Reaktion #336249

Reaktionsgleichung

Dicyclohexyl-carbodiimide

N-carbobenzoxy-β-benzyl-L-aspartic acid

p-nitrophenol

→

N-Carbobenzoxy-β-Benzyl-L-Aspartic Acid p-Nitrophenyl Ester

Lösungsmittel

ethyl acetate

ethyl acetate

Reaktionsbedingungen

Aufarbeitung

1. 1
   Temperaturthe solution is cooled to below 5° C
2. 2
   workup.ADDITIONadded
3. 3
   Temperaturmaintaining the temperature below 5° C
4. 4
   workup.WAITfor three hours at 20°-30° C
5. 5
   SonstigeThe dicyclohexylurea byproduct is removed by filtration
6. 6
   Waschenwashed with ethyl acetate (20-30 L)
7. 7
   EinengenThe filtrate is concentrated in vacuo below 60° C
8. 8
   workup.DISSOLUTIONThe concentrate is dissolved in a mixture of hot isopropyl alcohol (25-40 L)
9. 9
   workup.DISTILLATIONdistilled water (2-5 L)
10. 10
    Temperaturcooled below 25° C
11. 11
    SonstigeThe solids are collected on a filter
12. 12
    Waschenrinsed with isopropyl alcohol
13. 13
    Sonstigedried below 40° C
14. 14
    Sonstigespecific rotation=-15° to 18° (C=1, DMF)

Vorschrift

N-carbobenzoxy-β-benzyl-L-aspartic acid (12 Kg) and p-nitrophenol (5.1 Kg) are dissolved in ethyl acetate (20-30 L) and the solution is cooled to below 5° C. Dicyclohexyl-carbodiimide (7.6 Kg) is dissolved in ethyl acetate (8-12 L) and added, maintaining the temperature below 5° C. The solution is stirred at reduced temperature for two hours and then for three hours at 20°-30° C. The dicyclohexylurea byproduct is removed by filtration and washed with ethyl acetate (20-30 L). The filtrate is concentrated in vacuo below 60° C. The concentrate is dissolved in a mixture of hot isopropyl alcohol (25-40 L) and distilled water (2-5 L) and cooled below 25° C. The solids are collected on a filter, rinsed with isopropyl alcohol and dried below 40° C. Melting point=76°-79° C.; specific rotation=-15° to 18° (C=1, DMF).

Quelle