Question

Which of the following is correct regarding the enolic form of acetone?

• A. $8\sigma$ and 2 $\pi$ bonds
• B. $10\sigma$ and 1 $\pi$ bonds
• C. $9\sigma$ and 2 $\pi$ bonds
• D. $9\sigma$ and 1 $\pi$ bonds

Answer 1

The correct option is D $9\sigma$ and 1 $\pi$ bonds

Sigma bond is formed by the head on overlap of $s-s$ orbitals, $s-p$ and $p-p$ orbitals.
Single bond contains 1 $\sigma$ bond.
Double bond contains 1 $\sigma$ and 1 $\pi$ bond.
So, the enol form contains $1C-C$ double bond, $1C-C$ single bond $5C-H$ bond, $1C-O$ bond and $1O-H$ bond.
$\therefore$ Total 9 $\sigma$ bond and 1 $\pi$ bond.