Question

The reactivity of ethyl chloride
A. More or less equal to that of benzyl chloride
B. More than that of benzyl chloride
C. More or less equal to that of chlorobenzene
D. Less than chlorobenzene

Answer 1

Hint: We know, ethyl chloride is a haloalkane which is chemically written by the formula of \[{{\rm{C}}_{\rm{2}}}{{\rm{H}}_{\rm{5}}}{\rm{Cl}}\]. For reactivity comparison of the given compounds, we have to consider the \[{S_N}^2\] reaction of these compounds.

Complete Step by Step Solution:
Let's understand what an \[{S_N}^2\]reaction is. In this reaction, the molecule is attacked by a nucleophile from the back side. Therefore, compounds containing the bulky groups show less reactivity towards \[{S_N}^2\]reaction.
Here, the given compounds are, ethyl chloride, benzyl chloride and chlorobenzene. Let's draw the structures of these compounds.


Let's compare the reactivity of benzyl chloride and ethyl chloride. In benzyl chloride, there is the presence of the bulky group. So, its reactivity is less than ethyl chloride. So, option B is right and option A is wrong.

Now, we will compare the reactivity of benzyl chloride and chlorobenzene. In chlorobenzene, due to resonance, the C-Cl bond acquires a double bond character. Therefore, the breaking of the C-Cl bond is difficult. Therefore, the reactivity of benzyl chloride is more than chlorobenzene. Therefore, the reactivity order of these compounds is,
Ethyl chloride > Benzyl chloride > Chlorobenzene
 Hence, option B is right.

Note: The nature of ethyl chloride can be burned, that is, flammable due to which it is advised to not use when an open flame is present. It is present in the gaseous state. Ethyl chloride undergoes both elimination and substitution reactions in presence of KOH.