反应详情

27.47 g (0.125 mol) of 1-ethoxycarbonyl-4-methoxycarbonylmethyl-semicarbazide were dissolved in 95 ml (0.38 mol) of 4-M potassium hydroxide solution and heated on a steam-bath for 1.5 hours. The resulting solution was cooled to room temperature, acidified to pH 1 with concentrated hydrochloric acid and evaporated in vacuo to give a colourless solid. This solid was extracted with three 90 ml portions of boiling methanol. The extracts were filtered, combined and added to 400 ml of methanolic hydrogen chloride. The mixture was left to stand at room temperature overnight and then evaporated in vacuo to give a colourless solid. This solid was recrystallized from methanol to give 7.50 g (35%) of methyl 3,5-dioxo-1,2,4-triazolidine-4-acetate of melting point 215°-218° C.

1. temperatureheated on a steam-bath for 1.5 hours
2. customevaporated in vacuo
3. customto give a colourless solid
4. extractionThis solid was extracted with three 90 ml portions of boiling methanol
5. filtrationThe extracts were filtered
6. additionadded to 400 ml of methanolic hydrogen chloride
7. waitThe mixture was left
8. customevaporated in vacuo
9. customto give a colourless solid
10. customThis solid was recrystallized from methanol