Keto-enol and enol-enol tautomerism in trifluoromethyl-β-diketones |
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| Authors: | Joseph C Sloop Carl L Bumgardner W David Loehle Adam B Lewis |
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| Institution: | a Department of Chemistry and Life Science, United States Military Academy, 646 Swift Road, West Point, NY 10996, USA
b Department of Chemistry, North Carolina State University, P.O. Box 8204, Raleigh, NC 27695, USA |
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| Abstract: | The keto-enol (K?E) and enol-enol (E?E) equilibria of a variety of trifluoromethyl-β-diketones were investigated using 1H, 13C, 19F NMR spectroscopy, infrared spectroscopy and ultraviolet-visible spectrophotometry in nonpolar solvents. In general, NMR, IR and UV spectral evidence indicates that trifluoromethyl-β-diketones exist as mixtures of two chelated cis-enol forms in nonpolar media. Infrared spectroscopy and ultraviolet spectrophotometry show the E?E equilibrium lies in the direction of the enol form which maximizes conjugation in most cases. Exceptions are noted and discussed. |
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| Keywords: | β-Diketone Tautomerism Enol 19F NMR Chelated-OH Enone |
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