Question

When nitrobenzene is treated with $B{r}_2$ in the presence of $FeB{r}_3$, the major product formed is m-bromonitrobenzene. Choose the statement(s) which is/are related to obtain meta isomer.

• A. Electron density on meta carbon is more than that on ortho or para carbons.
• B. Aromaticity is lost when $B{r}^{+}$ attacks at the ortho or para positions and not at meta position.
• C. Intermediate carbocation formed after initial attack of $B{r}^{+}$ at the meta position is least destabilized.
• D. $H^{+}$ ion is easily removed to regain aromaticity from meta position than from ortho or para position.

Answer 1

Answer: (A), (C)

The correct options are
A Electron density on meta carbon is more than that on ortho or para carbons.
C Intermediate carbocation formed after initial attack of $B{r}^{+}$ at the meta position is least destabilized.

Nitro group is an electron withdrawing and deactivating group towards electrophilic attack. It reduces the electron density from ortho and para positions to a greater extent than from meta positions. Hence, electron density on meta carbon is more than that on ortho or para carbons. Due to this, the intermediate carbocation formed after initial attack of $B{r}^{+}$ at the meta position is least destabilized.