question_answer 92)

  Nitration is an example of aromatic electrophilic substitution and its rate depends upon the group already present in the benzene ring. Out of benzene and phenol, which one is more easily nitrated and why ?

Answer:

                  Nitration of benzene and phenol is an electrophilic substitution reaction. The rate of any electrophilic substitution reaction depends upon the electron density in the aromatic ring. Obviously, higher the electron density in the aromatic ring, higher is the rate of electrophilic substitution reaction. Now the presence of OH group in phenol, increases the electron density at ortho and para position by +R effect. Since the electron density is more in phenol than in benzene, therefore, phenol is more easily nitrated than benzene.