Question

Choose the correct order of acidic strength for the following compounds:

• A. A > B > C
• B. C > B > A
• C. B > C > A
• D. A > C > B

Answer 1

The correct option is B C > B > A

Acidic strength depends on the stability of conjugate base formed :


In A and B, $-N{H}_2$ and $-OC{H}_3$ both show $+M$ effect, and hence destabilizes the conjugate base formed. $+M$ strength of $-N{H}_2$ is more than that of $-OC{H}_3$, so conjugate base A is less stable than conjugate base of B.
So, B is more acidic than A.
In C :
$-C{F}_3$ shows $-I$ effect , and hence stabilizes the conjugate base.
So, C is the most acidic compound.
Correct order is
C > B > A