[F:1][C:2]([F:19])([F:18])[C:3]1[CH:4]=[C:5]([C:9]2[CH:13]=[C:12]([C:14]([O:16]C)=[O:15])[S:11][N:10]=2)[CH:6]=[CH:7][CH:8]=1.[OH-].[K+].Cl.FC(F)(F)C1C=C(C2C=C(C([O-])=O)SN=2)C=CC=1>>[F:19][C:2]([F:1])([F:18])[C:3]1[CH:4]=[C:5]([C:9]2[CH:13]=[C:12]([C:14]([OH:16])=[O:15])[S:11][N:10]=2)[CH:6]=[CH:7][CH:8]=1A solution of 1.6 g. of methyl 3-(3-trifluoromethylphenyl)-5-isothiazolecarboxylate in 30 ml. of 95% alcohol containing 1.0 g. of potassium hydroxide was heated at reflux for one hour. The reaction mixture then was added to 50 g. of ice, and the aqueous solution was acidified by the addition of 12 N aqueous hydrochloric acid. The product which precipitated was collected by filtration and crystallized from toluene and hexane to provide 1.3 g. of 3-(3-trifluoromethylphenyl)-5-isothiazolecarboxylate acid. Yield 85%. M.P. 162.5°-164° C.
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