Arrange the following in increasing order of reactivity towards sulphonation with fuming sulphuric acid:

benzene, toluene, methoxybenzene, chlorobenze. (Explain the reason.)

Cholrobenzene< benzene< toluene< methoxybenzene

​Cholorobenzene is deactivating the ring towards sulphonation as compared to benzene as halogens are electron withdrawing group and they pull the electron density of benzene ring hence destabilizes the intermediate.

Toluene activates the ring towards sulphonation as compared to benzene because it carry a alkyl group which is electron donation in nature hence stabilizes the intermediate and favours the reaction.

Methoxy group on benzene activates the ring by donation of electron pairs through resonance. It strongly favors the sulphonation on O and p position of the ring.

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