Synthesis and Electronic Spectra of some Disperse Dyes Derived from 8-Phenylazolilolidine

Absorption spectra of 8–phenylazolilolidine and eleven para–substituted derivatives have been determined for solutions in ethanol and ethanolic hydrogen chloride. The pronounced bathochromic shifts and increases in intensity of the first band observed for the corresponding julolidine analogues, relative to the appropriate derivatives of 4–dimethylaminoazobenzene, are somewhat reduced with the lilolidine compounds. The difference in frequency between the absorption maxima of the dyes and their azonium salts correlates well (r=0. 993) with the unmodified Hammett values of the substituents. The lilolidine dyes are suitable for transfer printing, but show poor light–fastness properties on synthetic–polymer fibres.