PURPOSE: To prepare the titled compound, easily, in high yield and purity, by recrystallizing the ethylene oxide adduct of bisphenol S composed mainly of bis(hydroxyethoxyphenyl) sulfone in water and a water-soluble alcohol.

CONSTITUTION: The ethylene oxide adduct of bisphenol S composed mainly of bis(hydroxyethoxyphenyl) sulfone is recrystallized by heating in a mixture of water and a water-soluble alcohol (10:90W95:5 by weight) at 50W200°C, and cooling the solution. If necessary, the recrystallization is carried out in the presence of an alkali (e.g. sodium hydroxide, potassium hydroxide, etc.).

USE: Useful as a raw material for the preparation of heat-resistant material, and a corrosion-resistant, chemical-resistant and smoke-resistant polymers, an alkyd resin modifier, and a raw material of polyester resin and fiber, urethane resin, etc.