Question

The decreasing order of enol percent of the given compounds is

• A. $a>b>c$
• B. $c>b>a$
• C. $a>c>b$
• D. $b>c>a$

Answer 1

The correct option is C $a>c>b$

In Keto-enol tautomerism, delocalisation takes place between a >C=O group and an alpha H where the equilibrium lies between a keto form and an enol form.
Bond strength of $C-D$ is greater than $C-H$.
Therefore,$C-D$ will not break easily.
Thus, compound (b) does not form enol readily. Hence, it will have least enol content.
Since, compound (a) does not have a $C-D$ bond it will undergo enolisation effectively and have greater enol content compared to others.
Hence, the decreasing order of enol percent is
$a>c>b$