Relationships between the structure of nitrodiphenylamine derived monoazo acid dyes and their spectroscopic and fastness properties

Fourteen monoazo acid dyes derived from 4-nitrodiphenylamine and 2-nitrodiphenylamine have been synthesized. Relationships between the position of nitro and sulphonic groups and the wavelength of the visible absorption band and also the lightfastness on polyamide fibres have been examined. It is suggested that the colour of the dyes and their lightfastness depend on the possibility of formation of intramolecular hydrogen bonding. The existence of such bonding was shown by the IR and UV-vis spectra of the investigated dyes and model derivatives of diphenylamine.