15N, 13C and 1H NMR spectra and azo-hydrazone tautomerism of some phenylazo compounds derived from 1,3- and 1,5-dihydroxynaphthalene

Two series of dyes have been prepared by coupling conventional carbocyclic and heterocyclic diazo components to N-beta-methoxycarbonylethyl-1,2,3,4tetrahydroquinoline and N-beta-methoxycarbonylethylindoline. The spectroscopic characteristics of the dyes were consistent with theoretical expectations as well as literature data for analogous structures derived from tetrahydroquinoline and indoline couplers. No clear-cut structure¯light fastness relationships were identified within either series, although a general correlation between ratings for these and previouslyreported sets of related dyes was observed. Since alkoxycarbonylalkyl functions have been exploited as a means of conferring alkali-clearability on commercial colorants, several members of the synthesised range of dyes were examined for signs of this behaviour; comparison with isomeric N-acetoxyethyl analogues indicated that the presence of a single N-betA-methoxycarbonylethyl residue was not sufficient to bring about a significant effect.