Account for the greater reactivity and the o, p-orientation in electrophilic substitution of biphenyl despite the electron-attracting inductive effect of the phenyl group.

Asked by Topperlearning User | 25th Jul, 2014, 07:18: AM

Expert Answer:

In attack at the o-,p- positions the unreacted ring can stabilize the + charge on the attached C of the σ complex by electron-releasing delocalization that results in delocalizing the + charge to both rings. Such delocalization is impossible with the intermediate from meta substitution which does not have the + charge on the C bonded to the Ph substituent. The + charge cannot be incorporated into the second ring, and delocalization is confined to one ring.

Answered by  | 25th Jul, 2014, 09:18: AM