Vinyl sulfone dyes

Due to the relatively high reactivity of the vinyl sulfone group with water (residual moisture, air humidity), it is present in many commercial products in a protected form.

During the dyeing process under alkaline conditions, the vinyl sulfone group is released by an elimination reaction:

The oldest and most common intermediate is vinyl sulfone parabase ester (see image), an aniline substituted with a [2-(sulfooxy)ethyl]sulfonyl group.

[1] A further possibility is the condensation reaction of parabase ester with a chlorine or fluorotriazine residue, which in turn can be linked to any chromophore via a further amino group.

[2] If the vinyl sulfone group is introduced via a primary or secondary aliphatic amine, this is performed again by condensation with a halotriazine compound.