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Organic Chemistry · Question of the Day

Organic Chemistry Question of the Day

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Monday, September 21, 2026

What is the correct IUPAC name for the compound with the structure: CH3CH2CH=CHCH(Br)CH2CH3CH_3CH_2CH=CHCH(Br)CH_2CH_3?

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Question of the Day

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What is the correct IUPAC name for the compound with the structure: CH3CH2CH=CHCH(Br)CH2CH3CH_3CH_2CH=CHCH(Br)CH_2CH_3?

  1. 4-bromohept-2-ene (correct answer)
  2. 4-bromohept-3-ene
  3. 4-bromo-2-heptene
  4. 3-bromohept-4-ene

Explanation: The correct IUPAC name is 4-bromohept-2-ene. The longest carbon chain has 7 carbons (hept-). The alkene takes priority over the halide, so we number to give the alkene the lowest possible number. Numbering from the left gives the alkene at position 2-3, while numbering from the right would give position 4-5. Therefore, we number from the left: the alkene is at position 2 (hept-2-ene) and the bromine is at position 4. Choice B incorrectly identifies the alkene position. Choice C uses outdated nomenclature. Choice D numbers from the wrong direction.