Question

Choose the correct statment(s) for the following compounds :

• A. $I$ is more acidic than $II$
• B. $I$ is less acidic than $II$
• C. $III$ is less acidic than $IV$
• D. $III$ is more acidic than $IV$

Answer 1

Answer: (A), (C)

$III$ is less acidic than $IV$

For I and II :
Ortho effect :
In general, whenever a group is present at the ortho position of benzoic acid, irrespective of its nature (EDG or EWG), it increases the acidic strength as compared to benzoic acid itself.
So, I is more acidic than II

$\text{Stability of conjugate base}\propto \text{Acidic strength}$
For III and IV:



$-C{H}_3$ group at meta position shows $+I$ effect and thus destabilizes the negative charge by increasing the electron density. Thus, the stability of conjugate base formed by structure III is less as compared to conjugate base formed by IV.
So, III is less acidic than IV.