PURPOSE: To obtain the title substance useful as an intermediate raw material for drugs from a readily obtainable inexpensive raw material in high yield by oxidizing a 1,1-diarylethylene glycol with molecular oxygen in the presence of a transition metal catalyst and base.

CONSTITUTION: A compound shown by formula I (Ar1 and Ar2 are halogen, NO2, NH2 or aryl which may be replaced with lower alkyl or lower alkoxy) is oxidized with molecular oxygen in the presence of a transition metal catalyst and a base (e.g. NaOH or KOH) at 0-200°C (preferably 50-100°C) to give a compound shown by formula II. One or a mixture selected from Pt, Pd, Rh, Ru, Ni, Fe, Co, Cu, etc., or an oxide, sulfide, chloride, etc.,thereof is used as the catalyst (e.g. Pt-C) and the amount thereof is preferably 0.1-10 wt.% based on the compound shown by formula I.