PRODUCTION OF 2-SUBSTITUTED 1,3-PROPANEDIOL

PROBLEM TO BE SOLVED: To produce the subject compound useful as a synthetic intermediate of pharmaceutical and agrochemical agents selectively on an industrial scale at a low cost using an easily handleable solvent by reacting a specific aldehyde with a formalin aqueous solution in a specific solvent to monohydroxylate at the α-position of the aldehyde followed by reducing the reaction product. SOLUTION: (C) A compound of formula I [R is a (substituted) alkyl, a (substituted) aryl or a (substituted) aralkyl] is made to react with (D) an aqueous solution of formalin in the presence of (B) a basic catalyst such as an alkali metal carbonate or an alkali metal hydroxide in (A) an ether solvent of >50 deg.C in a boiling point (e.g. tetrahydrofuran, tetrahydropyran or dioxane) to monohydroxymethylate the α-position of a component C. Subsequently, the reaction product is reduced to obtain a compound of formula II.