Acid‐catalysed Hydrolysis of Type 3 Dye‐Fibre Bonds between Cellulose and Triazinyl Reactive Dyes

Abstract

The kinetics of the acid hydrolysis of Type 3 dyeings produced by the reaction of dichlorotriazinyl aminoazo dyes with cellulose have been studied at 40°C. A marked effect has been observed owing to what are believed to be localised pH effects, i.e. a non‐uniform distribution of hydrogen ions within the fibre phase owing to the localised charges on the dye molecules attached to the fibre. Variation of the ionic strength in the reaction medium does not affect the bimolecular rate constants for the hydrolysis, but brings about changes that can also be ascribed to pH effects in the fibre phase. There is evidence for two kinds of Type 3 dye‐fibre bonding, giving a very rapidly hydrolysed species, present in relatively low concentration, and a more stable species.