Reaktion #54938

Reaktionsgleichung

4-oxo-4H-1-benzopyran-3- carboxaldehyde

cyanoacetic acid

→

trans-3-(4-oxo-4H-1-benzopyran-3-yl)-acrylonitrile

Lösungsmittel

pyridine

Reaktionsbedingungen

Aufarbeitung

1. 1
   Temperaturafter which time the whole mixture is further heated for 8 minutes
2. 2
   TemperaturAfter cooling
3. 3
   Filtrationthe separated crystals are recovered by filtration
4. 4
   workup.ADDITIONtreated with activated carbon
5. 5
   Sonstigerecrystallized three times from ethanol

Vorschrift

A mixture of 10.44 parts of 4-oxo-4H-1-benzopyran-3- carboxaldehyde and 5.4 parts of cyanoacetic acid are heated in an oil bath at 110° C., and to the mixture 25 volume parts of pyridine are added dropwise over about 30 seconds, after which time the whole mixture is further heated for 8 minutes. After cooling, the separated crystals are recovered by filtration, treated with activated carbon and recrystallized three times from ethanol. This procedure yields trans-3-(4-oxo-4H-1-benzopyran-3-yl)-acrylonitrile as pale-yellowish prisms. Melting point: 192°-194° C.

Quelle