Process for the preparation of sulphonated distyryl-biphenyl compounds

A process for the preparation of sulphonated distyryl-biphenyl compounds of formula:

• in which R1 and R2, independently, are hydrogen, C1-C5-alkyl, C1-C5-alkoxy or halogen, and M represents Li, K, an alkaline earth metal, ammonium, a mono-, di- or trialkylammonium or a tetraalkylammonium, all containing 1-4 carbon atoms in each alkyl group;
• a mono-, di- or tri (C2-C4)alkanolammonium, morpholinium, piperidinium or pyrrolidinium characterized by, firstly, reacting a compound of formula
• with a di- or trialkylamine containing 6-12 carbon atoms in each alkyl group, in a two-phase system consisting of strong aqueous mineral acid and a water immiscible organic solvent and, secondly, reacting the resulting lypophilic ammonium salt with LiOH, KOH, an alkaline earth metal hydroxide, ammonia, a mono-, di- or trialkylamine or a tetraalkylammonium hydroxide, all containing 1-4 carbon atoms in each alkyl group;
• a mono-, di- or tri(C2-C4)alkanolamine, morpholine, piperidine or pyrrolidine.