C([O:3][C:4](=[O:22])[CH2:5][CH:6]([C:8]1[CH:13]=[CH:12][C:11]([C:14]2[CH:19]=[CH:18][C:17]([F:20])=[CH:16][C:15]=2[F:21])=[CH:10][CH:9]=1)[CH3:7])C.[OH-].[K+]>C(O)C>[F:21][C:15]1[CH:16]=[C:17]([F:20])[CH:18]=[CH:19][C:14]=1[C:11]1[CH:12]=[CH:13][C:8]([CH:6]([CH3:7])[CH2:5][C:4]([OH:22])=[O:3])=[CH:9][CH:10]=13.04 g. of 3-(2',4'-difluoro-4-biphenylyl)butyric acid ethyl ester and 1 g. of KOH in 25 ml. of ethanol are heated under reflux for 2 hours. The mixture is evaporated. The residue is dissolved in water and the solution is washed with ether and acidified to pH 3 with hydrochloric acid and worked up in the customary manner to give 3-(2',4'-difluoro-4-biphenylyl)-butyric acid, m.p. 109°-110°.
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