Among the amidoalkanesulfonic acid derivatives prepared by the above-described process or the like, unsaturated amido- and phenyl-substituted alkanesulfonic acid derivatives of the general formula ##STR5## where R4 and R5 are hydrogen or lower alkyl groups, and X is a hydrogen, alkali metal, alkaline earth metal or ammonium ion, such as 2-acrylamide-2-phenylpropanesulfonic acid, 2-acrylamido-2-phe