NMR structural study of the prototropic equilibrium in solution of schiff bases as model compounds

David Ortegón-Reyna; Cesar Garcías-Morales; Itzia Padilla-Martínez; Efren García-Báez; Armando Aríza-Castolo; A. Peraza-Campos; Francisco Martínez-Martínez

doi:10.3390/molecules19010459

NMR structural study of the prototropic equilibrium in solution of schiff bases as model compounds

David Ortegón-Reyna, Cesar Garcías-Morales, Itzia Padilla-Martínez, Efren García-Báez, Armando Aríza-Castolo, A. Peraza-Campos, Francisco Martínez-Martínez

Unidad Profesional Interdisciplinaria de Biotecnología (UPIBI)

Research output: Contribution to journal › Article › peer-review

17 Scopus citations

Abstract

An NMR titration method has been used to simultaneously measure the acid dissociation constant (pK_a) 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 (pK_a, 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.

Original language	English
Pages (from-to)	459-481
Number of pages	23
Journal	Molecules
Volume	19
Issue number	1
DOIs	https://doi.org/10.3390/molecules19010459
State	Published - Jan 2014

Keywords

D-diagram
NHO prototropic tautomerism
NMR titration
Schiff bases

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title = "NMR structural study of the prototropic equilibrium in solution of schiff bases as model compounds",

abstract = "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.",

keywords = "D-diagram, NHO prototropic tautomerism, NMR titration, Schiff bases",

author = "David Orteg{\'o}n-Reyna and Cesar Garc{\'i}as-Morales and Itzia Padilla-Mart{\'i}nez and Efren Garc{\'i}a-B{\'a}ez and Armando Ar{\'i}za-Castolo and A. Peraza-Campos and Francisco Mart{\'i}nez-Mart{\'i}nez",

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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 -

NMR structural study of the prototropic equilibrium in solution of schiff bases as model compounds

Abstract

Keywords

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