Question

Increasing order of acidic strength of given compounds is:

• A. $\left(ii\right)<\left(i\right)<\left(iv\right)<\left(iii\right)$
• B. $\left(i\right)<\left(iii\right)<\left(iv\right)<\left(ii\right)$
• C. $\left(i\right)<\left(iii\right)<\left(ii\right)<\left(iv\right)$
• D. $\left(iii\right)<\left(i\right)<\left(iv\right)<\left(ii\right)$

Answer 1

The correct option is D $\left(iii\right)<\left(i\right)<\left(iv\right)<\left(ii\right)$

More be the electron-withdrawing ability of the group, attached to the ring, more be its acidic strength.

Here $-CN$ is EWG but $-Cl,-Me,-OC{H}_3$ is EDG so they decrease acidity.

As $+M$ effect is stronger than $+I$ effect, so acidity decreases more for $-OC{H}_3$.

Hence, correct order is $\left(iii\right)<\left(i\right)<\left(iv\right)<\left(ii\right)$