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Pharmaceutical intermediate 2,4-difluorobenzoic acid synthesis method

A technology of difluorobenzoic acid and a synthesis method, which is applied in the field of synthesis of pharmaceutical intermediate 2,4-difluorobenzoic acid, can solve the problems of difficult operation, complicated process, low yield and the like, and achieves shortening reaction time and reducing Intermediate link, the effect of improving the reaction yield

Inactive Publication Date: 2018-10-09
CHENGDU ZHONGHENG HUATIE TECH CO LTD
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  • Abstract
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  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

2,4-Difluorobenzoic acid is generally prepared from m-dinitrobenzene through five steps of reduction, diazotization, fluorination, acylation, and oxidation. The reaction steps of this method are relatively long, and the diazotization reaction requires Low temperature control, difficult operation, low yield and complicated process, therefore, it is necessary to propose a new synthesis method, which has important economic significance for further improving the quality and yield of products and reducing the content of by-products

Method used

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  • Pharmaceutical intermediate 2,4-difluorobenzoic acid synthesis method

Examples

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Effect test

example 1

[0011] In the reaction vessel, add 3 mol of 1,3-dichloro-2-propanol solution with a mass fraction of 60%, 2 mol of 2,4-difluoro-6-bromo-cumene solution with a mass fraction of 90%, and an aqueous solution 600mL, control the stirring speed at 110rpm, increase the solution temperature to 40°C, add 5mol of boron trifluoride butyl ether solution with a mass fraction of 80%, and keep it for 90min. After the reaction is completed, concentrate under reduced pressure, and add 1- 300ml of pentanol solution, filter, adjust the pH of the filtrate to 4, precipitate crystals, filter, recrystallize in 4-methyl-2-pentanone solution with a mass fraction of 91%, dehydrate with anhydrous sodium sulfate dehydrating agent, and obtain the finished product 2 , 290.72g of 4-difluorobenzoic acid, yield 92%.

example 2

[0013] In the reaction vessel, add 3-4mol of 1,3-dichloro-2-propanol solution with a mass fraction of 65%, 2mol of a 91% 2,4-difluoro-6-bromo-isopropylbenzene solution, 700mL aqueous solution, control the stirring speed at 120rpm, increase the solution temperature to 45°C, add 5.5mol of boron trifluoride butyl ether solution with a mass fraction of 82%, and keep it for 100min. After the reaction, concentrate under reduced pressure, and add a mass fraction of 88% 1 - 300ml of pentanol solution, filter, adjust the pH of the filtrate to 4.5, precipitate crystals, filter, recrystallize in 4-methyl-2-pentanone solution with a mass fraction of 93%, dehydrate with phosphorus pentoxide dehydrating agent, and obtain the finished product 2,4-difluorobenzoic acid 297.04g, yield 94%.

example 3

[0015] In the reaction vessel, add 4 mol of 1,3-dichloro-2-propanol solution with a mass fraction of 70%, 2 mol of 2,4-difluoro-6-bromo-cumene solution with a mass fraction of 93%, and an aqueous solution 800mL, control the stirring speed at 130rpm, increase the solution temperature to 50°C, add 6mol of boron trifluoride butyl ether solution with a mass fraction of 85%, and keep it for 110min. After the reaction is completed, concentrate under reduced pressure, and add 1 - 300ml of pentanol solution, filter, adjust the pH of the filtrate to 5, precipitate crystals, filter, recrystallize in 4-methyl-2-pentanone solution with a mass fraction of 95%, dehydrate with anhydrous sodium sulfate dehydrating agent, and obtain the finished product 2,4-difluorobenzoic acid 306.52g, yield 97%.

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Abstract

The invention discloses a pharmaceutical intermediate 2,4-difluorobenzoic acid synthesis method, which mainly comprises: adding 3-4 mol of a 1,3-dichloro-2-propanol solution, 2 mol of a 2,4-difluoro-6-bromo-isopropylbenzene solution and 600-800 ml of an aqueous solution to a reaction container, controlling the stirring speed at 110-130 rpm, heating the solution to a temperature of 40-50 DEG C, adding 5-6 mol of a boron trifluoride-butyl ether solution, maintaining for 90-110 min, carrying out pressure reducing concentration after completing the reaction, adding 300 ml of a 1-pentanol solution,filtering, adjusting the pH value of the filtrate to 4-5, crystallizing, filtering, re-crystallizing in a 4-methyl-2-pentanone solution, and dewatering with a dewatering agent to obtain the finishedproduct 2,4-difluorobenzoic acid.

Description

technical field [0001] The invention relates to a method for synthesizing a pharmaceutical intermediate 2,4-difluorobenzoic acid. Background technique [0002] 2,4-Difluorobenzoic acid is an important intermediate in organic synthesis, mainly used in pharmaceutical intermediates, organic synthesis, organic solvents, and can also be used in dye production, pesticide production and spices. 2,4-Difluorobenzoic acid is generally prepared from m-dinitrobenzene through five steps of reduction, diazotization, fluorination, acylation, and oxidation. The reaction steps of this method are relatively long, and the diazotization reaction requires Low temperature control is difficult to operate, the yield is low, and the process is relatively complicated. Therefore, it is necessary to propose a new synthesis method, which has important economic significance for further improving the quality and yield of the product and reducing the content of by-products. Contents of the invention [...

Claims

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Application Information

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IPC IPC(8): C07C51/16C07C63/70
CPCC07C51/16C07C63/70
Inventor 彭响亮
Owner CHENGDU ZHONGHENG HUATIE TECH CO LTD
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