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Method for preparing 2,3,4-trimethoxybenzoic acid

A technology of trimethoxybenzoic acid and raw materials, applied in the field of pharmaceutical intermediates 2, can solve problems such as large pollution

Inactive Publication Date: 2008-09-17
南京龙源天然多酚合成厂
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0003] It has been reported abroad that 2,3,4-trihydroxybenzoic acid is used as a raw material, and dimethyl sulfate is used to obtain 2,3,4-trimethoxybenzoic acid through methylation. The yield of this method is only 70%-80%. And dimethyl sulfate is a highly toxic chemical, causing great pollution

Method used

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  • Method for preparing 2,3,4-trimethoxybenzoic acid

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0018] ① Dissolve 16.5g of sodium hydroxide in 700g of water, stir to dissolve;

[0019] ②Add 65g of 2,3,4-trimethoxybenzaldehyde to the above alkaline solution, raise the temperature to 50°C, and stir to form an oil-water two-phase solution system;

[0020] ③Add 2g of tetrabutylammonium bromide to the above solution;

[0021] ④ Under stirring, add 39 g of potassium permanganate to it, and control the temperature to 45-45°C. After reacting for 2 hours, the temperature was raised to 55-60°C and reacted for 1 hour.

[0022] ⑤ Vacuum filtration, and wash the filter cake with 50×3 ml of water, and combine the filtrate and washing liquid.

[0023] ⑥ Adjust the pH to 7-8 with 3-5g 35% hydrochloric acid. Add 2g of activated carbon and 2g of sodium bisulfite, heat up to 80-85°C, decolorize for 15 minutes, and vacuum filter;

[0024] ⑦Take the filtrate, add 70g 35% hydrochloric acid, adjust the pH to 1-2, at this time a large amount of white precipitate is formed, stir and cool to 5-10°C, ...

Embodiment 2

[0027] ① Dissolve 38g potassium carbonate in 700g water and stir to dissolve;

[0028] ②Add 65g of 2,3,4-trimethoxybenzaldehyde to the above alkaline solution, raise the temperature to 50°C, and stir to form an oil-water two-phase solution system;

[0029] ③Add 2g of tetrabutylammonium chloride to the above solution;

[0030] ④ Under stirring, add 39 g of potassium permanganate to it, and control the temperature to 45-45°C. After reacting for 2 hours, the temperature is raised to 55-60°C and reacted for 1 hour;

[0031] ⑤ Vacuum filtration, and wash the filter cake with 50×3 ml of water, and combine the filtrate and washing liquid;

[0032] ⑥ Adjust the pH to 7-8 with 3-5g 35% hydrochloric acid. Add 2g of activated carbon, 2g of sodium bisulfite, heat to 80-85°C, decolorize for 15 minutes, vacuum filter, and wash the precipitate with 50×3 ml of water;

[0033] ⑦Take the filtrate and add 70g 35% hydrochloric acid to adjust the pH to 1-2. At this time, a large amount of white precip...

Embodiment 3

[0036] ① Dissolve 29g of sodium carbonate in 700g of water and stir to dissolve;

[0037] ②Add 65g of 2,3,4-trimethoxybenzaldehyde to the above alkaline solution, raise the temperature to 50°C, and stir to form an oil-water two-phase solution system;

[0038] ③Add 2g of benzyltriethylammonium chloride to the above solution;

[0039] ④ Under stirring, add 39 g of potassium permanganate to it, and control the temperature to 45-45°C. After reacting for 2 hours, the temperature is raised to 55-60°C and reacted for 1 hour;

[0040] ⑤ Vacuum filtration, and wash the filter cake with 50×3 ml of water, and combine the filtrate and washing liquid;

[0041] ⑥ Adjust the pH to 7-8 with 3-5g 35% hydrochloric acid. Add 2g of activated carbon and 2g of sodium bisulfite, heat up to 80-85°C, decolorize for 15 minutes, and vacuum filter;

[0042] ⑦Take the filtrate and add 70g 35% hydrochloric acid to adjust the pH to 1-2. At this time, a large amount of white precipitate is formed, stir and cool ...

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Abstract

The invention relates to a method of preparing 2, 3, 4-trimethoxybenzoic acid. 2, 3, 4-trimethoxy benzaldehyde which is used as raw material is mixed with alkaline solution and stirred to form two-phase solution; a phase transfer catalyst that is tetrabutyl ammonium chloride or tetrabutyl ammonium bromide or benzyl triethyl ammonium chloride is added, and potassium permanganate is added for reacting for 2 to 4 hours; the mixed solution is processed through vacuum drawing and filtering, and the pH value of filter liquor is adjusted to reach 7 to 9 by using hydrochloric acid or sulphuric acid; active carbon is added and stirred; the mixed solution is decoloured for 10 to 30 minutes under the temperature ranging from 80 to 95 DEG C, and is filtered to remove the active carbon; the filter liquor is added with acid until which the white 2, 3, 4-trimethoxybenzoic acid is completely precipitated and separated out; after vacuum filtration, filter mass is processed through decompression and vacuum drying under the conditions that the pressure ranges from minus 0.08 to 0.09 MPa and the temperature ranges from 40 to 80 DEG C, so that the 2, 3, 4-trimethoxy benzaldehyde products are obtained. The method adopts the phase transfer catalysis technology, enhances the oxidation speed and effect, controls the depth of the oxidation reaction to prevent the 2, 3, 4-trimethoxy benzaldehyde from being further oxidized to form quinine, thereby obtaining the high-purity 2, 3, 4-trimethoxy benzaldehyde. The product yield and the purity are high, and the requirement of the pharmaceutical intermediate can be satisfied.

Description

Technical field [0001] The invention relates to a preparation method of medical intermediate 2,3,4-trimethoxybenzoic acid. Background technique [0002] As a pharmaceutical intermediate, 2,3,4-trimethoxybenzoic acid has higher requirements for its purity and isomer content, especially there should be no impurities of 3,4,5-trimethoxybenzoic acid. The purity requirement is generally above 99.5%. [0003] It has been reported abroad that 2,3,4-trihydroxybenzoic acid is used as raw material, and 2,3,4-trimethoxybenzoic acid is obtained by methylation with dimethyl sulfate. The yield of this method is only 70%-80%. In addition, dimethyl sulfate is a highly toxic chemical and causes great pollution. Summary of the invention [0004] The purpose of the present invention is to provide a method for preparing 2,3,4-trimethoxybenzoic acid that can improve the yield and product purity, and meet its purity requirements as a pharmaceutical intermediate, and avoid the use of highly toxic sulf...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07C65/21C07C51/235
Inventor 张宗和徐浩黄嘉玲秦清
Owner 南京龙源天然多酚合成厂
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