Method for preparing 2-alkoxy-4-amino-5-chlorobenzoic acid

A technology of chlorobenzoic acid and alkoxy, which is applied in the field of preparation of 2-alkoxy-4-amino-5-chlorobenzoic acid, which can solve the difficulties in the treatment of nitrogen-containing wastewater, the inability to recycle DMF, and the existence of safety hazards, etc. problems, to avoid serious problems in production equipment, avoid safety and environmental hazards, and reduce raw material costs

Active Publication Date: 2009-10-28
CHONGQING ENSKY CHEM
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  • Abstract
  • Description
  • Claims
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AI Technical Summary

Problems solved by technology

[0010] There are following problems in this route: (1) DMF cannot be recovered, and the treatment of nitrogenous wastewater is a difficult problem; (2) there are polychlorinated by-products, which will always be brought into mosapride citrate Or metoclopramide, the purification of the finished product is a difficult problem; (3) the reaction from 4 → 5 is violently exothermic, and there is a potential safety hazard; (4) the cost is high

Method used

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  • Method for preparing 2-alkoxy-4-amino-5-chlorobenzoic acid

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Experimental program
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Effect test

Embodiment 1

[0020] Embodiment 1: Preparation of 4-amino-5-chloro-2-hydroxyl-benzoic acid (C)

[0021]

[0022] Method (1), add 43 grams of compound B, 41.5 grams of anhydrous potassium carbonate, and 300 milliliters of xylene into a 1 L reaction flask, and heat to reflux for 3 hours. Transfer the reaction solution into a 1L autoclave, replace the air in the autoclave twice with nitrogen, and slowly introduce carbon dioxide gas to the autoclave pressure of 7 kg / cm 2 , heating up to 120°C. In the kettle temperature 120-140 ℃, kettle pressure 10-15 kg / cm 2 React for 6-9 hours. The reaction kettle was cooled to room temperature, 500 ml of water was added, the water layer was separated, and the toluene layer was extracted twice with water. Combine the aqueous layers, adjust the pH to less than 2 with concentrated hydrochloric acid, and cool to precipitate crystals. Crude product was obtained by filtration. Recrystallized with acetone to obtain 46.9 g of compound C: melting point 188-18...

Embodiment 2

[0025] Embodiment 2: Preparation of 4-acetylamino-5-chloro-2-hydroxyl-benzoic acid (D)

[0026] Method A:

[0027]

[0028] Add 19 g of compound C, 30 ml of glacial acetic acid, and 20 ml of acetic anhydride into a 100 ml three-necked flask, stir at room temperature for 3 hours, evaporate about 30 ml of solvent under reduced pressure, cool the residue to room temperature, and drop 200 ml of water, precipitated, cooled, filtered, and washed with water to obtain a crude product. The crude product was recrystallized from ethanol / water to obtain 1.2 g of compound D2. The melting point is 240-242.5°C. The yield is 90.8%.

[0029] Method B:

[0030]

[0031] With reference to the method of above-mentioned method A, product B' is prepared from B with a yield of 92.2%.

[0032] With reference to the method (1) of embodiment 1, the yield 72.4% of product D is prepared by B '.

[0033] With reference to the method (2) of Example 1, the yield of Compound D prepared from Compou...

Embodiment 3

[0035] Embodiment 3: Preparation of 4-acetylamino-5-chloro-2 ethoxy-ethyl benzoate (G')

[0036]

[0037] Put 23 grams of compound D, 200 milliliters of acetone, 30 grams of anhydrous potassium carbonate, and 50 milliliters of diethyl sulfate into the reaction flask, heat and reflux for 5 hours, distill the solvent, cool the residue, add 200 milliliters of water, and adjust the pH to 8 with dilute hydrochloric acid , filtered, and the cake was washed with 95% ethanol and dried to obtain 26.3 g of light yellow solid, yield 92.0%, Mp147-149°C.

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Abstract

The invention discloses a method for preparing 2-alkoxy4-amino5-chlorobenzoic acid, which includes steps of sequentially carrying out acylation reaction, Kolbe-Schmitt reaction, esterification reaction and etherification reaction for compound 3-amino-4-chlorophenol to obtain a compound represented by formula G, and carrying out alkaline hydrolysis to the G. By employing the cheap 3-amino-4-chlorophenol as raw material, the invention avoids using of expensive NCS, greatly reduces raw material cost, and avoids safety and environmental protection hidden trouble caused by NCS employed by prior art; by introducing solvent to Kolbe-Schmitt reaction, yield of the reaction is greatly increased, cost is lowered, needed pressure is greatly reduced, and equipment investment of industrial production and safety hidden trouble due to high pressure reaction are reduced; in addition, the esterification reaction and the etherification reaction are carried out for one step, thereby avoiding production equipment corrosion problem caused by employing common esterification method, namely strong acid condition under catalysis of concentrated sulfuric acid or hydrogen chloride gas, and further reducing cost.

Description

technical field [0001] The invention relates to a preparation method of 2-alkoxy-4-amino-5-chlorobenzoic acid. Background technique [0002] Mosapride citrate is a selective serotonin 4 (5-HT4) receptor agonist, which promotes the production of acetylcholine by exciting the 5-HT4 receptors of cholinergic interneurons and myenteric plexuses in the gastrointestinal tract. release, thereby enhancing the motility of the gastrointestinal tract, improving the gastrointestinal symptoms of patients with functional dyspepsia, without affecting the secretion of gastric acid. It is mainly used for functional dyspepsia with heartburn, belching, nausea, vomiting, early satiety, upper abdominal distension, upper abdominal pain and other gastrointestinal symptoms. Because of its good curative effect and few side effects, it is widely used in clinic. At present, the sales of mosapride citrate in Japan, China, South Korea and India in Asia are as high as hundreds of millions of dollars. ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07C229/64C07C227/18C07C227/02
Inventor 黄玉明曹原张毅吴明亮杨成陈奉强
Owner CHONGQING ENSKY CHEM
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