Process for preparing aryl acetic acid derivatives

A process for preparing an aryl acetic acid derivative represented by the formula

• Ar(CH.sub.2 COY).sub.n
• wherein Ar is phenyl, polynuclear aromatic group or heterocyclic group optionally substituted with halogen, hydroxyl, alkyl, alkenyl, aralkyl, alkoxy, acyloxy, aralkyloxy or phenoxy having or having not substituents, the substituent of said Ar is 1 to 3 in number and may be different or the same, n is an integer of 1 to 3, and Y is hydroxyl, or alkoxy, the process comprising hydrolyzing a dichloroethenyl compound represented by the formula
• Ar(CH.dbd.CCl.sub.2).sub.n
• when Ar and n are defined as above in the presence of about 0.01 to about 10 mole alkaline substance per mole of the dichloroethenyl compound in water and an organic solvent selected from the group consisting of methanol, ethanol and like alcohols, dimethylformamide, dimethylsulfoxide, dioxane, tetrahydrofuran and like ethers, benzene, toluene and like aromatic hydrocarbons or a mixture thereof, said alkaline substance being selected from the group consisting of alkali metal hydroxides, alkaline earth metal hydroxides and alkali metal alkoxides.