Question

Which of the following reagents can be used to distinguish chlorobenzene from chlorocyclohexane?

• A. $AgN{O}_3/C_2{H}_{5}OH$
• B. $Ag(N{H}_3{)}_{2}OH$
• C. No fusion, $HN{O}_3$, $AgN{O}_3$
• D. $B{r}_2/CC{l}_4$

Answer 1

The correct option is A $AgN{O}_3/C_2{H}_{5}OH$

Chlorocyclohexane behaves like an aliphatic halogen-substituted hydrocarbon and can therefore react with alcoholic $AgN{O}_3$.
Chlorobenzene does not react with $2\%$ ethanolic silver nitrate solution, but chlorocyclohexane reacts with $2\%$ ethanolic silver nitrate solution to give a white precipitate.
$\text{Chlorocyclohexane}\underset{EtOH}{\overset{AgN{O}_3}{\to }}\text{white ppt of AgCl}$

$\text{Chlorobenzene}\underset{EtOH}{\overset{AgN{O}_3}{\to }}\text{no reaction}$
It is due to different hybridisation of $C$ atom of $C-Cl$ bond. Chlorocyclohexane has $s{p}^3$ hybridisation whereas chlorobenzene has $s{p}^2$ therefore the latter compound does not show substitution reaction but the former compound does.