JEE Main · 2021 · 27 Aug 2021 · Shift 2 · Haloalkanes and Haloarenes

The major product (A) formed in the reaction given below is

(A)(see structure)
(B)(see structure)
(C)(see structure)
(D)(see structure)
✓ Correct

Answer: (D)

Solution

Methoxide ion is a strong base, and although the substrate is a primary bromide, abstraction of a

β

-hydrogen from the benzylic carbon produces an alkene whose double bond is conjugated with the aromatic ring. This conjugation stabilises both the transition state and the product, so bimolecular elimination outruns substitution. Loss of

HBr

from

C_{6} H_{5} CH (C_{2} H_{5}) C H_{2} Br

therefore gives the styrene-type alkene

2

-phenylbut-

1

-ene,

C_{6} H_{5} C (= C H_{2}) C H_{2} C H_{3}

, as the major product.

JEE Main · 2021 · 27 Aug 2021 · Shift 2 · Single correct option

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