Resumen de Substituent Effects on Keto–Enol Equilibria Using NMR Spectroscopy
Kimberly A. Manbeck, Nicholas C. Boaz, Nathaniel C. Bair, Allix M. S. Sanders, Anderson L. Marsh
In this extension to a classic physical chemistry experiment, students record the proton nuclear magnetic resonance spectra of the β-diketones 2,4-pentanedione, 3-methyl-2,4-pentanedione, and 3-chloro-2,4-pentanedione to investigate the effect of substituents on keto–enol tautomerization equilibria. From the integrated intensities of keto and enol methyl proton peaks, students calculate the equilibrium constant for each 2,4-pentanedione. The students then use the effects of electron-donating and electron-withdrawing substituents to elucidate the nature of keto–enol equilibria.
