| abstract |
Special sulfinic acid derivatives of the formula (I) wherein M is a hydrogen atom or one equivalent of a mono- or polyvalent cation, Y represents a hydroxy group, an -NH 2 group or a group -NR 3 R 4 , wherein R 3 and R 4 independently of one another represent a (C 1 to C 6 ) -alkyl group, a (C 2 to C 6 ) -alkylene group , a (C 1 to C 6 ) -hydroxyalkyl group, a (C 2 to C 6 ) -polyhydroxylalkyl group, an aryl group or an aryl (C 1 to C 6 ) -alkyl group, R 1 is a 1,2-dihydroxyethyl group, a 1,2,3-trihydroxypropyl group, a 1,2,3,4-tetrahydroxybutyl group or a 1,2,3,4,5-pentahydroxypentyl group and R 2 is a hydrogen atom or a hydroxymethyl group, allow permanent discoloration of colored substrates without darkening of the decolorized substrate. The substrate structure is spared during the decolorization process. |