# Effect on acidity of benzene due to electron withdrawing groups

With respect to the compounds IV, choose the correct statement(s).

1. Compound II becomes more acidic when it has a $$\ce{-NO2}$$ substituent.
2. The acidity of compounds follows the order I > IV > V > II > III.
3. The conjugate base of compound IV is aromatic.
4. The acidity of compound I is due to delocalization in the conjugate base.

I am not able to decide about the first statement properly. I compared the acidity by considering the conjugate base, which is the same (benzyne) even if $$\ce{NO2}$$ group is added.

However, the solution says that it will increase acidity because of being an electron withdrawing group.

• Do you really think conjugate base of II is benzyne? – Aniruddha Deb Sep 29 '20 at 16:48

Both the predictions are good. The $$\ce{NO2}$$ will actually be an effective electron withdrawing group, and the lost of that $$\ce{H}$$ will stabilize the compound (if there is and $$\ce{NO2}$$ on it). It is also important to rescue, that both effects will be stronger just on para or ortho position. You can make the different structures to check it.
• @Buttonwood The deprotonated form holds the extra electron (i.e. the negative charge) in an $\ce{sp^3}$ orbital which is parallel to the plane, whereas the pi system is perpendicular to the plane. So they can't interact with each other and conjugation is not a factor here. Simple inductive effect would predict ortho > meta >para in order of high to low stabilization of the anion. – S R Maiti Mar 28 at 20:20