Mark Waner - Kinetic and Mechanistic Studies of the Deuterium Exchange in Classical Keto-Enol Tautomeric Equilibrium Reactions

Version 1

      Publication Details (including relevant citation   information):

      Nichols, M.A., Waner, M.J., J. Chem. Educ.,   2010, 87 (9), 952–955 (DOI: 10.1021/ed100292r).

      Abstract:

      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.

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