Reaktion #334390

Reaktionsgleichung

charcoal

diphosgene

isoleucine

→

isoleucine methyl ester isocyanate

Lösungsmittel

dioxane

Reaktionsbedingungen

Aufarbeitung

1. 1
   TemperaturThe reaction mixture is then heated
2. 2
   Temperaturat reflux for 21/2 hours
3. 3
   TemperaturThe reaction mixture is then cooled
4. 4
   Filtrationfiltered
5. 5
   Einengenconcentrated to dryness by rotary evaporator
6. 6
   workup.DISSOLUTIONThe crude product is re-dissolved in 100 mL THF
7. 7
   workup.ADDITIONthe pH of the solution is adjusted to 5.5-6.0 by addition of pyridine
8. 8
   FiltrationThe product mixture is again filtered
9. 9
   workup.DISTILLATIONthe filtrate is fractionally distilled

Vorschrift

0.35 mol diphosgene is added dropwise over 1 hour to a mixture of 0.28 mol of the methyl ester of isoleucine 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 isoleucine methyl ester isocyanate.

Quelle