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Method for preparing p-aminobenzoic acid by reducing p-nitrobenzoic acid by utilizing ammonium thiosulfate

A technology of p-nitrobenzoic acid and p-aminobenzoic acid, applied in chemical instruments and methods, cyanide reaction preparation, organic compound preparation, etc., can solve the problem of low cost, unfavorable operators and environment, reduction Low efficiency and other issues, to achieve the effect of low production cost, environmental friendliness and less pollution

Inactive Publication Date: 2014-08-13
苏州久王环保科技股份有限公司 +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0005]Among the various methods of nitro reduction, the iron powder reduction method has always been the most widely used traditional method, but the iron filings reduction method will produce a large amount of iron sludge , seriously pollute the environment; the zinc powder reduction method is also widely applicable, but the zinc salt waste residue produced in production still needs to be treated separately; the cost of the alkali sulfide reduction method is low, but its reduction efficiency is not high, and harmful gases will be released during the reaction , which is not good for the operator and the environment
Therefore, the above methods are all limited because they will cause serious environmental pollution, prompting people to explore new and more environmentally and economically beneficial production methods

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0023] In a four-neck flask, add 1g of compound (1): p-nitrobenzoic acid, then add 20ml of ethanol and 10ml of water, start heating and stirring, the heating temperature is 80°C; after it is completely dissolved, add 6g of ( NH 4 ) 2 S 2 o 3 , to make it completely dissolved, and reflux reaction at 80°C for 4 hours; after 4 hours, the reaction stopped, and naturally cooled to room temperature, white crystals precipitated, and the precipitated crystals were filtered by suction, and compound (2) was obtained after complete drying: p-aminobenzoic acid , weighed 0.72g, and the yield was about 87.7%.

Embodiment 2

[0025] In a four-neck flask, add 1g of compound (1): p-nitrobenzoic acid, then add 80ml of ethanol and 40ml of water, start heating and stirring at 80°C; after all of it is dissolved, add 6g of ( NH 4 ) 2 S 2 o 3 , to make it completely dissolved, and reflux reaction at 80°C for 4 hours; after 4 hours, the reaction stopped, and naturally cooled to room temperature, white crystals precipitated, and the precipitated crystals were filtered by suction, and compound (2) was obtained after complete drying: p-aminobenzoic acid . The weighed was 0.7 g and the yield was about 85.3%.

Embodiment 3

[0027] In the four-necked bottle, add 1g of compound (1): p-nitrobenzoic acid, then add 200ml of ethanol and 80ml of water, start heating and stirring, the heating temperature is 80°C; after it is completely dissolved, add 6g of ( NH 4 ) 2 S 2 o 3 , to make it completely dissolved, and reflux reaction at 80°C for 4 hours; after 4 hours, the reaction stopped, and naturally cooled to room temperature, white crystals precipitated, and the precipitated crystals were filtered by suction, and compound (2) was obtained after complete drying: p-aminobenzoic acid , weighed 0.66g, and the yield was about 80.4%.

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Abstract

The invention discloses a method for preparing p-aminobenzoic acid by reducing p-nitrobenzoic acid by utilizing ammonium thiosulfate. The method comprises the following steps: putting p-nitrobenzoic acid into a mixed solution of an organic solvent and water and stirring p-nitrobenzoic acid until p-nitrobenzoic acid is totally dissolved; adding ammonium thiosulfate and carrying out reflux reaction after heating and stirring; naturally cooling the reactant to the room temperature after reaction is stopped, precipitating a solid and leaching and drying the precipitated solid, thus obtaining the final product, namely p-aminobenzoic acid. The method is lower in production cost, is convenient and safe to operate, is environment-friendly, is simple in equipment and is suitable for continuous production.

Description

technical field [0001] The invention relates to a method for preparing p-aminobenzoic acid by reducing p-nitrobenzoic acid with ammonium thiosulfate. Background technique [0002] In the process of desulfurization and decyanation of coking gas purification, waste liquid will be produced. The inorganic salt ammonium thiosulfate recovered through the harmless treatment of waste liquid has a wide range of uses. It can be used as a fixer for photography, for plating Silver electroplating solution, metal cleaning agent, reducing agent, complexing agent, aluminum-magnesium alloy casting protection agent and chemical reagent. [0003] p-Nitrobenzoic acid is an intermediate in organic synthesis of medicines, dyes, veterinary drugs, photosensitive materials, etc. It is used in the production of procaine hydrochloride, procainamine hydrochloride, p-aminomethylbenzoic acid, folic acid, benzo Caine, cough, cephalosporin v, p-aminobenzoyl glutamic acid, Bernier, and the production of re...

Claims

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Application Information

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IPC IPC(8): C07C229/60C07C227/04
Inventor 张超智
Owner 苏州久王环保科技股份有限公司
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