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
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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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