These sulfonated condensation products preferably have the formula ##STR15## in which X is a direct bond or oxygen, A is the radical of an aromatic compound which is bonded to the methylene group by means of a ring carbon atom, M is hydrogen or a cation, e.g. an alkali metal, an alkaline earth metal or an ammonium group, and n2 and p are each a number from 1 to 4. n2 and p are preferably 1 or 2, b