The Covalent Reactions of Primary Amino Side‐chains and Disulphide Bonds in Wool Keratin

Abstract

Previous work on the reactions of different types of reactive dyes with wool is reassessed and new jindings presented. The decrease in reactivity of basic wool side chains to reaction with 1:fluoro:2:4 dinitrobenzene after wool has been dyed with acidic or reactive dyes is further investigated. New and previous correction factors measuring the extent of this inactivation are compared. Using such corrections, the extent of actual covalent binding of reactive dyes to basic wool side chains is determined. Applying these corrections gives reasonable stoichiometry in the dye‐fibre reaction. The extent of reaction of thiols, basic and hydroxyl groups in wool with five reactive dyes of different classes has been measured, and compared for two dyeing methods (long‐liquor and urea pad‐batch). The differences and similarities in the extent and type of reaction of the dyes with the fibre sites, using the two methods of application, is discussed. The role of disulphide degradation in reactive dyeing is further investigated. The effect of alkaline treatments on the fixation of reactive dyes, and the availability of wool lysine side‐chains for reaction (in the urea pad‐batch dyeing system) is reported upon.