Synthesis and Electronic Spectra of Some Monoazo Disperse Dyes Derived from N‐Methylindoline

Several monoazo dyes suitable for transfer printing have been prepared from N-methylindoline and compared with the corresponding derivatives of N-methyl -12,3,4-tetrahy-droquinoline (kairoline). The presence of a five-membered terminal ring system leads to diminished π-interaction and results in modest hypsochromic and hypochromic shifts of the visible absorption band, relative to the analogous kairo-line derivatives, together with some deterioration in light-fastness properties on synthetic-polymer fibres.