[NH2:1][C:2]1[N:6]([C:7]2[CH:8]=[C:9]([CH:13]=[CH:14][CH:15]=2)[C:10]([OH:12])=[O:11])[N:5]=[CH:4][C:3]=1[C:16]([O:18]CC)=[O:17].[OH-].[Na+].Cl>O>[NH2:1][C:2]1[N:6]([C:7]2[CH:8]=[C:9]([CH:13]=[CH:14][CH:15]=2)[C:10]([OH:12])=[O:11])[N:5]=[CH:4][C:3]=1[C:16]([OH:18])=[O:17]The mixture of 3-(5-amino-4-ethoxycarbonylpyrazol-1-yl)benzoic acid (5.9 g) and sodium hydroxide (2.1 g) in water (15 ml) was stirred for 2 hours at 80° C. To the reaction mixture was added water and the mixture was adjusted to pH 3.5 with 6N-hydrochloric acid. The isolated precipitate was collected by filtration washed with water and dried to give 3-(5-amino-4-carboxypyrazol-1-yl)benzoic acid (5.1 g).
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