Nuclear magnetic resonance investigations of azo-hydrazone, acid-base equilibria of FD&C Yellow No. 6

Autor:	Saleh A. Turujman, Ely G. Mouchahoir, Mark D. Archer, Kathy W. Nielsen, Steven Prescott, Eugene P. Mazzola, William F. Reynolds, Sandra J. Bell, Julie N. Barrows, John E. Bailey, Mark Oliver
Rok vydání:	1996
Předmět:	chemistry.chemical_classification Nuclear magnetic resonance Base (chemistry) chemistry Proton Organic Chemistry Drug Discovery Potentiometric titration Analytical chemistry Hydrazone Resonance Biochemistry Tautomer
Zdroj:	Tetrahedron. 52:5691-5698
ISSN:	0040-4020
DOI:	10.1016/0040-4020(96)00205-0
Popis:	Azo-hydrazone, acid-base equilibria were examined for the water-soluble dye FD&C Yellow No. 6 (Y6), with the observation of dynamic NMR effects near, and at, pH 12, where the dye converts from a predominantly hydrazone tautomer (acidic to moderately basic pH) to a prevailing azo-anion resonance hybrid (high pH). Semilogarithmatic pH-13C chemical shift plots and a 2-bond, 15Nβ-13C8a coupling constants vs. pH relationship both indicate that the midpoint of the azo-hydrazone equilibrium occurs at ca. pH 12. Potentiometric titrations further indicate that thepKa of Y6 is ca. 12. These data suggest that the observed NMR line broadening is due to slow proton transfer between the hydrazone-NH and water. Download full-size image
Databáze:	OpenAIRE
Externí odkaz:	https://explore.openaire.eu/search/publication?articleId=doi_________::9f6e77c5a7dd2ea909e978aa4fd8257a https://doi.org/10.1016/0040-4020(96)00205-0 Zobrazit plný text záznamu Full Text from ScienceDirect