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:

VS dyes are widely used for exhaust dyeing, cold pad batch process and also in automated batch wise dyeing machines. These are also used for printing by one phase or two phase application method. The range offers very good light and wash fastness. Excellent white effect on dyed grounds by discharge and resist printing method. It has high stability in dry state and neutral solution.

These dyes are of particular interest in the dyeing and printing of cellulosic fibres, such as Cotton, Linen, Viscose, Cuprammonium and Polynosic rayons.