Which of the following is the most effective way to stabilize a $\mathrm{carbocation}$?

• A. Attaching electron-withdrawing groups directly to the $\mathrm{carbocation}$ center
• B. Increasing the number of alkyl groups attached to the positively charged carbon ($\mathrm{hyperconjugation}$)
• C. Decreasing the resonance delocalization of the positive charge
• D. Placing the $\mathrm{carbocation}$ on a primary carbon rather than a tertiary carbon

Answer: (B)

Verified step by step guidance

1. Understand that a carbocation is a positively charged carbon atom, which is electron-deficient and thus highly reactive and unstable.
2. Recall that carbocation stability is influenced by the ability to delocalize or distribute the positive charge, reducing its electron deficiency.
3. Recognize that electron-withdrawing groups attached directly to the carbocation center actually destabilize it by pulling electron density away, increasing the positive charge density.
4. Know that resonance delocalization stabilizes carbocations by spreading out the positive charge over multiple atoms, so decreasing resonance would reduce stability.
5. Focus on hyperconjugation: increasing the number of alkyl groups attached to the carbocation allows adjacent C-H or C-C sigma bonds to overlap with the empty p orbital of the carbocation, donating electron density and stabilizing the positive charge effectively.