High affinity direct dyes containing cyclic amide
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The importance of aggregate formation in the application of substantive dyes has been convincingly explained.1 The ability of cyclic imide systems to form associates2-4 has been fully exploited in a study5 by synthesising direct dyes containing cyclic amide groups. The kind of direct azo dyes synthesised in the above study are shown in Chart 1. It has been shown that dyes containing cyclic imide system, e.g. imidazolone, quinoxilinedione or benzoxazolone show significant dye affinity to cellulose, even in cases where the dye has a relatively small molecular size.5 It has also been observed that, in some cases, monoazo dyes containing the imido-system exhaust well onto cellulose.5
