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.