Method for preparing pyrogallic acid from gallic acid in high temperature liquid state water medium by catalyst-free decarboxylating

A technology of pyrogallic acid and high-temperature liquid water, which is applied in chemical instruments and methods, preparation of organic compounds, organic chemistry, etc., can solve the problems of shortening the service life of equipment, serious environmental pollution, and low proportion of analytical grade products, and achieves The effect of high raw material utilization rate, simple reaction process and high product yield

Inactive Publication Date: 2008-03-19
ZHEJIANG UNIV
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0008] However, the vacuum decarboxylation method mainly has the following disadvantages: uneven heating of materials, waste of energy, shortened equipment life cycle, catalysts are often used in the process, serious environmental pollution, and the proportion of analytical grade products in the products is relatively low, mostly chemically pure or industrial product

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  • Method for preparing pyrogallic acid from gallic acid in high temperature liquid state water medium by catalyst-free decarboxylating
  • Method for preparing pyrogallic acid from gallic acid in high temperature liquid state water medium by catalyst-free decarboxylating

Examples

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Effect test

Embodiment 1

[0026] Add 267g of deionized water and 133g of gallic acid into a 500mL intermittent high-pressure reactor, the mass ratio of deionized water to gallic acid is 2:1, start stirring, heat up to boiling under normal pressure, open the exhaust valve for 3min, and use steam Exclude the air in the kettle; close the exhaust valve, continue to heat up to 190 ° C for 3.5 hours; the reaction product is cooled to room temperature and extracted with ethyl formate, and the extract is evaporated to remove the organic solvent to obtain the crude product of pyrogallic acid. The crude product is deionized water Dissolved, decolorized by activated carbon, recrystallized, and vacuum dried to obtain 107.4 g of pyrogallic acid product, the product was analyzed by HPLC with a purity of 99.3% (wt%) and a yield of 80.8%.

Embodiment 2

[0028] Add 267g of deionized water and 133g of gallic acid into a 500mL intermittent high-pressure reactor, the mass ratio of deionized water and gallic acid is 2:1, start stirring, heat up to boiling under normal pressure, open the exhaust valve for 4min, and use steam Exclude the air in the kettle; close the exhaust valve, continue to heat up to 210 ° C for 2.5 hours; the reaction product is cooled to room temperature and extracted with ethyl acetate, and the extract is evaporated to remove the organic solvent to obtain the crude product of pyrogallic acid. The crude product is deionized water Dissolved, decolorized with activated carbon, recrystallized, and vacuum dried to obtain 108.8 g of pyrogallic acid product, the product was analyzed by HPLC with a purity of 99.4% (wt%) and a yield of 81.8%.

Embodiment 3

[0030] Add 286g of deionized water and 114g of gallic acid into a 500mL intermittent high-pressure reactor, the mass ratio of deionized water and gallic acid is 2.5:1, start stirring, heat up to boiling under normal pressure, open the exhaust valve for 2min, and use steam Exclude the air in the kettle; close the exhaust valve, continue to heat up to 180 ° C for 4 hours; the reaction product is cooled to room temperature and extracted with methyl acetate, and the extract is evaporated to remove the organic solvent to obtain crude pyrogallic acid, which is dissolved in deionized water , after activated carbon decolorization, recrystallization, and vacuum drying, 99.4g of pyrogallic acid product was obtained, and the product was analyzed by HPLC with a purity of 99.6% (wt%) and a yield of 87.2%.

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Abstract

The invention discloses a method by which the gallic acid in high-temperature liquid water medium is non-catalystically decarboxylated to prepare pyrogallic acid. The method includes three steps; firstly, deionized water and gallic acid are added into a high-pressure reaction kettle, the mass ratio between the deionized water and the gallic acid is 2 : 1 to 6 : 1, stiring is started, temperature under the normal pressure is raised until boiling, and an exhaust valve is opened for two to five minutes; secondly, the exhaust valve is closed, the temperature is continuously raised to 180 DEG C to 250 DEG C, and reaction lasts half to four hours; thirdly, after being cooled down until room temperature, a reaction product is extracted by organic solvent, crude pyrogallic acid is produced after the organic solvent is evaporated from extract, and after the crude pyrogallic acid resolved in deionized water is decoloured, recrystallized and undergoes vacuum drying, the pyrogallic acid product is produced. The invention has the advantages of simple reaction process, high utilization ratio of materials, high product yield, environment-friendly production procedure and high quality of pyrogallic acid product, and as a result, the invention resolves the major problem that the current preparation of pyrogallic acid by catalyzing acid and alkali pollutes envrionment.

Description

technical field [0001] The invention relates to a method for preparing pyrogallic acid by non-catalytic decarboxylation of gallic acid in a high-temperature liquid water medium. Background technique [0002] Pyrogallic acid (pyrogallic acid, CAS: 87-66-1), also known as pyrogallol, pyrogallol, chemical name 1,2,3-trihydroxybenzene, is an important chemical product, widely used Used in chemical analysis, photographic development, fuel, paint, food, pharmaceuticals, electronic materials, pesticides and other industries. [0003] At present, the preparation methods of pyrogallic acid include one-step method, indirect method and chemical synthesis method, etc., wherein the indirect method is widely used in industry, and there is no report on industrial production of chemical synthesis method and one-step method. [0004] The chemical synthesis method generally uses cyclohexanone, cyclohexanol and resorcinol etc. as raw materials to synthesize pyrogallic acid, wherein the repres...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07C39/10C07C37/50
Inventor 吕秀阳吕丽丽
Owner ZHEJIANG UNIV
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