Question

Compare the enol content of the given molecules and arrange them in decreasing order.

• A. (I) > (II) > (III) > (IV)
• B. (IV) > (III) > (II) > (I)
• C. (III) > (IV) > (II) > (I)
• D. (I) > (II) > (IV) > (III)

Answer 1

The correct option is D (I) > (II) > (IV) > (III)

After the removal of $H^{+}$ (acidic- Hydrogen) from the compounds, the carbanion is formed.


$\text{Enol percent}\propto \text{Stability of carbanion}$
$N{O}_2$ is the strongest electron withdrawing group so it stabilise the carbanion more than the others.
$Cl$ shows -I effect and stabilise the carbanion formed.
Carbanion of (IV) is not stabilised by any group.
Carbanion of (III) is destabilised by +I and +H effect of methyl group. Thus, the order of stability of carbanion formed is
(I) > (II) > (IV) > (III)
Order of enol content is
(I) > (II) > (IV) > (III)