Key Idea : Deactivating groups attached on benzene ring are meta-directing groups.
The product formed in the given reaction is
In the above reaction, '
N′ bears a positive charge that decreases the electron density due to its strong
− I effect and hence is called a deactivating group. The overall electron density on the benzene ring decreases (inspite of three
−CH3 groups) thus, the electrophilic substitution becomes difficult. The electron density on 0 -and
p -position is comparatively lesser than that at
m -position. So, electrophile attacks at
m -position i.e. substitution occur at
m -position.