反应详情

0.35 mol diphosgene is added dropwise over 1 hour to a mixture of 0.28 mol of the methyl ester of asparagine and 0.4 g activated charcoal in 400 mL dioxane under N2. The reaction mixture is then heated and stirred at reflux for 21/2 hours. The reaction mixture is then cooled, filtered, and concentrated to dryness by rotary evaporator, keeping exposure to moisture to a minimum. The crude product is re-dissolved in 100 mL THF, and the pH of the solution is adjusted to 5.5-6.0 by addition of pyridine. The product mixture is again filtered, and the filtrate is fractionally distilled to give asparagine methyl ester isocyanate.

1. temperatureThe reaction mixture is then heated
2. temperatureat reflux for 21/2 hours
3. temperatureThe reaction mixture is then cooled
4. filtrationfiltered
5. concentrationconcentrated to dryness by rotary evaporator
6. dissolutionThe crude product is re-dissolved in 100 mL THF
7. additionthe pH of the solution is adjusted to 5.5-6.0 by addition of pyridine
8. filtrationThe product mixture is again filtered
9. distillationthe filtrate is fractionally distilled