Process for the manufacture of 4,4' dihydroxydiphenyl

A process for the preparation of 4,4' dihydroxydiphenyl alkali metal salt which comprises:

• (a) sulfonating diphenyl to form diphenydisulfonic acid;
• (b) reacting the diphenyldisulfonic acid with an inorganic compound to form an alkali metal diphenyldisulfonate;
• (c) fusing an alkali metal hydroxide with an initial charge of the alkali metal diphenyldisulfonate at a concentration of from 2 to about 10 moles of hydroxide per mole of sulfonate groups in the alkali metal disulfonate to form 4,4' dihydroxydiphenyl salt said fusion being free from additives to enhance fluidity;
• and
• (d) after most of the initial charge of alkali metal diphenyldisulfonate has reacted and when excess alkali metal hydroxide is present, adding additional alkali metal diphenyldisulfonate to the fusion to form additional 4,4' dihydroxydiphenyl salt by reaction with previously unreacted alkali metal hydroxide.

A process for the preparation of 4,4' dihydroxydiphenyl potassium salt comprising:

• (a) sulfonating diphenyl to form diphenyldisulfonic acid;
• (b) reacting the diphenyldisulfonic acid with a water soluble inorganic neutral potassium salt to precipitate potassium diphenyl 4,4' disulfonate;
• and
• (c) fusing potassium hydroxide with an initial charge of the potassium diphenyldisulfonate at a concentration of from about 2 to about 10 moles of hydroxide per mole of sulfonate groups in the potassium diphenyldisulfonate to form 4,4' dihydroxydiphenyl potassium salt said fusion being free from additives to enhance fluidity.