NMR structural study of the prototropic equilibrium in solution of Schiff bases as model compounds.
Molecules
; 19(1): 459-81, 2013 Dec 31.
Article
em En
| MEDLINE
| ID: mdl-24384925
An NMR titration method has been used to simultaneously measure the acid dissociation constant (pKa) and the intramolecular NHO prototropic constant ΔKNHO on a set of Schiff bases. The model compounds were synthesized from benzylamine and substituted ortho-hydroxyaldehydes, appropriately substituted with electron-donating and electron-withdrawing groups to modulate the acidity of the intramolecular NHO hydrogen bond. The structure in solution was established by 1H-, 13C- and 15N-NMR spectroscopy. The physicochemical parameters of the intramolecular NHO hydrogen bond (pKa, ΔKNHO and ΔΔG°) were obtained from 1H-NMR titration data and pH measurements. The Henderson-Hasselbalch data analysis indicated that the systems are weakly acidic, and the predominant NHO equilibrium was established using Polster-Lachmann δ-diagram analysis and Perrin model data linearization.
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Bases de Schiff
/
Ressonância Magnética Nuclear Biomolecular
Idioma:
En
Revista:
Molecules
Assunto da revista:
BIOLOGIA
Ano de publicação:
2013
Tipo de documento:
Article
País de afiliação:
México
País de publicação:
Suíça