NMR determination of the kinetics of deuterium exchange in acyclic hexanones

CHED 358

Amy Knutson and Thomas B. Malloy Jr., malloyt@stthom.edu. Department of Chemistry, University of St. Thomas, 3800 Montrose Blvd, Houston, TX 77006
We have used an Anasazi Eft-60 NMR spectrometer to study base-catalyzed deuterium exchange in the acyclic hexanones: 2-hexanone, 3-hexanone, 3-methyl-2-pentanone, 4-methyl-2-pentanone, 3-3-dimethyl-2-butanone and 2-methyl-3-pentanone. These offer a wide variety of rates depending on whether there is branching at the alpha position . In some cases, the disappearance of the protons in the alpha positions is followed directly. In others, coupling and line-shape changes of protons on adjacent carbons were used. These experiments have been adapted as undergraduate laboratory experiments and incoeporated ito our curriculum. Partial support for this work was provided by the National Science Foundation's Course, Curriculum, and Laboratory Improvement program under Award No. 0536648. The Welch Foundation is acknowledged for support.