Preparation method of 2-amino-5-fluorobenzoic acid

The technology of fluorobenzoic acid and amino group is applied in the field of preparation of 2-amino-5-fluorobenzoic acid, and can solve the problems of difficulty in obtaining, decrease in alkalinity, decrease in reaction yield, etc., and achieves low cost and easy availability of raw materials and reaction conditions. Gentle, simple and safe effect

Inactive Publication Date: 2005-09-21
EAST CHINA UNIV OF SCI & TECH
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  • Claims
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Problems solved by technology

[0012] This method undergoes a process of first reduction and then oxidation. Within a certain temperature range, the speed of the reduction reaction usually increases with the increase of temperature, but too high a temperature may cause coking of organic matter, making the color of aniline darker. It also accelerates the carbon deposition process on the surface of the catalyst; while the oxidation of potassium permanganate is generally carried out under alkaline or neutral conditions, but due to the presence of amino groups on the aromatic ring and the generation of strong acids, the alkalinity of the reaction solution decreases. leading to a decrease in the reaction yield
Another factor is that the raw material 2-methyl-4-fluoronitrobenzene is not easy to obtain, the price is relatively high, and multiple recrystallizations are required in the whole process, resulting in a decrease in yield

Method used

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  • Preparation method of 2-amino-5-fluorobenzoic acid
  • Preparation method of 2-amino-5-fluorobenzoic acid
  • Preparation method of 2-amino-5-fluorobenzoic acid

Examples

Experimental program
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Effect test

Embodiment 1

[0024] First prepare the chloral hydrate solution, weigh 18.2 g of chloral hydrate, and dissolve it in 400 mL of water. Then prepare 4-fluoroaniline solution, weigh 11.1 g of 4-fluoroaniline and 22.3 g of hydroxylamine hydrochloride, pour them into 160 mL of water, add 9 mL of concentrated hydrochloric acid, and stir until a yellow and clear transparent solution is obtained.

[0025] Add the prepared chloral hydrate solution to the 1000mL three-necked flask equipped with mechanical stirring, spherical condenser and thermometer, and heat up the oil bath. Add 260 grams of anhydrous sodium sulfate during the heating process. The solution was milky white, and sodium sulfate could not be completely dissolved. After adding the prepared 4-fluoroaniline solution, white flocculent precipitates appeared immediately, and the temperature was raised to reflux. After reacting for 2 hours, the mixture was filtered under reduced pressure while hot to obtain a brown-yellow filter cake. The f...

Embodiment 2

[0027] Same as Example 1, after the feeding is completed, the temperature is raised to 95° C., reacted for 2 hours, and the aftertreatment is the same as above. A white solid (12.6 g of N-(4-fluorophenyl)-2-(hydroxyimine)acetamide) was obtained, yield: 69.3%.

Embodiment 3

[0029] Same as Example 1, after the feeding is completed, the temperature is raised to 95° C., reacted for 3 hours, and the aftertreatment is the same as above. 12.2 g of white solid (N-(4-fluorophenyl)-2-(hydroxyimine)acetamide) was obtained, yield: 67.0%.

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Abstract

The preparation method of 2-amino-5-fluobenzoic acid uses 4-fluoroaniline as raw material, and includes the following steps: making said raw material and hydrated chloral and oxammonium hydrochloride implement condensation reaction to obtain N-(4-fluorophenyl)-2-(hydroxyimide) acetamide, then making cyclization in concentrated sulfuric acid to produce 5-fluoro-1H-indole-2,3-diketone, and finally, under the alkaline condition using oxydol to make oxidation so as to obtain the invented 2-amino-5-fluorobenzoic acid.

Description

technical field [0001] The present invention relates to an improved process for the preparation of 2-amino-5-fluorobenzoic acid. Background technique [0002] 2-Amino-5-fluorobenzoic acid is a very important precursor for the synthesis of drugs, herbicides, plant growth regulators and quinoline fungicides. Specifically, it can be used as the precursor of the virus-killing agent of HIV infectious disease; as the precursor of the anti-viral agent of herpes virus; the preparation of phyllophylline and its analogues are used as hypoglycemic agents for the treatment of diabetes; the preparation of aminoquinone Phylin as an anticancer agent; preparation of triazine and its analogs for local ischemia, hypoglycemia, cerebral vasospasm, Alzheimer's disease, Parkinson's disease, Huntington's chorea, atrophy neuroprotective agents in schizophrenia, myelopathy, and schizophrenia. [0003] Many methods for the preparation of 2-amino-5-fluorobenzoic acid have been reported in the existi...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C07C227/02C07C229/56
Inventor 陈卫东钱旭红宋恭华尹江平
Owner EAST CHINA UNIV OF SCI & TECH
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