The Question is from neet-chemistry organic-chemistry-basics reaction-intermediates, and it was created by the author Mr. S M HUSSAIN

Question

Which of the following statements is INCORRECT regarding the stability of carbocations?

Mr. S M HUSSAIN · Accepted Answer

## CORE INFORMATION
✓ **Answer**: D
## CONCEPT FRAMEWORK
	**Primary Concept**: Carbocation Stability
	**Related Topics**: Inductive Effect, Resonance, Hyperconjugation
	**Prerequisites**: Understanding of carbocations, electron donating and withdrawing groups.
## SOLUTION PATHWAY
**Given Information**:
	Four statements regarding carbocation stability.
**Method & Steps**:
	1. Analyze each statement based on the factors affecting carbocation stability.
	Reasoning: Carbocation stability is influenced by neighboring electron donating groups and resonance.
	2. Identify the incorrect statement.
	Working: Electron-withdrawing groups destabilize carbocations.
	Key Point: More substituted carbocations are generally more stable.
	3. Select the option corresponding to the incorrect statement.
	Result: Option D
	Verification: Electron-withdrawing groups pull electron density away from the positively charged carbon, making it less stable.
## OPTION ANALYSIS
[A] ✓: Tertiary carbocations are more stable than secondary carbocations. This is correct because tertiary carbocations have three alkyl groups attached to the positively charged carbon, which donate electron density through the inductive effect, stabilizing the positive charge. More alkyl groups mean more inductive effect and greater stability.
[B] ✓: Resonance delocalizes the positive charge and increases carbocation stability.  This is correct.  Resonance structures distribute the positive charge over multiple atoms, thus reducing the charge density on any single atom and increasing stability.
[C] ✓: Hyperconjugation contributes to the stability of carbocations. This is correct. Hyperconjugation involves the interaction of the electrons in a C-H sigma bond adjacent to the carbocation with the empty p-orbital of the carbocation. This delocalizes the positive charge and increases stability.
[D] :x: Electron-withdrawing groups directly attached to the carbocation center increase its stability. This statement is INCORRECT.  Electron-withdrawing groups pull electron density away from the positively charged carbon, making it even more electron deficient and thus less stable. 
## LEARNING AIDS
	**Common Mistakes**:
		1. Confusing inductive and resonance effects: Remember that inductive effects are through sigma bonds, while resonance involves pi bonds and delocalized electrons.
		2. Ignoring the impact of hyperconjugation: While less significant than resonance or inductive effects from alkyl groups, hyperconjugation still contributes to carbocation stability.
	**Quick Tips**:
		1. More substituted carbocations are generally more stable: $3^\circ > 2^\circ > 1^\circ > methyl$
		2. Electron-donating groups stabilize carbocations, while electron-withdrawing groups destabilize them.

Mr. S M HUSSAIN · Answer

Tertiary carbocations are more stable than secondary carbocations.

Mr. S M HUSSAIN · Answer

Resonance delocalizes the positive charge and increases carbocation stability.

Mr. S M HUSSAIN · Answer

Hyperconjugation contributes to the stability of carbocations.

Mr. S M HUSSAIN · Answer

The correct Option is "Electron-withdrawing groups directly attached to the carbocation center increase its stability."

NEET Chemistry Organic Chemistry: Some basic principles and techniques Reaction Intermediates MCQs

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