Study into the cold pad‐batch application of monochloro‐s‐triazinyl and m‐carboxypyridinium‐s‐triazinyl reactive dyes bearing various “second‐leg” N‐substituents

A series of monochloro‐s‐triazinyl (MCT) and related m‐carboxypyridinium‐s‐triazinyl (nicotinic acid [NTR]) reactive dyes based on the same red chromophore and bearing –NHCN, –OCH3, –N(CH3)SO2CH3, –N‐methylphenyl and –OH “second‐leg” substituents were evaluated in cold pad‐batch dyeing. It was found that both the MCT and NTR dyes containing a cyanoamino second‐leg substituent displayed a superior technical performance to the dyes bearing methoxy, N‐methyl(methylsulphonyl)amino, hydroxyl and N‐methylaniline substituents. The results suggest that these technical benefits of dyeing are derived from the smaller molecule size and electronic effect of the cyanoamino group compared with the other second‐leg substituents commonly used in both MCT and NTR reactive dye synthesis. Indeed, the use of the cyanoamino second leg on the studied red NTR reactive dyes offered a combination of short batch time, high fixation efficiency, good build‐up properties and good wet fastness properties.