Next Article in Journal
Wine by-Products: Phenolic Characterization and Antioxidant Activity Evaluation of Grapes and Grape Pomaces from Six Different French Grape Varieties
Previous Article in Journal
Antioxidant Properties and Hyphenated HPLC-PDA-MS Profiling of Chilean Pica Mango Fruits (Mangifera indica L. Cv. piqueño)
Article Menu

Export Article

Open AccessArticle
Molecules 2014, 19(1), 459-481; doi:10.3390/molecules19010459

NMR Structural Study of the Prototropic Equilibrium in Solution of Schiff Bases as Model Compounds

Laboratorio de Posgrado, Facultad de Ciencias Químicas, Universidad de Colima, Km 9 Carretera Colima-Coquimatlán, Colima 28400, Mexico
Departamento de Química, Centro de Investigación y Estudios Avanzados del Instituto Politécnico Nacional, Av. IPN 2508, San Pedro Zacatenco 07360, México D. F., Mexico
Departamento de Ciencias Básicas, Unidad Profesional Interdisciplinaria de Biotecnología del Instituto Politécnico Nacional, Av. Acueducto s/n Barrio la Laguna Ticomán, México D. F. 07340, Mexico
Author to whom correspondence should be addressed.
Received: 28 October 2013 / Revised: 12 December 2013 / Accepted: 13 December 2013 / Published: 31 December 2013
View Full-Text   |   Download PDF [2860 KB, uploaded 18 June 2014]   |  


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. View Full-Text
Keywords: Schiff bases; NHO prototropic tautomerism; NMR titration; δ-diagram Schiff bases; NHO prototropic tautomerism; NMR titration; δ-diagram

Figure 1

This is an open access article distributed under the Creative Commons Attribution License (CC BY 3.0).

Scifeed alert for new publications

Never miss any articles matching your research from any publisher
  • Get alerts for new papers matching your research
  • Find out the new papers from selected authors
  • Updated daily for 49'000+ journals and 6000+ publishers
  • Define your Scifeed now

SciFeed Share & Cite This Article

MDPI and ACS Style

Ortegón-Reyna, D.; Garcías-Morales, C.; Padilla-Martínez, I.; García-Báez, E.; Aríza-Castolo, A.; Peraza-Campos, A.; Martínez-Martínez, F. NMR Structural Study of the Prototropic Equilibrium in Solution of Schiff Bases as Model Compounds. Molecules 2014, 19, 459-481.

Show more citation formats Show less citations formats

Related Articles

Article Metrics

Article Access Statistics



[Return to top]
Molecules EISSN 1420-3049 Published by MDPI AG, Basel, Switzerland RSS E-Mail Table of Contents Alert
Back to Top