PURPOSE: To obtain a methanol compound useful as a functional pigment in high yield at a low cost without causing fire and explosion hazard by reacting an alcohol with an aldehyde in the presence of a specific zirconium-based catalyst.

CONSTITUTION: The objective compound is produced by reacting (A) a secondary alcohol (e.g. 2-propanol) with (B) a fluorene-9-carbaldehyde [e.g. an aldehyde of formula (R1 to R9 are each H or a functional group)] in the presence of (C) a zirconium-based catalyst selected from zirconium alkoxide and hydrated zirconium oxide. The reaction is carried out e.g. at 0-150°C by using 3-200 pts.wt. of the component A based on 1 pt.wt. of the component B and 0.005-1mol of the component C based on 1mol of the component B.