Question

How do you distinguish between chlorobenzene from benzyl chloride?

Answer 1

Chlorobenzene	Chloromethyl benzene
The chlorine atom is bonded to the aromatic carbon atom in Chlorobenzene.	The chlorine atom is bonded to the aliphatic carbon atom in Chloromethyl benzene.
The hybridization of carbon with which chlorine is attached is ${\mathrm{sp}}^2$	The hybridization of carbon to which chlorine is attached is ${\mathrm{sp}}^3$
Because the connected Chlorine atom is directly bonded to benzene and has a lone pair, it is difficult to break the Carbon-Chlorine bond.	Because the linked Chlorine atom is not directly attached to the ring, it is easier to break the Carbon-Chlorine bond.
There is no reaction when chlorobenzene is heated with alcoholic silver nitrate (${\mathrm{AgNO}}_3$) $\underset{\mathrm{Chlorobenzene}}{{\mathrm{C}}_6{\mathrm{H}}_5\mathrm{Cl}\left(\mathrm{l}\right)}+\underset{\mathrm{Silver}\mathrm{nitrate}}{{\mathrm{AgNO}}_3\left(\mathrm{l}\right)}\to \mathrm{No}\mathrm{reaction}$	When Chloromethyl benzene is treated with alcoholic silver nitrate$\mathrm{Ag}\left({\mathrm{NO}}_3\right)$, a white precipitate is produced. $\underset{\mathrm{Chloromethyl}\mathrm{benzene}}{{\mathrm{C}}_7{\mathrm{H}}_7\mathrm{Cl}\left(\mathrm{l}\right)}+\underset{\mathrm{Silver}\mathrm{nitrate}}{{\mathrm{AgNO}}_3\left(\mathrm{l}\right)}\to \underset{\mathrm{Benzyl}\mathrm{ethyl}\mathrm{ether}}{{\mathrm{C}}_9{\mathrm{H}}_{12}\mathrm{O}\left(\mathrm{l}\right)}+\underset{\mathrm{Silver}\mathrm{chloride}(\mathrm{White}\mathrm{ppt})}{\mathrm{AgCl}\left(\mathrm{l}\right)}+\underset{\mathrm{Nitric}\mathrm{acid}}{{\mathrm{HNO}}_3\left(\mathrm{l}\right)}$
Chlorobenzene (Phenyl chloride)	Chloromethyl benzene (α-Chlorotoluene Benzyl chloride)

Therefore, chlorobenzene and chloromethyl benzene can be distinguished on basis of hybridization, and the silver nitrate test.