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AssigneeSugai Chemical Industry Co., Ltd.
InventorsKoji Nishihara, Takeshi Hashimoto, Shunsaku Tanaka, Katsuhiko Sato
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A process for producing 4,4'-diphenyldisulfonic acid is disclosed, which comprises the steps of adding a sulfonating agent to molten diphenyl at a temperature within a range of 130.degree. to 145.degree. C., and when crystallization commences of 4,4'-diphenyldisulfonic acid within such temperature range, cooling the reaction mixture to a temperature within a range of 115.degree. to 127.degree. C., and letting the disulfonation reaction complete while the reaction mixture is maintained within the cooled temperature range. A process for producing monopotassium 4,4'-diphenyldisulfonate is also disclosed, in which steps are taken of adding a sulfonating agent to diphenyl, then controlling the sulfuric acid concentration to 45 to 55%, and while the reaction mixture is heated to at least 140.degree. C., adding at least a stoichiometric amount of a potassium salt of an inorganic acid.
A process for producing 4,4'-diphenyldisulfonic acid comprising adding a sulfonating agent to molten diphenyl at a temperature of 130.degree.-145.degree. C., cooling the reaction mixture to 115.degree.-127.degree. C. when the crystallization of 4,4'-diphenyldisulfonic acid begins in said temperature range of 130.degree.-145.degree. C. and maintaining the reaction mixture in this temperature range of 115.degree.-127.degree. C. to complete the disulfonation reaction.
A process for producing monopotassium 4,4'-diphenyldisulfonate comprising adding a sulfonating agent to diphenyl, adding water to the reaction mixture to control the sulfuric acid concentration to 45-55% and adding at least a stoichiometric amount of a potassium salt of an inorganic acid and/or potassium hydroxide while the mixture is heated to at least 140.degree. C.
A process for producing monopotassium 4,4'-diphenyldisulfonate comprising adding a sulfonating agent to molten diphenyl at 130.degree.-145.degree. C., cooling the reaction mixture to 115.degree.-127.degree. C. when the crystallization of 4,4'-diphenyldisulfonic acid begins in said temperature range of 130.degree.-145.degree. C., maintaining the reaction mixture in this temperature range of 115.degree.-127.degree. C. to complete the disulfonation reaction, adding water to the reaction mixture to control the sulfuric acid concentration to 45-55% and adding at least a stoichiometric amount of a potassium salt of an inorganic acid and/or potassium hydroxide while the mixture is heated to at least 140.degree. C.
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