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Quinone‐Quinoneimine Tautomerism of 5, 8‐Bis(donor) substituted 1, 4‐Naphthoquinonoid Dyes
Author(s) -
Takagi Koichi,
Matsuoka Masaru,
Kubo Yuji,
Kitao Teijiro
Publication year - 1985
Publication title -
journal of the society of dyers and colourists
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.297
H-Index - 49
eISSN - 1478-4408
pISSN - 0037-9859
DOI - 10.1111/j.1478-4408.1985.tb01018.x
Subject(s) - tautomer , chemistry , quinone , absorption spectroscopy , photochemistry , absorption (acoustics) , computational chemistry , stereochemistry , materials science , physics , quantum mechanics , composite material
Quinone‐quinoneimine tautomerism of 5, 8‐bis(donor) substituted 1, 4‐naphthoquinones have been investigated by means of their visible absorption spectra. Tautomerism was found to be influenced mainly by the nature of the substituents and the polarity of the solvents; the equilibrium shifted to the quinone form in the more polar solvents. The quinone tautomer absorbed visible light at much longer wavelengths (about 160–180 nm) than did the quinoneimine tautomer. Isosbestic points of the tautomerism were observed. The calculated absorption maximum of each tautomer, obtained by means of the PPP MO method, was correlated with the observed values to predict the principal tautomer in solution.