Question

Which of the following is more reactive towards nitration?

• A.
• B.
• C.
• D.

Answer 1

The correct option is D

Rate of electrophilic substitution reaction is proportional to the stability of the carbocation intermediate (Arenium ion) formed in the reaction.

$\text{Stability of Arenium ion}\propto \text{+R, +H, +I groups}$

$\text{Stability of Arenium ion}\propto \frac{1}{\text{-R, -H, -I groups}}$
Increase in number of $+H$ group in the compound will increase the number of hyperconjugative structures and it also has resonance stablization
In (d), the formed carbocation is more stabilised by $3$ methyl groups.

In (c), the formed carbocation is less stabilised than (d) because it has only two methyl groups.

In (b), the formed carbocation is less stabilised than (c) because it has only one methyl group.

In (a) i.e benzene is neither stabilised nor destabilised.

Thus, compound (d), is more reactive towards nitration.