JEE Main 2017 · 9 Apr · Shift 1 · Chemistry Q54

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ChemistrySingle correct+4 / -1Question 54 of 90

The major product of the following reaction is :

3-Methylcyclohexene treated with Br₂/hν.

3-Bromo-6-methylcyclohexene

Cyclohexene ring with CH₃ on the allylic carbon on one side of the double bond and Br on the allylic carbon on the other side.

3-Bromo-3-methylcyclohexene

Cyclohexene ring with CH₃ and Br on the same allylic carbon.

3-(Bromomethyl)cyclohexene

Cyclohexene ring with a CH₂Br group on the allylic carbon.

1,2-Dibromo-3-methylcyclohexane

Cyclohexane ring with CH₃ and, on the next two carbons, Br and Br.

Answer and worked solution

Official answer: B

Br₂/hν brominates the allylic position by a radical route. The tertiary allylic C-H (on the carbon bearing CH₃) gives the most stable radical, so the product is 3-bromo-3-methylcyclohexene, structure (2).

Topics:Alkenes Reactive intermediates

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JEE Main 2017 · 9 Apr · Shift 1, Chemistry question 54