Question

Br\(_2\)/CS\(_2\) 

Hint:

The presence of the hydroxyl group makes phenol highly reactive to electrophilic substitution, resulting in tribromination in the ortho and para positions.

Answer 1

Phenol Bromination

Electrophilic substitution occurs when phenol reacts with bromine in carbon disulfide (CS₂). The hydroxyl group (-OH) on the phenol ring enhances reactivity at the ortho and para positions relative to itself.

Reaction:

Phenol and bromine in CS₂ react as follows: \[ \text{C}_6\text{H}_5\text{OH} + 3\text{Br}_2 \xrightarrow{\text{CS}_2} \text{C}_6\text{H}_2\text{Br}_3\text{OH} \] Bromine atoms substitute at the ortho and para positions relative to the hydroxyl group on the benzene ring.

Mechanism:

The electron-donating hydroxyl group (-OH) activates the benzene ring by increasing electron density at the ortho and para positions. This enhanced electron density makes the ring more susceptible to electrophilic attack by bromine (Br₂).

Major Product:

The primary product formed is 2,4,6-Tribromophenol, resulting from bromine substitution at the ortho and para positions adjacent to the hydroxyl group.

Conclusion:

Bromination of phenol with bromine in carbon disulfide (CS₂) yields 2,4,6-Tribromophenol as the main product. This outcome is attributed to the hydroxyl group's activating effect, which increases the benzene ring's susceptibility to electrophilic substitution.