Question

Give at least one characteristic test which can distinguish between Chlorobenzene and n-hexyl chloride.

Answer 1

Hint: Chlorobenzene is a haloarene consisting of an aromatic ring. Whereas n-hexyl chloride is a haloalkane. Generally, haloalkanes are more reactive than haloarenes. Haloalkanes can be readily reacted with potassium hydroxide to yield n-hexyl alcohol.

Complete Step By Step Answer:
Aromatic compounds are the compounds consisting of cyclic, planar, conjugation of pi-electrons, and obeying Huckel’s rule.
Chlorobenzene is the chemical compound in which chlorine is attached to an aromatic ring. Aromatic compounds can be simply known as arenes. Thus, chlorobenzene is a haloarene.
n-hexyl chloride is an aliphatic haloalkane. The structure of n-hexyl chloride is $ C{H_3}C{H_2}C{H_2}C{H_2}C{H_2}C{H_2}Cl $
Generally, haloalkanes are more reactive than haloarenes. Thus, when the action of bases like potassium hydroxide is added to the haloalkanes, the halogen gets replaced by a hydroxide ion. Which is known as nucleophilic substitution reaction.
Hence, chlorobenzene on reaction with $ KOH $ , will not undergo the nucleophilic substitution and does not form benzyl alcohol. But n-hexyl chloride undergoes nucleophilic substitution or hydrolysis to form n-hexyl alcohol.
 $ C{H_3}C{H_2}C{H_2}C{H_2}C{H_2}C{H_2}Cl\xrightarrow{{aq.KOH}}C{H_3}C{H_2}C{H_2}C{H_2}C{H_2}C{H_2}OH $
Along with the formation of n-hexyl alcohol, there is a formation of potassium chloride with the molecular formula of $ KCl $ .
Thus, the action of aqueous potassium hydroxide makes the distinction between chlorobenzene and n-hexyl chloride.

Note:
Aromatic compounds and aliphatic compounds can be distinguished by heating them on a Bunsen burner. As aromatic compounds burn with a sooty flame and aliphatic compounds cannot give a sooty flame. Another difference is aromatic compounds undergo nitration when treated with nitric acid and concentrated acid gives a yellow color solution or compound.