Method for preparing 1-proparagyl hydantoin
A technology of propargyl and propargyl glycine alkyl ester is applied in the field of preparation of 1-propargyl hydantoin, and achieves the effects of low production cost, reasonable process route and high purity
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Embodiment 1
[0030] (1) In the reactor with condensing reflux, stirring and dropping and heating device, add 142.3g ethyl glycine hydrochloride, 1000ml carbon tetrachloride, 212g triethylamine, stir, and heat up to 50~55°C, Slowly add 106g of 3-bromopropyne dropwise, react for 20 hours, filter the reactant, remove the solvent, distill under reduced pressure, collect fractions at 58-61°C / 300Pa to obtain 133 grams of light yellow oily liquid, yield 85%.
[0031] (2) 78g of the light yellow oily liquid obtained in the previous step is slowly added dropwise to 63g of 36% hydrochloric acid solution, and the reaction temperature is maintained at 25-30°C. After the dropwise addition, 47g of potassium cyanate aqueous solution is continued to be added dropwise, and the temperature is raised to 95-95°C after the dropwise addition. 100°C, keep warm for 5-6 hours, then cool down to 50°C, and enter the next step.
[0032] (3) Add 46 g of 20% hydrochloric acid dropwise to the mixed solution obtained in ...
Embodiment 2
[0034] (1) The operation process is the same as that of Example 1 step (1), changing glycine ethyl ester hydrochloride into glycine methyl ester hydrochloride, reacting for 30 hours, filtering the reactant, precipitating, and distilling under reduced pressure, collecting 54~57 °C / 300Pa fraction, 118 g of light yellow oily liquid was obtained, yield 83.5%.
[0035] (2) 71g of the light yellow oily liquid obtained in the previous step is slowly added dropwise to 60g of 36% hydrochloric acid solution, and the reaction temperature is maintained at 25-30°C. After the dropwise addition, 45g of potassium cyanate aqueous solution is continued to be added dropwise, and the temperature is raised to 95-95°C after the dropwise addition. 100°C, keep warm for 5-6 hours, then cool down to 50°C, and enter the next step.
[0036] (3) Add 46 g of 20% hydrochloric acid dropwise to the mixed solution obtained in the previous step to acidify it. After the drop is completed, the temperature is rais...
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