Triazinyl reactive dyes for the exhaust dyeing of cotton: Influence of the oxido group on the reactivity of chloro and m-carboxypyridinium leaving groups

A series of four triazinyl reactive dyes have been applied to cotton by exhaust dyeing in alkaline media. Two of the dyes employed o-toluidine as the reactivity modifying group, with either a chlorine or a nicotinic acid leaving group, and the other two used the same leaving groups but with an oxido group as the reactivity modifier. The dye containing the combination of a chlorine leaving group and an oxido reactivity modifying group (dye IV) proved greatly inferior in dyeing performance to that of the other combinations studied in the series. Dyeing at a higher salt level, to correct for the low substantivity of dye (IV), and at a higher temperature, furnished only a marginal improvement in visual colour yield indicating lack of reactivity to be the problem. The low reactivity of dye (IV) was confirmed by computational analysis.