23.2 g. of 4-acetyl-2',4'-difluorobiphenyl, obtainable by reacting 2,4-difluorobiphenyl with acetyl chloride in the presence of AlCl3, and 11.1 ml. of ethyl bromoacetate are dissolved in a mixture of 75 ml. of benzene and 75 ml. of toluene. A 40 ml. portion of the resulting solution is added to 7 g. of zinc powder, previously washed successively with 1% hydrochloric acid, water and acetone and dried and the mixture is warmed to 70° with stirring and under a nitrogen atmosphere. After the reaction has begun, the remainder of the solution is added dropwise, the mixture is heated under reflux for one hour and cooled and 40 ml. of 20% sulfuric acid are added drop-wise in order to decompose the alcoholate Z--C(CH3) (OZnBr)--CH2 --COOC2H5 (Z is 2',4'-difluoro-4-biphenylyl). The organic phase is separated off and worked up in the customary manner to give 3-(2',4'-difluoro-4-biphenylyl)-3-hydroxybutyric acid ethyl ester, m.p. 96°-97° C.
