Hannah

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Introduction

Tautomers of Acetylacetone (C5H8O2)

  • Keto = ketone
  • Enol = alcohol
-may also be referred to as an alkenol
  • Usually the keto tautomer is favored
Figure 1:Basic reaction of keto- and enol- acetylacetone

Why Tautomerization Matters

  • Different solvents may change the equilibrium of the keto- and enol- forms
-Keto/enol equilibrium can be determined using proton NMR, as the spectra are different enough to distinguish between the tautomers
  • Tautomers in DNA replication have been hypothesized to contribute to mutagenic mispairings


F1.large.jpg

WebMO

  • All calculations were done using HF/6-31G(d) for geometry optimization
  • The products of the geometry optimizations were used to calculate the NMR spectra using the same basis sets

Keto Acetylacetone

Molecule (2).png

Proton NMR NmrKetoZoomed.png

Proton NMR shifts:File:NMR-Chemical-Shift-PPM-Range-and-Values-Table-.png

Enol Acetylacetone

Molecule.png

Proton NMR NmrEnol2.png

Proton NMR shifts:File:NMR-Chemical-Shift-PPM-Range-and-Values-Table-.png

N.B. Hydrogen bonding deshields the proton, further increasing the chemical shift