A method of producing a 2,4'-dihydroxydiphenylsulfone.

摘要

A method of producing a high purity 2,4'-dihydroxydiphenylsulfone comprises producing a crude 2,4'-dihydroxydiphenylsulfone by mixing and heating one or more kinds of phenol and sulfuric acid to bring them into reaction with each other in the presence of at least one kind of catalyst selected from phosphonic acid, phosphinic acid and salts thereof in the absence of a solvent or in the presence of an aromatic hydrocarbon solvent having a boiling point at atmospheric pressure of 130 to 200 DEG C and purifying the crude 2,4'-dihydroxydiphenylsulfone thus produced using (1) a mixed solvent containing 5 to 20 weight % of at least one kind selected from lower aliphatic alcohols and 95 to 80 weight % of at least one kind selected from aromatic hydrocarbons not containing halogen, (2) a mixed solvent containing 10 to 40 weight % of at least one kind selected from ketones and 90 to 60 weight % of at least one kind selected from aromatic hydrocarbons not containing halogen or (3) a mixed solvent containing 10 to 40 weight % of at least one kind selected from esters of acetic acid and 90 to 60 weight % of at least one kind selected from aromatic hydrocarbons not containing halogen. According to the method, 2,4'-dihydroxydiphenylsulfone useful as developer for thermal recording paper can be produced efficiently with high selectivity and a high purity product can be obtained efficiently.