Ionization and Tautomerism of Fluorescein, Rhodamine B, N,N-Diethylrhodol and Related Dyes in Mixed and Nonaqueous Solvents
1994; Elsevier BV; Volume: 24; Issue: 1 Linguagem: Inglês
10.1016/0143-7208(94)87009-8
ISSN1873-3743
AutoresNikolay O. Mchedlov‐Petrossyan, Valentina I. Kukhtik, В. И. Алексеева,
Tópico(s)Chemical Reaction Mechanisms
ResumoThe protolytic equilibria of Fluorescein, Rhodamine B and of asymmetrical amino-oxyanthene dye, N,N-diethylrhodol (a 'hybrid' of Rhodamine B and Fluorescein) were studied in aqueous DMSO and EtOH (91 wt% of organic cosolvent). The pKa values of these dyes, as well as of related substances were determined. On the basis of the visible absorption spectra in various solvents conclusions are made about the tautomerism in the dye molecule. The values of the tautomeric equilibrium constants and of the microscopic ionization constants were obtained. Some new data on the tautomerism of oxyxanthene monoanions in methanol are presented.
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