Question

How will you distinguish between the following pair of compounds?

Bromobenzene and benzyl bromide

Answer 1

	Bromobenzene	Benzyl bromide
Structure	Bromine is directly attached to the benzene ring (aryl halide).	Bromine is attached to the benzylic carbon (alkyl halide).
Reactivity	Less reactive; the strong C–Br bond due to sp2 hybridization causes resistance to nucleophilic substitution.	More reactive; weaker C–Br bond on sp3 hybridized benzylic carbon favors nucleophilic substitution.
Reaction with AgNO3	No or very slow reaction with aqueous silver nitrate; no immediate AgBr precipitate formation.	Reacts quickly with aqueous silver nitrate, producing white AgBr precipitate.
Reaction with aqueous KOH	Does not hydrolyze or react very slowly, forming phenol only under drastic conditions.	Easily hydrolyzes to benzyl alcohol under mild conditions.
Behavior under UV light	Does not undergo photochemical substitution readily.	Undergoes photochemical substitution readily.
Boiling Point	The boiling point of bromobenzene is around 156°C.	The boiling point of benzyl bromide is around 179°C.
Chemical Use	Used mainly for aromatic electrophilic substitution reactions in organic synthesis.	Used mainly as an alkylating agent in organic synthesis due to its higher reactivity.