mass ratio is 1:0.2:5; the organic solvent is alcohol ether solvent;

[0017] (2) React the metal salt with a methylating reagent at a reaction temperature of -80°C; a substitution reaction occurs at the C3 position of the benzene ring to obtain 2,4,5-tr...

Embodiment 2

[0018] Embodiment 2, a kind of preparation method of 2,4,5-trifluoro-3-methylbenzoic acid, its steps are as follows:

[0019] (1) 2,4,5-trifluorobenzoic acid reacts with a mixed base in an organic solvent to obtain a metal salt with both carboxyl and C3 positions substituted; the reaction temperature is 20°C; 2,4,5-trifluorobenzene The mass ratio of formic acid to the mixed base is 1:3; the mixed base is composed of one of n-butyl lithium, tert-butyl lithium or isopropyl lithium, one of potassium tert-butoxide, sodium methylate or potassium methylate species, and a mixture of 2,2,6,6-tetramethylpiperidine, diisopropylamine, tetramethylethylenediamine, and 2-mercaptobenzothiazole, the mass of the three in sequence The ratio is 1: 5: 0.2; the organic solvent is alcohol ether solvent;

[0020] (2) React the metal salt with a methylating reagent at a reaction temperature of 20°C; a substitution reaction occurs at the C3 position of the benzene ring to obtain 2,4,5-trifluoro-3-met...

Embodiment 3

[0021] Embodiment 3, a kind of preparation method of 2,4,5-trifluoro-3-methylbenzoic acid, its steps are as follows:

[0022] (1) 2,4,5-trifluorobenzoic acid reacts with a mixed base in an organic solvent to obtain a metal salt with both carboxyl and C3 positions substituted; the reaction temperature is -20°C; 2,4,5-trifluorobenzoic acid The mass ratio of benzoic acid and mixed base is 1:2.5; Described mixed base is made of n-butyl lithium, a kind of in tert-butyl lithium or isopropyl lithium, potassium tert-butoxide, sodium methylate or potassium methylate One, and a mixed composition of 2,2,6,6-tetramethylpiperidine, diisopropylamine, tetramethylethylenediamine, and 2-mercaptobenzothiazole, and the three in sequence The mass ratio is 1:1:1; the organic solvent is alcohol ether solvent;

[0023] (2) React the metal salt with a methylating reagent at a reaction temperature of -20°C; a substitution reaction occurs at the C3 position of the benzene ring to obtain 2,4,5-trifluor...

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Abstract

The invention provides a method for preparing 2,4,5- trifluoro-3-methyl benzoic acid. The method is characterized in that 2,4,5-trifluorobenzoic acid reacts with mixed alkali under the condition of an organic solvent so as to obtain metal salt, of which the carboxylic group and the C3 site are substituted; mixed alkali comprises one of n-butyllithium or tert-butyllithium or lithium isopropoxide, one of potassium tert-butoxide or sodium methylate or potassium methoxide and one of 2,2,6,6-tetramethyl-piperidine or diisopropylamine or tetramethyl ethylenediamine or 2-hydrosulfuryl benzothiazole in a mixing manner, and organic solvent is alcohol ether solvent; metal salt reacts with methylating agents, and a substitution reaction is performed at the benzene ring C3 site so as to obtain 2,4,5- trifluoro-3-methyl benzoic acid; and the reaction temperature ranges from subzero 80 to 20 DEG C. The method has the advantages of high reaction temperature and low cost, and is easy for industrialized production.

Description

technical field [0001] The invention relates to the field of organic chemical synthesis, in particular to a preparation method of 2,4,5-trifluoro-3-methylbenzoic acid. Background technique [0002] Fluorine-containing aromatic compounds are mainly used as intermediates of physiologically active compounds such as pesticides and medicines, and have good thermal stability and high fat solubility. For example, used as herbicides, fungicides, anti-tumor drug functional dyes, etc. Because fluorine itself is highly active, it is difficult to control in the reaction, especially when introducing molecules at specific positions, so the preparation of fluorine-containing organic compounds is still a very challenging field. [0003] 2,4,5-Trifluoro-3-methylbenzoic acid is an increasingly versatile intermediate and is a commonly used pharmaceutical intermediate. The method of replacing the methyl group on the benzene ring is the Grignard reagent synthesis method, which is a Grignard r...

Claims

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Application Information

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IPC IPC(8): C07C63/70C07C51/353
Inventor 陈卫东
Owner 锦州三溢科技有限公司
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