Tautomerism in 1-phenylazo-2-naphthols by use of nitrogen-14 nuclear magnetic resonance data

Fluorescence and Absorption Spectra of Phenylazopyrazolone Dyes

“…For the similarly structured phenylazonaphthols (II, III and IV, Fig. 1), a displaced equilibrium between the azo and quinonehydrazone tautomeric form is observed [5][6][7][8]. Bearing in mind Fischer's suggestion [6,9] that the quinonehydrazone struc ture is responsible for the emission of the phenyl azonaphthols, we found it of interest to study the fluorescence and absorption spectra of the phenyl azopyrazolone dyes and to observe the effect of substituents and solvents on their spectral prop erties.…”

α-(4-Methyl-2-nitrophenylhydrazono)acetoacetanilide, C17H16N4O4

“…(7) 0.7390 (4) 0.6628 (2) 0.2838 (6) 5.43 (9) C (8) 0.2895 (4) 0.6365 (2) 0.2948 (7) 4.27 (9) C (9) 0.2608 (4) The relative merits of the hydroxyazo (b) and hydrazone (c) tautomeric forms have been discussed in detail by Prendergrass, Paul & Curtin (1972), by Kuder (1972) and by Guggenberger & Teufer (1975), Prendergrass et al list the ranges of bond lengths to be expected for the two tautomers by comparison with those found in a series of closely related compounds, and our values generally lie intermediate between their two extremes. Berrie, Hampson, Longworth & Mathias (1968) have studied the problem by NMR spectroscopy and give quantitative estimates of the amounts of the tautomers. They concluded that a resonance hybrid would be the best representation of the formula.…”

Microwave-Assisted Synthesis of Phthalocyanine Zinc Complexes Derived from Aminotricyanobiphenyl-Based Azo Dyes

“…[17,[19][20] It is known that under certain conditions (low temperature, diluted acid) the products of reaction of diazotized amino benzonitriles with aniline and phenol are diazo ether [16] and triazenes, [21,22] respectively. Triazenes may be converted into azo compounds by heating in sulfuric acid.…”

“…[8] was prepared from phthalonitrile 14 (20 mg) in 70 % yield. (19) was synthesized from phthalonitrile 9 (20 mg) in 84 % yield (brown powder). IR (KBr) n cm …”