N‐Alkylbetaines in Wool Dyeing

The influence of N‐alkylbetaines, with alkyl chain lengths from eight to 18 carbon atoms, on the dyeing of wool with acid dyes has been studied. In the first part of the study the presence of N‐alkylbetaines was found to cause spectral changes of the dye in solution, and two clearly differentiated dissociation stages have been observed. These represent the formation of dye‐betaine complexes and the solubilisation of these complexes in the betaine micelles. The second part of the study examined how the presence of betaines influenced dyeing kinetics. Generally N‐alkylbetaines were found to increase the rate of dyeing, the type and amount of betaine present being important factors.