# What is the relationship between ketone and enol?

Nov 28, 2016

An enol derivative, typically, $R C \left(- O H\right) = C {H}_{2}$, derives from a carbonyl species. It may be deprotonated to give the $\text{enolate}$, $R C \left(- {O}^{-}\right) = C {H}_{2}$.

#### Explanation:

Carbonyl compounds typically undergo enol/ketone tautomerism, i.e. for acetone we can write:

${H}_{3} C - C \left(= O\right) C {H}_{3} r i g h t \le f t h a r p \infty n s {H}_{2} C = C \left(- O H\right) C {H}_{3}$

This equilibrium lies strongly to the left, but it may be manipulated.

The alcohol, $\text{the enol}$, contains a protic hydrogen, that can be potentially deprotonated to give an enolate, the anion:

${H}_{2} C = C \left(- O H\right) C {H}_{3} + \text{Base"rightleftharpoonsH_2C=C(-O^(-))CH_3+"Base"""^(-)H""^(+)}$

The enolate anion itself is conceived to be in equilibrium with the carbanion:

${H}_{2} C = C \left(- {O}^{-}\right) C {H}_{3} r i g h t \le f t h a r p \infty n s {H}_{2}^{-} C - C \left(= O\right) C {H}_{3}$.

This $\text{carbanion/enolate}$ equilibrium is the classic strategy employed in $C - C$ bond formation. Carbanions may be formed from malonic acid derivatives, and ethylacetoacetate. For more details consult your organic text.