Question

Why methyl
group is ortho para directing group?

Answer 1

Answer:

Methyl group (CH3) is Sp3 hybridised, while the carbon in a benzene ring is Sp2. We know, that electronegativity decreases in the following order -:

Sp, Sp2, Sp3...

(Since, E.N is inversely proportional to S-character)

So, Sp3 is less e.n than Sp2. Hence, when the double bond next to Ch3 breaks, the elctron pair shifts away from CH3 (less e.n) towards the C of the benzene ring. This makes the ortho-para positions gain slight negative charge. Now, when an elctrophile comes in its vicinity, it attacks the ortho para positions. Therefore, the methyl group is the ortho para directing group.