Question

Which one of the following statements is correct?

• A. The order of stability of Carbonions is C\(_6\)H\(_5\)CH\(_2\)\(^-\)<(C\(_6\)H\(_5\))\(_2\)CH\(^-\)<(C\(_6\)H\(_5\))\(_3\)C\(^-\)
• B. In CH\(_3\)\(^+\), Carbon carrying positive charge is sp\(^3\) hybridise(D)
• C. In CH\(_3\)\(^-\), Carbon carrying negative charge is sp\(^2\) hybridise(D)
• D. The order of stability of Carbocations is (C\(_6\)H\(_5\))\(_3\)C\(^+\)<(C\(_6\)H\(_5\))\(_2\)CH\(^+\)<C\(_6\)H\(_5\)CH\(_2\)\(^+\)

Hint:

For carbonions and carbocations, always consider the effects of resonance and hybridization. For carbocations, more substituted carbocations are more stable due to hyperconjugation and resonance stabilization.

Answer 1

The Correct Option is A

The stability of carbonions (negatively charged species) depends on the electron donation or withdrawal effect of substituents and the hybridization of the carbon carrying the charge. Here’s the reasoning for the options: - Option A: The order of stability of carbonions is influenced by inductive and resonance effects. In this case, the order is correct because the phenyl group (C\(_6\)H\(_5\)) can stabilize the negative charge through resonance. The more phenyl groups attached to the carbon, the greater the resonance stabilization, leading to greater stability. Thus, the order of stability is: \[ \text{C}_6\text{H}_5\text{CH}_2^-<(\text{C}_6\text{H}_5)_2\text{CH}^-<(\text{C}_6\text{H}_5)_3\text{C}^- \] - Option B: In CH\(_3\)\(^+\), the carbon carrying the positive charge is sp\(^2\) hybridised, not sp\(^3\). This is because CH\(_3\)\(^+\) is a methyl cation, and the sp\(^2\) hybridization allows for the maximum overlap of orbitals in the planar structure. - Option C: In CH\(_3\)\(^-\), the carbon carrying the negative charge is sp\(^3\) hybridise(D) The negative charge is localized on the carbon atom, and sp\(^3\) hybridization minimizes electron-electron repulsion. - Option D: This option presents an incorrect order for the stability of carbocations. The correct order of stability for carbocations is: \[ (\text{C}_6\text{H}_5)_3\text{C}^+>(\text{C}_6\text{H}_5)_2\text{CH}^+>\text{C}_6\text{H}_5\text{CH}_2^+ \] This order is based on the inductive and resonance effects from the phenyl groups, where the more substituted carbocation is more stabilized due to increased electron donation.