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Method for preparing 4-aminobenzoic acid by catalytic hydrogenation

An aminobenzoic acid, catalytic hydrogenation technology, applied in chemical instruments and methods, preparation of cyanide reaction, preparation of organic compounds, etc., can solve the problems of long process route, low significance of industrialized production, etc., and achieve perfect process , the effect of high production efficiency and low energy consumption

Inactive Publication Date: 2015-02-04
江苏恒祥化学股份有限公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0013] The process route is relatively long, and the significance of industrial production is not great

Method used

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

Examples

Experimental program
Comparison scheme
Effect test

example 1

[0024] 50g 4-nitrobenzoic acid and 12g sodium hydroxide, 150g water are mixed with the aqueous solution of 4-nitrobenzoic acid sodium salt, join in the 1L autoclave, and add 0.5g 5%Pd / C, after nitrogen replacement three times, Hydrogen was replaced twice, the pressure was added to 2 MPa, the temperature was controlled at 60-70 degrees, and the reaction was carried out until the pressure did not drop substantially. After about 2 hours, the catalyst was recovered. The resulting reaction solution was acidified with concentrated hydrochloric acid to pH 3, filtered and washed with water to obtain 4-aminobenzoic acid as a white solid, and 38.9 g of the product was obtained after drying, with a yield of 95% and a purity of 99.5% (HPLC).

[0025]

example 2

[0027] 100g 4-nitrobenzoic acid and 24g sodium hydroxide, 300g water are mixed with the aqueous solution of 4-nitrobenzoic acid sodium salt, join in the 1L autoclave, and add 1.0g 5%Pd / C, after nitrogen replacement three times, Hydrogen was replaced twice, the pressure was added to 2 MPa, the temperature was controlled at 60-70 degrees, and the reaction was carried out until the pressure did not drop substantially. After about 2 hours, the catalyst was recovered. The resulting reaction solution was acidified to pH 3 with concentrated hydrochloric acid, filtered and washed with water to obtain 4-aminobenzoic acid as a white solid, and 78.8 g of the product was obtained after drying, with a yield of 96.1% and a purity of 99.4% (HPLC).

[0028]

example 3

[0030] 150g 4-nitrobenzoic acid and 36g sodium hydroxide, 450g water are mixed with the aqueous solution of 4-nitrobenzoic acid sodium salt, join in the 1L autoclave, and add 1.5g 5%Pd / C, after nitrogen replacement three times, Hydrogen was replaced twice, the pressure was added to 2 MPa, the temperature was controlled at 60-70 degrees, and the reaction was carried out until the pressure did not drop substantially. After about 2 hours, the catalyst was recovered. The resulting reaction solution was acidified with concentrated hydrochloric acid to pH 3, filtered and washed with water to obtain 4-aminobenzoic acid as a white solid, and 118.5 g of the product was obtained after drying, with a yield of 96.3% and a purity of 99.6% (HPLC).

[0031]

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Abstract

The invention relates to the field of production of 4-aminobenzoic acid and specifically relates to a method for preparing 4-aminobenzoic acid by catalytic hydrogenation. The method comprises the following steps: preparing a water solution of a neutral sodium salt from 4-nitrobenzoic acid and the equal molar amount of an alkali (sodium hydroxide) for preparing 4-nitrobenzoate by using 3 times the mass of solvent water the mass of which is 3 times that of 4-nitrobenzoic acid and alkali, performing hydrogenation reduction for 2h by taking 5% Pd / C as a catalyst, controlling the pressure of hydrogen to 1-2MPa and controlling the temperature to 60-70 degrees till the pressure is not reduced basically to obtain the water solution of the sodium salt, further acidifying and filtering to obtain white 4-aminobenzoic acid, wherein the yield is above 95% and the purity is above 99%. The method provided by the invention has the advantages of perfect process, low energy consumption, short reaction period and no corrosion and is safe to operate, and the environment-friendly process for preparing 4-aminobenzoic acid by taking 4-nitrobenzoic acid as a raw material and performing catalytic hydrogenation at low temperature and low pressure is high in production efficiency.

Description

technical field [0001] The invention relates to the field of 4-aminobenzoic acid production, in particular to a method for preparing 4-aminobenzoic acid by catalytic hydrogenation. Background technique [0002] P-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. [0003] Mainly used in 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. [0004] The synthetic method of this compound has following several at present: [0005] 1: Obtained by reducing iron powder with p-nitrobenzoic acid as raw material [0006] [0007] This process is the main route...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07C227/04C07C229/60
Inventor 邱志刚
Owner 江苏恒祥化学股份有限公司
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