SPECTRAL CHARACTERIZATION OF SOME PHENYLAZODIHYDROXY NAPHTHALENE DERIVATIVES

A series of azo dyes namely: 4-phenylazo-1,3-dihydroxynaphthalene 1,4- phenylazo-1,5-dihydroxynaphthalene 2, 1-phenylazo-2,B-dihydroxynaphtha lene 3, 1-phenylazo-2,3-dihydroxynaphthalene 4 and 1-phenylazo-2,7-dih ydroxy-naphthalene 5 have been prepared and their UV, IR, NMR and mass spectra are recorded. The spectra have been analysed to give a comple te picture of the hydroxyazo-quinone hydrazone tautomerism present in these class of compounds. It is found that dyes 1, 2 and 4 exhibit qui none hydrazone tautomerism while dyes 3 and 5 exist as a mixture of hy droxyazo and quinone hydrazone tautomers. The change due to a second h ydroxyl group in the naphthalene moiety is compared with azonaphthols. The fragmentation process in the mass spectra displays C-N and -N=N- cleavage and indicated that the two tautomers are present except in dy e 2 which exhibits a quinone hydrazone form.