Question

Explain the fact that in aryl alkyl ethers 

(i) The alkoxy group activates the benzene ring towards electrophilic substitution reaction. 

(ii) It directs the incoming substituent to ortho and para position in benzene ring.

Answer 1

(i) The electron charge density is increased on benzene ring due to transfer of one lone pair of electron from oxygen to benzene ring. Thus benzene ring is activated by alkoxy group. 

(ii) The negative charge is developed either on ortho or para position. Therefore electrophile can attack only at these positions. Due to this reason in aryl alkyl ethers incoming substituents is directed towards ortho and para positions.