Arrange the following set of compounds in the order of their decreasing relative reactivity with an electrophile. Give reason.
The methoxy group (-OCH3) is electron realising group. It increases the electron density in benzene nucleus due to resonance effect (+R-effect). Hence, it makes anisole more reactive than benzene towards electrophile.
In case of alkyl halides, halogens are moderately deactivating because of their strong - I effect. Thus, overall electron density in benzene ring decreases. It makes further substitution effect.
-NO2 group is electron withdrawing group. It decreases the electron density in benzene nucleus due to its strong - R - effect and strong - I - effect. Hence, it makes nitrobenzene less reactive. Therefore, overall reactivity of these three compounds towards electrophiles decreases in the following order