Patent ID: 7189880

Claim:
A process for producing 2,4′-dihydroxydiphenylsulfone which comprises separating 4,4′-dihydroxydiphenylsulfone by crystallization from a mixture comprising 4,4′-dihydroxydiphenylsulfone, 2,4′-dihydroxydiphenylsulfone, phenolsulfonic acid and phenol which is obtained by dehydration of phenol and sulfuric acid or phenolsulfonic acid so that a mixture having a content of 2,4′-dihydroxydiphenylsulfone greater than a content of 4,4′-dihydroxydiphenylsulfone is obtained, crystallizing 2,4′-dihydroxydiphenylsulfone by adjusting a composition of a solvent of an obtained mixture so that a ratio of an amount by weight of phenol to an amount by weight of water is in a range of 10:90 to 90:10, and separating 2,4′-dihydroxydiphenylsulfone by filtration.