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Preparation method for 4-methyl-5-ethyoxyl-oxazole

A technology of ethoxy and methyl, which is applied in the field of preparation of 4-methyl-5-ethoxy-oxazole, can solve the problems of many impurities in products, many side reactions of cyclization reactions, and many impurities, and achieve easy The effect of industrial production, mild reaction conditions, and simple process operation

Inactive Publication Date: 2012-01-18
HUBEI HUISHENG PHARMA
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0003] The above-mentioned ring-closing dehydrating agent used has phosgene / fatty tertiary amine / chloroform, phosphorus pentoxide / chloroform, phosphorus oxychloride / triethylamine / toluene, etc., adopting the above-mentioned ring-closing dehydrating agent to react more or less exists: Combination reaction is not complete, many impurities, low yield and other disadvantages; using phosphorus pentoxide / chloroform cyclodehydrating agent, the material is easy to form hard lumps during the reaction process, and the operation is very difficult; using phosphorus pentoxide / chloroform as cyclodehydration Not only is the cyclization reaction incomplete, but phosgene is highly toxic, and transportation is also very inconvenient; the cyclization reaction is performed at 80°C with phosphorus oxychloride / triethylamine / toluene dehydrating agent, and there are many side reactions in the cyclization reaction , the product has many impurities, and the toluene used in the reaction process is poisonous, which not only affects human health, but also causes environmental pollution

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0018] In a four-necked flask equipped with a condenser, mechanical stirring, and a thermometer, 264 g (2.6 mol) of triethylamine, 200 g (content 96%, 0.88 mol) of ethyl N-ethoxyoxalylalanine, dimethyl Add 3.2 g (0.0438 mol) of methyl formamide, then slowly add 133 g (0.87 mol) of phosphorus oxychloride, react at 60°C for 1 hour, then raise the temperature to 80-85°C for 7 hours. Cool to 50°C, add 350 g of water for hydrolysis, separate the water layer, add alkali to the water layer and recover triethylamine; add 20% sodium hydroxide aqueous solution (about 250 ml) to the organic layer for hydrolysis, adjust the pH value to 12, and distill out ethanol under reduced pressure and water, cooled to below 30°C, and added sulfuric acid to adjust the pH value to 2.0. Heat up to 65℃~70℃ for decarboxylation until no CO 2 Gas is generated, and the pH value is adjusted to 8.0 with alkali, extracted with chloroform, the organic layer is dried with anhydrous sodium sulfate, and the ch...

Embodiment 2

[0020] In a four-necked flask equipped with a condenser, mechanical stirring, and a thermometer, 352 g (3.48 mol) of triethylamine, 200 g (content 96%, 0.88 mol) of ethyl N-ethoxyoxalylalanine, dimethyl Add 13 g (0.18 mol) of methyl formamide, then slowly add 143 g (0.93 mol) of phosphorus oxychloride, react at 60°C for 1 hour, then raise the temperature to 80-85°C for 7 hours. Cool to 50°C, add 380g of water for hydrolysis, separate the water layer, add alkali to the water layer and recover triethylamine; add 20% aqueous sodium hydroxide solution (about 260ml) to the organic layer for hydrolysis, adjust the pH value to 13, and distill out ethanol under reduced pressure and water, cooled to below 30°C, and added sulfuric acid to adjust the pH value to 2.5. Heat up to 65℃~70℃ for decarboxylation until no CO 2 Gas is generated, and the pH value is adjusted to 8.5 with alkali, extracted with chloroform, the organic layer is dried with anhydrous sodium sulfate, and the chlorof...

Embodiment 3

[0022] In a four-necked flask equipped with a condenser, mechanical stirring, and a thermometer, 264 g (2.6 mol) of triethylamine, 200 g (content 96%, 0.88 mol) of ethyl N-ethoxyoxalylalanine, dimethyl 13 g (0.18 mol) of methyl formamide, then slowly added 133 g (0.87 mol) of phosphorus oxychloride, reacted at 60°C for 1 hour, then raised the temperature to 80-85°C for 7 hours. Cool to 50°C, add 350g of water for hydrolysis, separate the water layer, add alkali to the water layer and recover triethylamine; add 20% sodium hydroxide aqueous solution (about 250ml) to the organic layer for hydrolysis, adjust the pH value to 14, and distill out ethanol under reduced pressure Mix with water, cool to below 30°C, add sulfuric acid to adjust the pH value to 3.0; heat up to 65°C-70°C for decarboxylation until there is no CO 2 Gas is generated, and the pH value is adjusted to 9.0 with alkali, extracted with chloroform, the organic layer is dried with anhydrous sodium sulfate, and the ...

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Abstract

The invention relates to a preparation method for 4-methyl-5-ethyoxyl-oxazole. The preparation method for the 4-methyl-5-ethyoxyl-oxazole comprises the following steps of: performing cyclization reaction on N-ethoxyl oxalyl alanine ethyl ester under the action of phosphorus oxychloride / triethylamine / dimethylformamide used as a cyclization dehydrating agent at the temperature of between 40 and 60 DEG C for 0.5 to 1 hour; heating to 75 to 100 DEG C and reacting for 5 to 10 hours; hydrolyzing the reaction materials and separating out a water layer; adding an aqueous solution of sodium hydroxide into an organic layer to hydrolyze, adjusting the pH value to be 12 to 14, distilling to obtain ethanol and adjusting the pH value to be 2.0 to 3.0 by adding sulfuric acid; heating to 65 DEG C to perform decarboxylation; adjusting the pH value to 8.0 to 10.0 by using alkali; after chloroform extraction, drying the organic layer by using anhydrous sodium sulfate; and distilling the chloroform under normal pressure to obtain the target product 4-methyl-5-ethyoxyl-oxazole. The process is easy to operate and by the preparation method, industrialized production is easy to realize; the reaction condition is mild, side reaction is few, reaction yield is high and the product content is high; and toxic methylbenzene is not used, so physical health of staff and environmental protection are facilitated.

Description

technical field [0001] The invention relates to a vitamin B 6 The preparation method of the key intermediate 4-methyl-5-ethoxy-oxazole. Background technique [0002] The current production method is to synthesize 4-methyl-5-ethoxy-2-oxazole by dehydrating ethyl N-ethoxyoxalylalanine in phosphorus oxychloride / triethylamine / toluene cyclization system ethyl ester, and the latter synthesized the target product through three steps of hydrolysis, acid precipitation and decarboxylation. [0003] The above-mentioned ring-closing dehydrating agent used has phosgene / fatty tertiary amine / chloroform, phosphorus pentoxide / chloroform, phosphorus oxychloride / triethylamine / toluene, etc., adopting the above-mentioned ring-closing dehydrating agent to react more or less exists: Combination reaction is not complete, many impurities, low yield and other disadvantages; using phosphorus pentoxide / chloroform cyclodehydrating agent, the material is easy to form hard lumps during the reaction pro...

Claims

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Application Information

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IPC IPC(8): C07D263/42
Inventor 陈先保
Owner HUBEI HUISHENG PHARMA
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