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Indole-3-formic acid purification process

A technology for indole and formic acid, which is applied in the field of purification technology of indole-3-carboxylic acid, can solve the problems of color deterioration, high residue and high impurity content, and achieves the effects of being beneficial to industrialized production, easy to obtain raw materials, and easy to operate.

Inactive Publication Date: 2006-07-26
北京成宇化工有限公司 +1
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Problems solved by technology

[0003] The method for the production of indole-3-formic acid as industrialization in the early stage is to adopt the method for potassium permanganate oxindole-3-formaldehyde (Arm, Khim.Zh., 29,1062,1976), due to the strong strength of potassium permanganate Oxidation and the generation of manganese dioxide as a by-product make the color of the indole-3-carboxylic acid obtained is brown, and the impurity content is high, which is difficult to meet the requirements as a pharmaceutical raw material
[0004] In the recently published Japanese patent (JP flat 1-96168), a synthetic method for preparing indole-3-formaldehyde with silver oxide and oxygen as an oxidizing agent system and indole-3-formaldehyde is described. In the method, indole-3-formaldehyde The conversion rate of 3-formaldehyde is low, so that the residue of indole-3-formaldehyde in the product indole-3-carboxylic acid is high (greater than 5%)
[0005] In addition, described in Japanese patent (JP2000-53644) with silver oxide as catalyst, hydrogen peroxide is the preparation technology of indole-3-formic acid under oxidant, although the conversion rate of indole-3-formaldehyde is improved in this method , but the content of indole-3-carbaldehyde in the product indole-3-carboxylic acid is still around 2%
[0006] The color of indole-3-carboxylic acid with high impurity content will further deteriorate when placed at room temperature, and it is difficult to obtain qualified products. The indole-3-carboxylic acid produced by the existing method is difficult to guarantee the requirements as a pharmaceutical raw material

Method used

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[0037] Preparation of indole-3-carboxylic acid potassium salt solution

[0038] Add water (200 milliliters), potassium hydroxide (20.0 grams, 0.5 moles), indole-3-formaldehyde (14.5 grams, 0.1 moles) in the 500 milliliters three-neck reaction flasks with mechanical stirrer and reflux condenser, oxidation Silver (4.8 grams, 0.025 mole), be heated to 60 ℃, drip concentration and be 30% hydrogen peroxide aqueous solution (22.5 grams, 0.2 mole) reaction 5 hours, cool, filter (remove silver oxide and unreacted indole- 3-formaldehyde), to obtain 255 grams of aqueous solution of the potassium salt of indole-3-formic acid.

[0039] According to liquid chromatography analysis, the content of indole-3-carboxylic acid was 94.32%, and that of indole-3-carbaldehyde was 5.43%.

[0040] The test conditions of liquid chromatography are as follows:

[0041] Chromatograph: LC-10AT

[0042] Chromatographic column: 250×4.6mm SS EXSIL ODS 5μm

[0043] Mobile phase: methanol / water=6:4

[0044]...

Embodiment 1

[0049] The potassium salt solution of indole-3-carboxylic acid (100 grams, concentration of indole-3-carboxylic acid is 5.4%) prepared according to Reference Example 1 was warmed up to 55-60°C, and methyl butyl ketone (2 grams) was added , keep warm for 1 hour, cool down to room temperature, filter, add concentrated hydrochloric acid to the filtrate, adjust pH = 4-5, filter the precipitate, and dry to obtain 5.1 g of light yellow indole-3-carboxylic acid.

[0050] Liquid chromatography analysis: indole-3-carboxylic acid content: 99.54%; indole-3-carbaldehyde content: 0.07%.

Embodiment 2

[0052] The potassium salt solution of indole-3-carboxylic acid (100 grams, the concentration of indole-3-carboxylic acid is 5.4%) prepared according to Reference Example 1 was warmed up to 55-60° C., and methyl isopropyl ketone (2 grams ), heat preservation for 1 hour, cool to room temperature, filter, add concentrated hydrochloric acid to the filtrate, adjust pH=4~5, filter the precipitate, dry to obtain 4.9 grams of light yellow indole-3-carboxylic acid.

[0053] Liquid chromatography analysis: indole-3-carboxylic acid content: 99.71%; indole-3-carbaldehyde content: 0.08%.

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Abstract

The invention discloses a purifying process of indole-3-aminic acid, this process can accomplish by procedures as follows: 1)adding methyl ketones organic solvent into alkali metal salt solution of indole-3-aminic acid which is made by indole-3-formaldehyde; 2)adding reduction inorganic salt into alkali metal salt solution of indole-3-aminic acid which is made by indole-3-formaldehyde to reduce it; 3)acidizing the products of 1)and 2)by inorganic acid; 4)conductting recrystallization of the products uupwords to have high-purity indole-3-aminic acid. This invention is simple to operate, easy to find the material and low in cost. It is propitious to industrial production and adapt to the request of chemical industry, drug industry. ect.

Description

technical field [0001] The invention belongs to the field of refining process of fine chemical products, in particular to a process for purifying indole-3-carboxylic acid. Background technique [0002] Indole-3-carboxylic acid is an important fine chemical for the synthesis of medicines and pesticides. In the process of using as a pharmaceutical raw material, the content and type of impurities are strictly required (the content of indole-3-carboxylic acid is greater than 99.5%, and the content of indole-3-formaldehyde is less than 0.1%), while the existing industrial production of indole-3- The formic acid method has serious deficiencies. [0003] The method for the production of indole-3-formic acid as industrialization in the early stage is to adopt the method for potassium permanganate oxindole-3-formaldehyde (Arm, Khim.Zh., 29,1062,1976), due to the strong strength of potassium permanganate Oxidation and the generation of manganese dioxide as a by-product make the colo...

Claims

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Application Information

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IPC IPC(8): C07D209/42
Inventor 徐德国王道林姜瑞宏王玉平宋宇
Owner 北京成宇化工有限公司
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