Preparation of sulfonated triarylphosphines

A process for the preparation of a sulfonated triarylphosphine having the following general formula:

• ##STR4## wherein the radicals Ar are identical or different aryl radicals, the radicals X are identical or different straight or branched chain alkyl or alkoxy radicals having from 1 to 4 carbon atoms, halogen atoms, and the radicals hydroxy, nitrile, nitro, amino and amino substituted by straight or branched chain alkyl radicals having from 1 to 4 carbon atoms;
• M is hydrogen or an organic or inorganic cation such that the compound having the formula (I) is soluble in water;
• m.sub.1, m.sub.2 and m.sub.3 are integers which may be identical or different and which range from 0 to 5;
• and n.sub.1, n.sub.2 and n.sub.3 are integers which may be identical or different and which range from 0 to 3, with the proviso that at least one of n.sub.1, n.sub.2 and n.sub.3 is 1 or greater;
• comprising (i) sulfonating the aromatic moieties of a corresponding triarylphosphine starting material with an H.sub.2 SO.sub.4 /SO.sub.3 mixture;
• (ii) hydrolyzing the sulfonation reaction mixture to terminate said sulfonation reaction when same has attained the desired degree of sulfonation, thereby producing a hydrolysate rich in sulfuric acid and which comprises the product sulfonated triarylphosphine;
• (iii) next liquid/liquid extracting said hydrolysate with an organic phase comprising at least one phosphoric or diphosphoric, phosphonic or diphosphonic, phosphinic or diphosphinic ester, or phosphine oxide or diphosphine dioxide, or slightly water miscible or immiscible C.sub.4 -C.sub.12 alcohol, or sulfoxide extractant, whereby the sulfonated triarylphosphine (I) is extracted into said organic phase, (iv) separating the organic phase from the aqueous raffinate;
• (v) regenerating said organic phase with water when M is hydrogen or with an aqueous solution comprising M when M is other than hydrogen;
• and (vi) recovering an aqueous solution of said sulfonated triarylphosphine (I).