Question

Identify the most stable carbocation among primary, secondary, and tertiary.

• A. Primary carbocation
• B. Secondary carbocation
• C. Tertiary carbocation
• D. All are equally stable

Hint:

Carbocation stability increases with alkyl substitution: \(3^\circ > 2^\circ > 1^\circ > CH_3^+\).

Answer 1

The Correct Option is C

Step 1: Understanding the Question:
This question evaluates the knowledge of electronic effects (inductive and hyperconjugation) on the stability of organic intermediates.
Step 2: Detailed Explanation:
Carbocations are electron-deficient species (6 electrons in valence shell).
Alkyl groups are electron-donating groups due to the \(+I\) (inductive) effect.
Furthermore, alkyl groups provide stabilization through hyperconjugation (delocalization of \(\sigma\)-electrons of C-H bonds into the empty p-orbital of the carbocation).
- Tertiary (\(3^\circ\)) carbocation: Has 3 alkyl groups donating electrons and several C-H bonds for hyperconjugation.
- Secondary (\(2^\circ\)) carbocation: Has 2 alkyl groups.
- Primary (\(1^\circ\)) carbocation: Has only 1 alkyl group.
Higher substitution leads to better dispersal of the positive charge.
Step 3: Final Answer:
The tertiary carbocation is the most stable among the three.