Question

Arrange the following compounds A, B, C, and D in decreasing order of acidic strength:


Choose the correct answer from the options given below:

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

Hint:

Electron-withdrawing groups like NO2 and SO3H increase acidity, while electrondonating groups such as OCH3 and CH3 reduce acidity.

Answer 1

The Correct Option is B

The acidic strength of these compounds can be determined based on the substituents attached to the aromatic ring, which influence the electron density and hence the acidity.

• Compound A: Has two \( NO_2 \) groups, which are electron-withdrawing groups that increase the acidity.
• Compound B: Has a \( SO_3H \) group, which is an extremely strong electron-withdrawing group, significantly increasing the acidity, but still lower than the combination of two \( NO_2 \) groups in A.
• Compound C: Has an \( OCH_3 \) group, which is electron-donating and thus lowers the acidity.
• Compound D: Has a \( CH_3 \) group, another electron-donating group, further reducing the acidity.

Thus, the correct order of acidity is \( A > C > D > B \), where compound A is the most acidic, followed by C, D, and B.