PURPOSE: To produce the titled compound useful as a precursor of anthraquinone, in high yield, by cyclizing benzal acetophenone in the presence of an acid catalyst, and carrying out the liquid-phase oxidation of the resultant 3-phenyl- 1-indanone with oxygen in the presence of a specific catalyst.

CONSTITUTION: Benzal acetophenone of formula I is cyclized in the presence of polyphosphoric acid and/or phosphorus pentoxide catalyst in an organic solvent essentially incompatible with said catalyst (e.g. toluene) to obtain 3-phenyl-1-indanone of formula II, which is oxidized with molecular oxygen in liquid phase in the presence of a cobalt salt and/or manganese salt catalyst (e.g. cobalt acetate) in an aliphatic carboxylic acid solvent (e.g. acetic acid) to obtain the objective compound of formula III. The starting compound of formula I can be synthesized easily in high yield by the reaction of benzaldehyde with acetophenone in the presence of an alkali catalyst.