JEE Main · 2021 · 31 Aug 2021 · Shift 1 · General Organic Chemistry

Choose the correct name for compound given below :

(A)(4E)-5-Bromo-hex-2-en-4-yne
(B)(2E)-2-Bromo-hex-4-yn-2-ene
(C)(2E)-2-Bromo-hex-2-en-4-yne✓ Correct
(D)(4E)-5-Bromo-hex-4-en-2-yne

Answer: (C)

Solution

The six-carbon chain carries both a double bond and a triple bond, and the chain is numbered to give the two unsaturations the lowest set of locants, the double bond taking the lower number when the set is otherwise tied. This fixes the double bond at C-2 and the triple bond at C-4, with bromine on C-2. The two higher-priority groups across the double bond lie on opposite sides, so the configuration is

E

. The compound is (2E)-2-bromohex-2-en-4-yne.

JEE Main · 2021 · 31 Aug 2021 · Shift 1 · Single correct option

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