Vinyl sulfone dyes

Vinyl sulfone dyes are reactive dyes comprising a vinyl sulfone group as reactive group (a fiber-bonding site of the reactive dye, "reactive hook"). 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. For protection, an ethylsulfonyl group is substituted with a leaving group. During the dyeing process under alkaline conditions, the vinyl sulfone group is released by an elimination reaction:


Formation of the vinyl sulfone group by alkaline elimination. R= alkyl or aryl radical, X=-OSO3H, -Cl