In the electrophilic substituion of benzene ring, the second substituent is directed by the group already present. Electron releasing groups (+I and +M) are ortho-para-directing and activating, whreas the electron withdrawing groups (-I and -M) are meta-directing and deactivating.
Halogens are placed under the category of +T (Tautomeric) groups because they have -Ibdyctuve abd +Mesomeric effect. These groups are deactivating but ortho-para-directing.
In the introduction of third group to the benzene ring, the product of minimum steric gindrance is formed.
A deactivating group in electrophilic substitution reaction :
A. deactivates only rotho- and para-positions
B. deactivates only meta-position
C. deactivates meta-position more than ortho-and para-positions.
D. deactivatesn ortho- and para-positions more than meta-position