Water → 1-(4-Carboxy-3-chlorophenyl)-1H-pyrazole-3-carboxylic acid
Reaction equation
[Cl:1][C:2]1[CH:10]=[C:9]([N:11]2[CH:15]=[CH:14][C:13]([CH3:16])=[N:12]2)[CH:8]=[CH:7][C:3]=1[C:4]([OH:6])=[O:5].[OH-:17].[K+].[Mn]([O-])(=O)(=O)=O.[K+].[OH2:25]>>[C:4]([C:3]1[CH:7]=[CH:8][C:9]([N:11]2[CH:15]=[CH:14][C:13]([C:16]([OH:25])=[O:17])=[N:12]2)=[CH:10][C:2]=1[Cl:1])([OH:6])=[O:5]Participants
5
Procedure
A vigorously stirred solution of 2-chloro-4-(3-methyl-1 H-pyrazol-1-yl)benzoic acid (7.08 g, 30.0 mmol) and 1 N potassium hydroxide (30 mL, 30.0 mmol) in water (200 mL) was heated to between 60–65° C. and treated gradually over ninety minutes with several aliquots of solid potassium permanganate (Total: 49.78 g, 315 mmol, 5.25 equivalents). The mixture was heated for an additional 2.5 hours (4 hours total). After cooling to room temperature, the mixture was filtered and evaporated to a residue. The residue was dissolved in 2 N hydrochloric acid and extracted with ethyl acetate (3×). The combined organic phase was washed with water, dried over anhydrous sodium sulfate, filtered, and the solvent removed in vacuo to yield, after crystallization from a mixture of ethyl acetate-diethyl ether-hexane, the title compound (1.27 g, 4.8 mmol, 16%) as a homogeneous solid, m.p. 260–263° C.;