The order of decreasing reactivity towards an electrophilic reagent, for the following would be: (i) benzene…
The order of decreasing reactivity towards an electrophilic reagent, for the following would be:
(i) benzene
(ii) toluene
(iii) chlorobenzene
(iv) phenol
(ii) $ > $ (iv) $ > $ (i) $ > $ (iii)
(iv) $ > $ (iii) $ > $ (ii) $ > $ (i)
(iv) $ > $ (ii) $ > $ (i) $ > $ (iii)
(i) $ > $ (ii) $ > $ (iii) $ > $ (iv)
Solution
Electrophiles have high affinity for electrons. They attack at the site where electron-density is highest. Electron withdrawing substances increases the electron density. The electron withdrawing tendency decreases in the order :
$-\mathrm{OH} > -\mathrm{CH}_3 > -\mathrm{H} > -\mathrm{Cl}$
Therefore, the correct order of reactivity towards electrophile is
$\mathrm{C}_6 \mathrm{H}_5 \mathrm{OH} > \mathrm{C}_6 \mathrm{H}_5 \mathrm{CH}_3 > \mathrm{C}_6 \mathrm{H}_6 > \mathrm{C}_6 \mathrm{H}_5 \mathrm{Cl}$
Related Theory
Electrophilic substitution reaction in haloarenes occur slowly because halogen has a negative inductive effect, it decreases the electron density on the benzene ring due to resonance.