Question

Benzene cannot be iodinated with $I_{2}$ directly. However, in presence of oxidants such as $HNO_{3}$ , iodination is possible. The electrophiles formed in the case is:

• A. $\left[I^{+}\right]$
• B. $\left[I^{-}\right]$
• C. $\left[\overset{\text{+δ}}{\text{I}} ...... \overset{\text{+δ}}{\text{O}} \text{H}_{\text{2}}\right]^{\text{+}}$
• D. $\left[\overset{- \text{δ}}{\text{I}} ...... \overset{- \text{δ}}{\text{O}} \text{H}_{\text{2}}\right]^{\text{+}}$

Answer 1

Answer: (A)

In the presence of oxidising agents such as $HNO_{3}$ direct, iodination of benzene is possible. The electrophiles formed in this case is $\left[I^{+}\right]$ .
Iodination reaction is reversible reaction. Nitric acid is oxidising agent which makes reaction irreversible.
$H ^{+}+ HNO _{3}+\frac{1}{2} I _{2} \rightarrow \underset{\text { Iodine cation }}{ I ^{+}}+ NO _{2}+ H _{2} O$