Substituted diphosphines and a process for their preparation

A water-insoluble compound of the formula ##STR7## wherein R.sup.1 is selected from the group consisting of carboxylate (COO.sup.-) sulfonate (SO.sub.3.sup.-), phosphonate (PO.sub.3.sup.2-) and 2-aminoethanebisphosphonate, R.sup.2 is selected from the group consisting of straight-chain alkylene of 1 to 8 carbon atoms, an oxygen-containing alkylene of 2 to 6 carbon atoms, cycloalkylene of 3 to 10 carbon atoms and a member of the formulae II, III, IV or V ##STR8## a, b, c, d, e, f, g, h, k and l are individually 0 or 1, where at least one of a, b, c, d, e, f, g, h, k or l has to be equal to 1, x(s) are individually 0 to 1, y is an integer of 1 to 24, R.sup.3 and R.sup.4 are individually selected from the group consisting of optionally substituted alkyl of 4 to 26 carbon atoms, aryl of 6 to 10 carbon atoms, cycloalkyl of 6 to 10 carbon atoms and benzyl and R.sup.3 can also be hydrogen.