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Method for preparing 4-methyl-5-ethoxazole

A technology of ethoxy oxazole and ethoxy is applied in the direction of educts, organic chemistry, products, etc. It can solve the problems of low product yield and purity, long time, low solubility, etc., and achieves mild process reaction conditions and reaction Improved yield and good process stability

Active Publication Date: 2019-04-16
迪嘉药业集团股份有限公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0006] After alkaline hydrolysis of ethyl 4-methyl-5-ethoxy-1,3-oxazole-2-carboxylate, distill off ethanol, the product solution obtained at this time basically does not contain organic solvent; then add acid to it to precipitate 5-ethoxy-4-methyl-oxazole-2-carboxylic acid, 5-ethoxy-4-methyl-oxazole-2-carboxylic acid has very low solubility in water, and the reaction proceeds in two phases, The reaction temperature is high (60°C). Once triggered, a large amount of gas will be generated instantly, which will easily cause material flushing and cause danger.
[0007] The 4-methyl-5-ethoxy oxazole generated by the decarboxylation reaction is directly in contact with a strong acidic aqueous solution, and is easily decomposed at 60°C, resulting in low product yield and purity; and the post-treatment requires steam distillation to remove the product from the system After the distillation is completed, the crude product is separated, and then the crude product is extracted with a solvent, dried, and distilled to obtain the product, which consumes a lot of energy and takes a long time

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0027] Add 300ml of toluene, 95.66g of 4-methyl-5-ethoxy-1,3-oxazole-2-carboxylic acid ethyl ester (0.48mol), 300ml of drinking water and 23.2g of sodium hydroxide ( 0.58mol), react at 20°C for 3h, separate the liquids, adjust the pH of the aqueous phase to 1.0 with hydrochloric acid, add 300ml of methyl tert-butyl ether, heat up to 30°C and react until no bubbles emerge. Adjust the pH value to 9 with sodium hydroxide, and separate the liquids. The organic phase was distilled under reduced pressure, and the fraction at 60-80°C was collected. 56.9 g of a colorless transparent oil was obtained, with a yield of 93.2%, a gas phase purity of 99.8%, and a liquid phase purity of 99.5%.

Embodiment 2

[0029] Add 1000ml toluene, 110.25g 4-methyl-5-ethoxy-1,3-oxazole-2-carboxylic acid ethyl ester (0.55mol), drinking water, 1000ml and 66.48g sodium hydroxide ( 1.66mol), react at 40°C for 2h, separate the liquids, adjust the pH of the aqueous phase to 2.5 with hydrochloric acid, add 1000ml of chloroform, heat up to 50°C, and react until no bubbles emerge. Adjust the pH value to 11 with sodium hydroxide, and separate the liquids. The organic phase was distilled under reduced pressure, and the fraction at 60-80°C was collected. 66.70 g of a colorless transparent oil was obtained, with a yield of 94.8%, a gas phase purity of 99.6%, and a liquid phase purity of 99.6%.

Embodiment 3

[0031] Put 700L toluene, 100.0Kg ethyl 4-methyl-5-ethoxy-1,3-oxazole-2-carboxylate (502mol), 700Kg drinking water and 40Kg sodium hydroxide (1000mol) into the 2000L reactor , react at 80°C for 1h, separate the liquids, adjust the pH of the aqueous phase to 2.0 with hydrochloric acid, add 700L of dichloromethane, heat up to 40°C and reflux until no bubbles emerge. Adjust the pH value to 13 with sodium hydroxide, and separate the liquids. The organic phase was distilled under reduced pressure, and the fraction at 60-80°C was collected. 60.19Kg of colorless transparent liquid was obtained, the yield was 94.3%, the gas phase purity was 99.7%, and the liquid phase purity was 99.8%.

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PUM

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Abstract

The invention relates to a method for preparing a key intermediate 4-methyl-5-ethoxazole of vitamin B6 and belongs to the technical field of crude drug preparation. The method for preparing 4-methyl-5-ethoxazole comprises the steps that firstly, 4-methyl-5-ethyoxyl-1,3-oxazole-2-nonanoic acid-ethyl ester, methylbenzene, drinking water and sodium hydroxide are sequentially put into a hydrolysis reaction still according to a certain proportion, and stirring, heat preservation and reacting are carried out; liquid separation is carried out, and the pH value of the water phase is adjusted to rangefrom 1.0 to 2.5; an organic solvent is added to the system obtained in the second step, reacting is carried out by controlling the temperature ranging from 30 DEG C to 50 DEG C until no carbon dioxideis generated; after decarboxylation is finished, the pH value is adjusted to be larger than or equal to 9.0, liquid separation is carried out, the organic phase is subjected to vacuum distillation, and 4-methyl-5-ethoxazole is obtained. The process is easy and safe to operate, and industrial production is easy.

Description

technical field [0001] The invention relates to a preparation method of 4-methyl-5-ethoxyxazole, a key intermediate of vitamin B6, and belongs to the technical field of preparation of raw materials. Background technique [0002] 4-Methyl-5-ethoxyoxazole is one of the main intermediates for the synthesis of vitamin B6. Its production process mainly adopts: 4-methyl-5-ethoxy-1,3-oxazole-2-carboxylic acid ethyl ester for alkali hydrolysis-acid analysis-decarboxylation-neutralization-distillation. In the prior art, after alkali hydrolysis of ethyl 4-methyl-5-ethoxy-1,3-oxazole-2-carboxylate, the liquid is separated and the water layer is retained. The water layer was distilled off under reduced pressure to remove ethanol, followed by acid analysis and decarboxylation by heating. [0003] Chinese patent CN102321043A discloses that after alkaline hydrolysis of ethyl 5-ethoxy-4-methyl-1,3-oxazole-2-carboxylate, the toluene layer is separated, the water layer is retained, and the ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07D263/42
CPCC07D263/42Y02P20/141
Inventor 丛日刚鞠传平肖川刘庆春梁鑫李双民田杰
Owner 迪嘉药业集团股份有限公司
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