Réaction #831228

Équation de réaction

CaCl2

thionyl chloride

p-nitrophenol

trans-urocanic acid

→

p-Nitrophenyl trans-3-(1H-imidazol-4-yl)-2-propenoate

Conditions de réaction

Traitement

1. 1
   Autreequipped with a drying tube
2. 2
   Autreis progressively brought to 140° C
3. 3
   ExtractionA brown powder is extracted with CHCl3 /MeOH (150 ml, 2:1)
4. 4
   Températurewhile heating
5. 5
   AutreThe undissolved material is separated by filtration
6. 6
   workup.ADDITIONthe filtrate is treated with active charcoal
7. 7
   ConcentrationConcentration
8. 8
   workup.ADDITIONis added so as
9. 9
   Autreprecipitation of a solid (1.96 g; overall crude yield: 61%)
10. 10
    AutreThe latter is recrystallized from MeOH
11. 11
    Lavagethe product is washed with diethyl ether in order
12. 12
    Autreto remove any trace of p-nitrophenol
13. 13
    Autregiving a crystalline white solid, M.p. 220°-222° C.

Mode opératoire

2 ml (27.5 mmol) of freshly distilled thionyl chloride are added to a finely ground mixture of 1.51 g (10.8 mmol) of p-nitrophenol and 1.5 g (10.8 mmol) of trans-urocanic acid in a round-bottomed flask equipped with a drying tube containing CaCl2. The mixture is progressively brought to 140° C. After 4 h, the mixture is slowly cooled to room temperature. A brown powder is extracted with CHCl3 /MeOH (150 ml, 2:1) while heating. The undissolved material is separated by filtration and the filtrate is treated with active charcoal. Concentration is carried out under vacuum and diethyl ether is added so as to induce precipitation of a solid (1.96 g; overall crude yield: 61%). The latter is recrystallized from MeOH and the product is washed with diethyl ether in order to remove any trace of p-nitrophenol, giving a crystalline white solid, M.p. 220°-222° C.

Source