JEE PYQ: Hydrocarbons Question 15
Question 15 - 2020 (02 Sep Shift 1)
The major product in the following reaction is:
$\text{H}_3\text{C}-\text{C}(=\text{CH}_2)(-\text{cyclopentyl}) \xrightarrow{\text{H}_3\text{O}^+/\text{Heat}}$
(1) 1,1-Dimethylcyclopentane
(2) 1-Methyl-1-isopropylcyclopentane (with two $\text{CH}_3$)
(3) 1,2-Dimethylcyclopentane (with $\text{CH}_3$ groups)
(4) 1-Methyl-2-isopropylcyclopentanol
Show Answer
Answer: (2)
Solution
$\text{H}_3\text{O}^+$ protonates the exocyclic double bond. The resulting carbocation undergoes rearrangement (ring expansion/methyl shift) to give the more stable product: 1,1-dimethylcyclopentane derivative.
BETA
