Question

In the electrophillic substitution reactions of benzoic acid, which of the following statements best describes the expected reactivity pattern?

A) The m-positions are most activated to attack by the electrophile.

B) The o,p-positions are most activated to attack by the electrophile.

C) The o,p-positions are most deactivated to attack by the electrophile.

D) The m-positions are most deactivated to attack by the electrophile.

E) All positions (o, m, and p) are equally activated to attack by the electrophile

Answer 1

Option C is correct

The o,p-positions are most deactivated to attack by the electrophile.

  

When the attack take place at o,p-position then it contribute the str. I & II which are highly unstable. Due the presence of postive charge on the carbon atom bearing electron withdrawing COOH group in str. I & II the system beacome highly unstable. this type of structure is not possible when attack take place at m-position.

As the system attain highly unstability when attack take place at o,p-position these positions are most deactivated to attack by the electrophile.

It is clearly seems that COOH Group withdraw the electron density at o,p-position and make these positions deactivated to attack by electrophile.