Reaktion #94333

Reaktionsgleichung

2-thienylacetic acid methyl ester

acetic anhydride

H3PO4

→

5-acetyl-2-thienylacetic acid methyl ester

Reaktionsbedingungen

Aufarbeitung

1. 1
   Temperatur(0.04 mol) was heated at 70°-80° C.
2. 2
   Temperaturcooling
3. 3
   TemperaturThe mixture was maintained between 70°-80° C. for 3 hrs
4. 4
   workup.ADDITION, and then, poured onto ice-water
5. 5
   Extraktionfollowed by extraction with ether
6. 6
   WaschenOrganic layer was washed with water several times
7. 7
   Sonstigedried over anhyd
8. 8
   SonstigeMgSO4 and evaporated
9. 9
   workup.DISTILLATIONThe residue was distilled at 2 mmHg
10. 10
    Sonstigea fraction between 160° C. and 172° C. was collected
11. 11
    SonstigeThis material was gradually crystallized
12. 12
    Sonstigecould be recrystallized from the mixture of light-petroleum and benzene

Vorschrift

A mixture of 2-thienylacetic acid methyl ester, 1.41 g. (0.01 mol) and acetic anhydride, 4.2 g. (0.04 mol) was heated at 70°-80° C. and 0.2 g. of 85% H3PO4 was added dropwise with mechanical stirring. The reaction was somewhat exothermic but cooling was not necessary. The mixture was maintained between 70°-80° C. for 3 hrs., and then, poured onto ice-water followed by extraction with ether. Organic layer was washed with water several times, dried over anhyd. MgSO4 and evaporated. The residue was distilled at 2 mmHg and a fraction between 160° C. and 172° C. was collected. This material was gradually crystallized and could be recrystallized from the mixture of light-petroleum and benzene. m.p. 43°-44° C. Yield; 1.39 g. (76.5%)

Quelle