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Method for preparing 4-aminobenzoic acid from 4-nitrobenzoic acid by catalytic hydrogenation

A technology of nitrobenzoic acid and aminobenzoic acid is applied in chemical instruments and methods, cyanide reaction preparation, preparation of organic compounds, etc., can solve the problems of large pollution, low yield, long process route, etc., and achieves short route , the effect of high yield and low energy consumption

Inactive Publication Date: 2014-09-17
JIANGSU KANGHENG CHEM
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0017] The process route is relatively long, and the yield is relatively low, and the pollution of oxidation and deprotection is relatively large

Method used

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  • Method for preparing 4-aminobenzoic acid from 4-nitrobenzoic acid by catalytic hydrogenation
  • Method for preparing 4-aminobenzoic acid from 4-nitrobenzoic acid by catalytic hydrogenation
  • Method for preparing 4-aminobenzoic acid from 4-nitrobenzoic acid by catalytic hydrogenation

Examples

Experimental program
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Effect test

example 1

[0030] 55.7g of 4-nitrobenzoic acid, 13.3g of sodium hydroxide, and 222.8g of aqueous solution were prepared to form an aqueous solution of sodium salt, which was added to a 1L high-pressure reactor, and then 0.557g of homemade Pd / C catalyst was added to catalyze it, and the hydrogen pressure was controlled to 2-4MPa , the temperature is 60-70 degrees, react until the reaction pressure does not drop, and keep the pressure at this temperature and pressure for 1h. After cooling to room temperature, filter to recover the catalyst, then add 36%-38% hydrochloric acid to acidify to pH 3, cool down to room temperature, and filter to obtain 4-aminobenzoic acid. After drying, 43.9 g of white to off-white solid was obtained, with a yield of 96.2% and a purity (HPLC) of 99.2%.

example 2

[0032] 83.5g of 4-nitrobenzoic acid, 20g of sodium hydroxide, and 334g of aqueous solution were prepared into an aqueous solution of sodium salt, added to a 1L autoclave, and then catalyzed by adding 0.835g of self-made Pd / C catalyst, controlling the hydrogen pressure to 2-4MPa, and the temperature 60-70 degrees, react until the reaction pressure does not drop, and keep the pressure at this temperature and pressure for 1h. After cooling to room temperature, filter to recover the catalyst, then add 36%-38% hydrochloric acid to acidify to pH 3, cool down to room temperature, and filter to obtain 4-aminobenzoic acid. After drying, 66.5 g of white to off-white solid was obtained, with a yield of 97.0% and a purity (HPLC) of 99.3%.

example 3

[0034] 125.25g of 4-nitrobenzoic acid, 30g of sodium hydroxide, and 501g of aqueous solution are prepared into an aqueous solution of sodium salt, added to a 1L high-pressure reactor, and then catalyzed by adding 1.25g of self-made Pd / C catalyst, controlling the hydrogen pressure to 2-4MPa, and the temperature 60-70 degrees, react until the reaction pressure does not drop, and keep the pressure at this temperature and pressure for 1h. After cooling to room temperature, filter to recover the catalyst, then add 36%-38% hydrochloric acid to acidify to pH 3, cool down to room temperature, and filter to obtain 4-aminobenzoic acid. After drying, 99.8 g of white to off-white solid was obtained, with a yield of 97.2% and a purity (HPLC) of 99.2%.

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Abstract

The invention relates to the technical field of organic synthetic chemistry, and particularly relates to a method for preparing a 4-aminobenzoic acid from a 4-nitrobenzoic acid by catalytic hydrogenation. 4-aminobenzoic acid is prepared from a sodium salt water solution of 4-nitrobenzoic acid by low-temperature hydrogenation catalytic reduction and acidification under the catalysis of a noble metal catalyst; the selectivity of 4-nitrobenzoic acid can be up to 100%; the yield of 4-aminobenzoic acid can be up to over 96%; the product is white or off-white power; the purity is more than 99% (high performance liquid chromatography (HPLC)). The method has the advantages of short route, fewer three wastes, low energy consumption, high yield and excellent quality. A water solution is prepared from the 4-nitrobenzoic acid and sodium hydroxide; the water solution of the sodium salt is obtained by hydrogenation reduction under the catalysis of a Pd / C catalyst, and then acidified to obtain the 4-aminobenzoic acid. The selectivity of the 4-nitrobenzoic acid can be up to 100%, the yield of 4-aminobenzoic acid can be up to over 96%, the product is white or off-white power, and the purity is more than 99% (HPLC).

Description

technical field [0001] The invention relates to the technical field of organic synthesis chemistry, in particular to a method for preparing 4-aminobenzoic acid by catalytic hydrogenation of 4-nitrobenzoic acid. Background technique [0002] 4-Aminobenzoic acid is one of the components of folic acid, which is an essential substance for cell growth and division in the body. It is very high in yeast, liver, bran, and malt. Mainly used as dyes and pharmaceutical intermediates. It is used in the production of reactive red M-80, M-10B, reactive red violet X-2R and other dyes and in the preparation of cyanobenzoic acid to produce p-carboxybenzylamine. P-aminobenzoic acid can be used as a sunscreen, and its derivative, octyl p-dimethylcarbamate, is an excellent sunscreen. [0003] Currently 4-aminobenzoic acid has the following three routes: [0004] 1: 4-Nitrobenzoic Acid Reduction Obtained [0005] At present, the most widely used reduction method in industry is iron powde...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07C227/04C07C227/18C07C229/60
Inventor 邱志刚雍成松
Owner JIANGSU KANGHENG CHEM
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