ExamsMy practice
Ques. 1JEE Main 2024, 30 January (Evening Shift)
The correct stability order of carbocations is
- (CH3)3C > CH3- CH2 > (CH3)2 CH > CH3
- (CH3)3 C > (CH3)2 CH > CH3- CH2 > CH3
- CH3 > CH3- CH2 > CH3- CH3 | CH > (CH3)3C
- CH3 > (CH3)2 CH > CH3- CH2 > (CH3)3 C
Answer
(2) (CH3)3 C > (CH3)2 CH > CH3- CH2 > CH3
Solution
Stability of a carbocation ∝ number of α-H (hyperconjugation) and +I effect of alkyl groups
(CH3)3 C: 9 α-H ; (CH3)2 CH: 6 α-H
CH3- CH2: 3 α-H ; CH3: 0 α-H
∵ more α-H ⇒ more hyperconjugative structures ⇒ more dispersal of + charge
∴ 3° > 2° > 1° > methyl:
(CH3)3 C > (CH3)2 CH > CH3- CH2 > CH3
Answer: (2)