TY - JOUR
T1 - NMR structural study of the prototropic equilibrium in solution of schiff bases as model compounds
AU - Ortegón-Reyna, David
AU - Garcías-Morales, Cesar
AU - Padilla-Martínez, Itzia
AU - García-Báez, Efren
AU - Aríza-Castolo, Armando
AU - Peraza-Campos, A.
AU - Martínez-Martínez, Francisco
PY - 2014/1
Y1 - 2014/1
N2 - 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 d-diagram analysis and Perrin model data linearization.
AB - 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 d-diagram analysis and Perrin model data linearization.
KW - D-diagram
KW - NHO prototropic tautomerism
KW - NMR titration
KW - Schiff bases
UR - http://www.scopus.com/inward/record.url?scp=84893077664&partnerID=8YFLogxK
U2 - 10.3390/molecules19010459
DO - 10.3390/molecules19010459
M3 - Artículo
SN - 1420-3049
VL - 19
SP - 459
EP - 481
JO - Molecules
JF - Molecules
IS - 1
ER -