Hannah

Introduction

Tautomers of Acetylacetone (C₅H₈O₂)

-Keto = ketone

-Enol = alcohol

-may also be referred to as an alkenol

-Usually the keto tautomer is favored

-The basic reaction

Why Tautomerization Matters

-Different solvents may change the equilibrium of the keto- and enol- forms

-Tautomers in DNA replication have been hypothesized to contribute to mutagenic mispairings

-"whereas in RNA, minor tautomeric forms have been proposed to enhance the structural and functional diversity of RNA enzymes and aptamers" (https://rnajournal.cshlp.org/content/21/1/1.full.html)

WebMO

-All calculations were done using HF/6-31G(d)

Keto Acetylacetone

Proton NMR

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

Enol Acetylacetone

Proton NMR

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