Definition of Reactive Dye

Reactive Dye

A dye, which is capable of reacting chemically with a substrate to form a covalent dye substrate linkage, is known as reactive dye.

Here the dye contains a reactive group and this reactive group makes covalent bond with the fibre polymer and act as an integral part of fibre. This covalent bond is formed between the dye molecules and the terminal –OH (hydroxyl) group of cellulose fibres on between the dye molecules and the terminal –NH₂ (amino) group of poly-amide or wool fibres.

Reaction:

D-SO₂-CH₂-CH₂-OSO₃Na +OH-cell     =>      D-SO₂-CH₂-CH₂-O-cell + NaHSO₃

D-SO₂-CH₂-CH₂-OSO₃Na + NH₂- wool   =>    D-SO₂-CH₂-CH₂-NH-Wool + NaHSO₃

Here, D= dye part.

   Wool = wool polymer.

      Cell = cellulosic polymer.