NEETChemistryGeneral Organic Chemistry
Given below are two statements: one is labelled as Assertion (A) and the other is labelled as Reason (R). Assertion (A): Isopropyl carbocation is more stable than tert -butyl carbocation. Reason (R): tert -Butyl carbocation is stabilized by 9 hyperconjugative structures whereas isopropyl carbocation is stabilized by 6 hyperconjugative structures. In the light of the above statements, choose the most appropriate answe
Options
- ABoth (A) and (R) are correct and (R) is the correct explanation of (A)
- BBoth (A) and (R) are correct but (R) is not the correct explanation of (A)
- C(A) is correct but (R) is not correct
- D(A) is not correct but (R) is correct
Correct answer
D. (A) is not correct but (R) is correct
Step-by-step solution
Assertion (A) is incorrect because tert -butyl carbocation is a 3^ carbocation and is more stable than isopropyl carbocation, which is a 2^ carbocation. Reason (R) is correct. The stability of alkyl carbocations is governed by hyperconjugation. The tert -butyl carbocation, (CH₃)₃C^+ , has 9 -hydrogens, leading to 9 hyperconjugative structures. The isopropyl carbocation, (CH₃)₂CH^+ , has 6 -hydrogens, leading to 6 hyperconjugative structures. Greater the number of hyperconjugative structures, higher is the stability