CH610B Sophomore Organic II

Dr. Brian Pagenkopf

Introduction to Carbonyl Chemistry: Enolates and Enol Tautomers

The following is true for all carbonyl compounds with alpha hydrogens:

1. the alpha hydrogens of carbonyl compounds are acidic

2. enolates are stabilized by resonance

3. the carbonyl form and the enol form are called tautomers of each other

4. tautomerization can be base or acid catalyzed

Base catalyzed:

Acid catalyzed:

Compare the electron densities of acetaldehyde and its enolate tautomer, and its anionic enolate.

The haloform reaction: Even a carbon anion can be a leaving group if it’s stabilized enough, such as ^—:CCl₃.

Note that this is similar to what we saw with carbenes.