Kinetic and Mechanistic Studies of the Deuterium Exchange in Classical Keto−Enol Tautomeric Equilibrium Reactions
-
Michael A. Nichols [1] ; Mark J. Waner [1]
-
[1] University Heights, Ohio
-
- Localización: Journal of chemical education, ISSN 0021-9584, Vol. 87, Nº 9 (September), 2010, págs. 952-955
- Idioma: inglés
- Texto completo no disponible (Saber más ...)
-
Resumen
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 carbon when dissolved in methanol-d4. The extent of deuteration may be monitored via NMR spectroscopy as a function of time. A mechanism for deuterium exchange is presented and shown to be consistent with a consecutive first-order process. The data for acetylacetone are consistent with steady-state kinetics, whereas those of ethyl acetoacetate illustrate nonsteady-state behavior, offering an accessible example where students might collect and analyze real data to examine the applicability of the steady-state approximation.
