Question

The correct stability order of the following diazonium salts is:

Choose the correct answer from the options given below: 
 

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

Hint:

Electron donating groups increase diazonium stability, while strong electron withdrawing groups decrease it.

Answer 1

The Correct Option is A

To determine the correct stability order of the given diazonium salts, we need to consider the effect of substituents on the benzene ring. The stability of an aryl diazonium salt is influenced by the nature of substituents attached to the aromatic ring. 

1. Electron-donating groups (EDGs): These groups, such as -OCH₃, increase the stability of the diazonium ion through resonance stabilization by donating electron density to the ring.
2. Electron-withdrawing groups (EWGs): Groups like -NO₂ and -CN decrease the stability of the diazonium ion by withdrawing electron density from the ring. This destabilization is due to a decrease in resonance and reduced positive charge delocalization.

Let's analyze the given structures:

• Structure (A): Contains a -OCH₃ group, which is an EDG. This group will increase the stability of the diazonium salt due to resonance donation.
• Structure (B): Contains a -NO₂ group, which is an EWG. This group will decrease the stability due to electron withdrawal.
• Structure (C): Has no additional substituent, making it less stable than those with EDGs but more stable than those with strong EWGs.
• Structure (D): Contains a -CN group, another strong EWG, which similarly decreases stability.

Considering these effects, the stability order is determined as follows:

• A > C > D > B, where (A) is the most stable due to the presence of the electron-donating -OCH₃ group, and (B) is the least stable due to the strong electron-withdrawing -NO₂ group.

Therefore, the correct answer is: A $>$ C $>$ D $>$ B.