Reactivity, chemical selectivity and exhaust dyeing properties of dyes possessing a 2-chloro-4-methylthio-s-triazinyl reactive group

Several 2-chloro-s-triazinyl reactive dyes, each possessing a different substituent in the 4-position of the triazine ring, were synthesised, and their rates of hydrolysis and methanolysis were determined over a range of temperatures. The order of reactivity was 4-alkylthio > 4-methoxy > 4-dimethylamino. Unlike the 4-methylthio- and 4-dimethylamino-derivatives, in which the chlorine atom was replaced cleanly, both on hydrolysis and methanolysis, the 2-chloro-4-methoxy-s-triazine underwent concurrent displacement of both chlorine and methoxy substituents. The 2-chloro-4-methylthio-derivative displayed a high propensity to undergo methanolysis, rather than hydrolysis, in homogeneous solution and this preference for undergoing alcoholysis was mirrored in excellent fixation to cotton on exhaust dyeing.