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Hydrogen Bonding Using NMR: A New Look at the 2,4-Pentanedione Keto-Enol Tautomer Experiment

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Theresa Julia Zielinski

Department of Chemistry, Medical Technology, and Physics, Monmouth University, West Long Branch, NJ 07764

Alexander Grushow

Department of Chemistry and Biochemistry, Rider University, Lawrenceville, NJ 08648-3001

J. Chem. Educ., 2002, 79 (6), p 707

DOI: 10.1021/ed079p707

Publication Date (Web): June 1, 2002

Abstract

A number of modifications to the standard keto–enol experiment in the physical chemistry laboratory are suggested for using modern NMR instruments now available in many chemistry departments. These modifications include sample preparation using a deuterated solvent for FT–NMR frequency locking, in-depth analysis of a proton spectrum acquired with a medium field (~300 MHz) NMR, examination of the temperature dependence of equilibrium processes, and multinuclear investigations. Remote access to the instrument and subsequent data analysis facilitated by the Internet are discussed. These methods permit students to learn about a wide variety of concepts within an integrated single-experiment design. We include student data in our analysis and an overview of possible extensions to the experiment.

Keywords (Audience):

Upper-Division Undergraduate

Keywords (Domain):

Physical Chemistry

Keywords (Pedagogy):

Hands-On Learning / Manipulatives

Keywords (Subject):

Equilibrium

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Citing Articles

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This article has been cited by 8 ACS Journal articles (5 most recent appear below).

Substituent Effects on Keto–Enol Equilibria Using NMR Spectroscopy
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Journal of Chemical Education2011 Article ASAP
- Substituent Effects on Keto–Enol Equilibria Using NMR Spectroscopy
  Kimberly A. Manbeck, Nicholas C. Boaz, Nathaniel C. Bair, Allix M. S. Sanders, and Anderson L. Marsh
  Journal of Chemical Education2011 Article ASAP
  In this extension to a classic physical chemistry experiment, students record the proton nuclear magnetic resonance spectra of the β-diketones 2,4-pentanedione, 3-methyl-2,4-pentanedione, and 3-chloro-2,4-pentanedione to investigate the effect of ...
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Kinetics of Neuraminidase Action on Glycoproteins by One- and Two-Dimensional NMR
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Journal of Chemical Education2011 88 (1), 95-97
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Kinetic and Mechanistic Studies of the Deuterium Exchange in Classical Keto−Enol Tautomeric Equilibrium Reactions
Michael A. Nichols and Mark J. Waner
Journal of Chemical Education2010 87 (9), 952-955
- Kinetic and Mechanistic Studies of the Deuterium Exchange in Classical Keto−Enol Tautomeric Equilibrium Reactions
  Michael A. Nichols and Mark J. Waner
  Journal of Chemical Education2010 87 (9), 952-955
  An extension of the classic keto−enol tautomerization of β-dicarbonyl compounds into a kinetic analysis of deuterium exchange is presented. It is shown that acetylacetone and ethyl acetoacetate undergo nearly complete deuterium exchange of the α-methylene ...
  Abstract | Full Text HTML | Hi-Res PDF | PDF w/ Links
Keto–Enol Equilibrium from NMR Data: A Closer Look at the Laboratory Experiment
Andrei B. Koudriavtsev and Wolfgang Linert
Journal of Chemical Education2009 86 (10), 1234
- Keto–Enol Equilibrium from NMR Data: A Closer Look at the Laboratory Experiment
  Andrei B. Koudriavtsev and Wolfgang Linert
  Journal of Chemical Education2009 86 (10), 1234
  Experimental setup and evaluation of equilibrium and kinetic data on the keto–enol transformation in acetylacetone and similar β-diketones has been discussed in relation to a physicochemical laboratory NMR experiment. The slow kinetics of this ...
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Acid-Catalyzed Enolization of β-Tetralone
Brahmadeo Dewprashad , Anthony Nesturi and Joel Urena
Journal of Chemical Education2008 85 (6), 829
- Acid-Catalyzed Enolization of β-Tetralone
  Brahmadeo Dewprashad , Anthony Nesturi and Joel Urena
  Journal of Chemical Education2008 85 (6), 829
  This experiment allows students to use 1H NMR to directly compare the relative initial rates of substitution of the benzylic and non-benzylic α hydrogens of β-tetralone and correlate their findings with the predictions made by resonance theory. The ...
  Abstract | Hi-Res PDF | PDF w/ Links