(Solved): Experiment : NMR determination of keto-enol equilibrium constants Acetyl Acetone in CCl4 399.65 MHz ...

Acetyl Acetone in CCl4 399.65 MHz 0.05 ml: 0.5 ml CC14 B D OH H- ppm D H= ppm 2207.64 2.236 1443.85 3.612 5.524 893.80 2.044 816.89 Int. 33.7% A 9% B 36% C 100% D Calculations The protons of the keto and enol forms are in distinctly different chemical environments that can be distinguished via NMR spectroscopy (CH peak in the enol form with the CH? peak in the keto form). The relative strength of the NMR signals will be proportional to the concentration of each different form. Thus, the equilibrium constant for the reaction can be determined by measuring the integrated NMR signals for the enol vinyl and keto methylene protons of each form. The equilibrium constant for the tautomerization reaction can be written as: K= [enol]/[keto] % [enol] = (total(enol)/total enol + total keto/2) x100 % [keto] = 100-% [enol] 1-Mention the spin coupling type for each peak and state the reason for your answer. 2-Calculate the equilibrium constant for the keto-enol forms of acetylacetone in CCl4