g n the following three compounds(1,2,3) arrange their relative reactivity towards the reagent CH3Cl / AlCl3. Justify your order

3 > 2> 1

Explanation:

Aromatic compounds undergo electrophilic substitution reaction which passes through a positively charged intermediate to yield the product.

Substituted benzenes may be more or less reactive towards electrophilic aromatic substitution than benzene molecule depending on the nature of the substituent.

Certain substituents increase the ease of reaction of benzene towards aromatic substitution.

If we look at the compounds closely, we will notice that toluene reacts readily with CH3Cl / AlCl3. This is because, the methyl group is electron donating hence it stabilizes the positively charged intermediate produced in the reaction.

Carbonyl compounds are electron withdrawing substituents hence they decrease the magnitude of the positive charge and hence decrease the rate of electrophilic aromatic substitution.