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Method for preparing isonicotinic acid by non-catalytic hydrolyzing isonicotinonitrile in near-critical water medium

A near-critical water and catalytic hydrolysis technology, applied in the field of carboxylic acids, can solve problems such as complex process, increased equipment investment, environmental pollution, etc., and achieve the effects of solving pollution problems, high product purity and yield, and simple reaction process.

Inactive Publication Date: 2009-06-24
ZHEJIANG UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The obvious disadvantage of this process is that the process is complicated, the equipment investment is increased, the reaction process uses a large amount of strong alkali catalysts to cause serious environmental pollution, serious overoxidation, and the preparation, selection and recovery of metal catalysts are not yet perfect.

Method used

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  • Method for preparing isonicotinic acid by non-catalytic hydrolyzing isonicotinonitrile in near-critical water medium
  • Method for preparing isonicotinic acid by non-catalytic hydrolyzing isonicotinonitrile in near-critical water medium

Examples

Experimental program
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Effect test

Embodiment 1

[0027] Add 300g of deionized water and 150g of isonicotonitrile (the mass ratio of deionized water to isoniazid is 2:1) in a 500mL intermittent autoclave, start stirring, heat up to boiling under normal pressure, open the exhaust valve for 5min, Use water vapor to remove the air in the kettle; close the exhaust valve, continue to heat up to 200°C for 600 minutes; add HCl solution to adjust the pH value to 3-4 after the reaction product is cooled, and obtain crude isonicotinic acid after crystallization. The crude isonicotinic acid product was dissolved in hot water, decolorized by activated carbon, secondary crystallized, and dried in vacuum to obtain 133.5 g of isonicotinic acid product. The purity of the product was 98.1% (wt%) analyzed by HPLC, and the yield was 73.8%.

Embodiment 2

[0029] Add 360g of deionized water and 120g of isonicotonitrile (mass ratio of deionized water to isonicotonitrile is 3:1) in a 500mL intermittent autoclave, start stirring, heat up to boiling under normal pressure, open the exhaust valve for 4min, Use steam to remove the air in the kettle; close the exhaust valve, continue to heat up to 210 ° C for 550 minutes; add H after the reaction product is cooled 2 SO 4 The pH value of the solution was adjusted to 3-4, and the crude product of isonicotinic acid was obtained after crystallization. The crude isonicotinic acid product was dissolved in hot water, decolorized by activated carbon, secondary crystallized, and dried in vacuum to obtain 110.1 g of isonicotinic acid product, which was analyzed by HPLC with a purity of 98.2% (wt%) and a yield of 76.2%.

Embodiment 3

[0031] Add 320g of deionized water and 80g of isonicotonitrile (mass ratio of deionized water to isonicotonitrile is 4:1) in a 500mL intermittent autoclave, start stirring, heat up to boiling under normal pressure, open the exhaust valve for 3min, Use water vapor to remove the air in the kettle; close the exhaust valve, continue to heat up to 220°C and react for 500 minutes; add HCl solution to adjust the pH value to 3-4 after the reaction product is cooled, and obtain crude isonicotinic acid after crystallization. The crude isonicotinic acid product was dissolved in hot water, decolorized by activated carbon, secondary crystallized, and vacuum dried to obtain 76.0 g of isonicotinic acid product. The purity of the product was 98.8% (wt%) analyzed by HPLC, and the yield was 79.3%.

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Abstract

The invention discloses a method for preparing isonicotinic acid without catalytic hydrolysis of isonicotinic nitrile in near-critical water medium. The method comprises the following steps: 1) deionized water and the isonicotinic nitrile with the mass ratio of 2 to 1 to 8 to 1 are added into a high-pressure reactor kettle and stirred. Under normal pressure, the temperature is raised until the liquid boils. An exhaust valve is opened for 2-5min; 2) the exhaust valve is closed, and the temperature is continuously raised to 200-300 DEG C for the hydrolysis for 30-600min; 3) hydrolytic products are cooled, the pH value is regulated to 3-4, and after the crystallization, crude isonicotinic acid is obtained; 4) the crude isonicotinic acid is dissolved in hot water and after decolorizing by activated carbon, secondary crystallization and vacuum drying, the isonicotinic acid products are obtained. During the reaction, no catalysts are required to be added, and the hard problem of pollution caused by acid and alkaline catalytic hydrolysis is solved. The method has the advantages of simple and green process and high purity and yield of products.

Description

technical field [0001] The invention relates to carboxylic acids, in particular to a method for preparing isonicotinic acid by non-catalytic hydrolysis of isonicotinonitrile in a near-critical water medium. Background technique [0002] Isonicotinic acid (Isonicotinic acid, 4-Picolinic acid, Pyridine-4-carboxylic acid, CAS No.: 55-22-1), also known as isonicotinic acid, chemical name pyridine-4-carboxylic acid, molecular formula C 6 h 5 NO 2 , the structural formula is: White needle-like crystalline powder, odorless; melting point 319°C, sublimation at 260°C (2kPa); soluble in hot water, slightly soluble in cold water, almost insoluble in benzene, ether, etc. The substance is an amphoteric compound, soluble in both acids and bases, reacting with acids to form pyridinium salts, and reacting with bases to form carboxylate salts. Pyridinecarboxylic acid exists as internal salt in aqueous solution, that is, in the form of zwitterions. [0003] Isonicotinic acid is a widely...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07D213/803
Inventor 吕秀阳任浩明
Owner ZHEJIANG UNIV
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