Process for producing 1-phenyl-1,3-propanediols having high optical purtiy

A process for producing an optically active 1-phenyl-1,3-propanediol having an optical purity as 100% ee comprising the steps of (1) dissolving a R or S-1-phenyl-1,3-propanediol having an optical purity of 21.4% ee to 95% ee and represented by the formula, ##STR5## wherein X is a halogen atom or an alkoxy group of 1 to 4 carbon atoms in a solvent selected from the group consisting of an aliphatic hydrocarbon, an alicyclic hydrocarbon, an ester, an ether, an aromatic compound, an alcohol, a glycol, water and mixtures thereof at an elevated temperature above room temperature and sufficient to dissolve said diol, (2) cooling the thus obtained solution at atmospheric pressure and in the absence of seeding, to crystallize one of R and S-1-phenyl-1,3-propanediol corresponding to an enantiomeric excess side, (3) subjecting the cooled solution to a suction filtration to collect the crystals and (4) drying the collected crystals under a reduced pressure.