Reaction #48035

Reaction equation

ethyl 1-(4-chlorophenyl)-5-phenyl-4,5-dihydro-(1H)-pyrazole-3-carboxylate

water

NaOH

→

1-(4-chlorophenyl)-5-phenyl-4,5-dihydro-(1H)-pyrazole-3-carboxylic acid

Yield 78.2%

Solvents

methanol

Conditions

Workup

1. 1
   Temperaturethe resulting solution is heated
2. 2
   Temperatureat reflux temperature for 2 hours
3. 3
   OtherThe methanol is partly removed by evaporation
4. 4
   workup.DISSOLUTIONthe residue is dissolved in a mixture of water and ethyl acetate
5. 5
   workup.ADDITIONIce, concentrated HCl (20 ml) and ethyl acetate are successively added
6. 6
   Otherthe ethyl acetate layer collected
7. 7
   Dryingdried over MgSO4
8. 8
   Filtrationfiltered
9. 9
   Concentrationconcentrated in vacuo
10. 10
    WashThe resulting residue is washed with diethyl ether (100 ml) and diisopropyl ether respectively

Procedure

Part C: To a stirred suspension of ethyl 1-(4-chlorophenyl)-5-phenyl-4,5-dihydro-(1H)-pyrazole-3-carboxylate (23.0 gram, 0.07 mol) in methanol (200 ml) is added water (15 ml) and concentrated NaOH (10 ml) and the resulting solution is heated at reflux temperature for 2 hours. The methanol is partly removed by evaporation and the residue is dissolved in a mixture of water and ethyl acetate. Ice, concentrated HCl (20 ml) and ethyl acetate are successively added, the ethyl acetate layer collected, dried over MgSO4, filtered and concentrated in vacuo. The resulting residue is washed with diethyl ether (100 ml) and diisopropyl ether respectively, to give 1-(4-chlorophenyl)-5-phenyl-4,5-dihydro-(1H)-pyrazole-3-carboxylic acid (16.46 gram, 78% yield). Melting point: 177-179° C.

Source