Prev. Article Next Article Table of Contents

Article

Deuterium Exchange in Ethyl Acetoacetate: An Undergraduate GC–MS Experiment

Your current credentials do not allow retrieval of the full text.

Purchase the full-text

PDF/HTML,
figures/images,
references and tables,
(where available)

C.D. Heinson , J. M. Williams , W. N. Tinnerman and T. B. Malloy

Department of Chemistry, University of St. Thomas, Houston, TX 77006

J. Chem. Educ., 2005, 82 (5), p 787

DOI: 10.1021/ed082p787

Publication Date (Web): May 1, 2005

Section:

History, Education, and Documentation

Abstract

A simple experiment involving deuterium exchange of the enolizable protons in ethyl acetoacetate followed by GC–MS has been developed. The principles demonstrated are the use of stable isotopes, keto–enol tautomerism, base catalysis, and the use of specific reagents to minimize or nullify side reactions. The changes in mass of specific fragment ions, as well as that of the molecular ions are indicative of the course of the reaction and illustrative of the fragmentation pathways. The acidity of the methylene hydrogens of the acetoacetate moiety is exploited in the acetoacetic ester synthesis of alkyl-substituted acetones. These readily exchange under very mild conditions. More challenging is to exchange all five enolizable hydrogens. Use of increasingly severe reaction conditions leads to side reactions, such as deuterolysis of the ester portion if D₂O is used. The solution was to use ethanol O–d as the source of deuterium and KOD for the base for the exchange reaction and moderate heat. The role of ethanol O–d in nullifying the deuterolysis is demonstrated by determining that trans-esterification of methyl acetoacetate to the ethyl ester occurs as well as deuterium exchange of the five acetoacetate hydrogens.

Keywords (Audience):

Upper-Division Undergraduate

Keywords (Domain):

Organic Chemistry

Keywords (Pedagogy):

Hands-On Learning / Manipulatives

Keywords (Subject):

Catalysis

View: Hi-Res PDF | PDF w/ Links

Citing Articles

View all 1 citing articles

Citation data is made available by participants in CrossRef's Cited-by Linking service. For a more comprehensive list of citations to this article, users are encouraged to perform a search in SciFinder.

This article has been cited by 1 ACS Journal articles (1 most recent appear below).

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