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| Number | Title | Issue Date |
| 6974886 | Process for producing dihydroxydiphenylsulfone The present invention provides a process for producing dihydroxydiphenylsulfone wherein trihydroxytriphenylsulfone and coloring impurities are effectively removed without altering the isomeric composition of dihydroxydiphenylsulfone. In particular, the present inven... | 12/13/2005 |
| 6965054 | Process for producing mixture of dihydroxydiphenylsulfone isomers The present invention provides a process for producing a mixture of dihydroxydiphenylsulfone isomers containing 2,4′-dihydroxydiphenylsulfone, the process comprising heating 4,4′-dihydroxydiphenylsulfone or a mixture of dihydroxydiphenylsulfone isomers containin... | 11/15/2005 |
| 6861562 | Process for producing mixture of dihydroxydiphenylsulfone isomers The present invention provides a process for producing a mixture of 4,4′- and 2,4′-dihydroxydiphenylsulfones comprising heating trihydroxytriphenyldisulfone or a mixture of dihydroxydiphenylsulfone isomers containing trihydroxytriphenyldisulfone in the presence ... | 03/01/2005 |
| 5596128 | Sulfonating agent and sulfonation process A sulfonating agent represented by the general formula ##STR1## wherein the groups R1 are the same or different and are each a lower alkyl group having 1 to 3 carbon atoms, n is an integer of 3, 4 or 5, m is an integer of 1 or 2, and n+mà£... | 01/21/1997 |
| 5241121 | Process for preparation of 4,4'-dihydroxydiphenylsulfone A process for preparing 4,4'-dihydroxydiphenylsulfone, the process including heating 4,4'-dihydroxydiphenylsulfone and 2,4'-dihydroxydiphenylsulfone in the presence of an acid catalyst to isomerize the 2,4'-dihydroxydiphenylsulfone into 4,4'-dihydrox... | 08/31/1993 |
| 5189223 | Process for preparation of 4,4'-dihydroxydiphenylsulfone The present invention provides a process for preparing 4,4'-dihydroxydiphenylsulfone which comprises subjecting a phenol and a sulfonating agent to dehydration reaction in the presence of mesitylene as a reaction medium while the produced 4,4'-dihydroxydi... | 02/23/1993 |
| 4820831 | Process for preparing 4,4'-dihydroxydiphenyl sulfone having high purity The process of the present invention is a process for preparing 4,4'-dihydroxydiphenyl sulfone by subjecting phenol, and a sulfonating agent or phenolsulfonic acid to a dehydration reaction in the presence of a solvent, subsequently maintaining the reacti... | 04/11/1989 |
| 4558161 | Process for preparing halo-substituted diarylsulfones A process for preparing diarylsulfone, the process comprising reacting chlorosulfonic acid with a mixture of (i) aromatic hydrocarbon represented by the formula ##STR1## wherein one of X and Y is a halogen atom and the other is a halogen atom or... | 12/10/1985 |
| 4162270 | Process for producing 4,4'-dihydroxydiphenylsulfone of high purity In a process for producing 4,4'-dihydroxydiphenylsulfone by reacting phenol with sulfuric acid in the presence of a solvent, an improvement which comprises using at least a member selected from the group consisting of chlorobenzene, dichlorobenzene, trich... | 07/24/1979 |
