Logo
Jeeify
MCQEasyJEE 2025Nomenclature (IUPAC & Common)

JEE Chemistry 2025 Question with Solution

The IUPAC name of the following compound is:

Structural formula of a seven-carbon chain with one double bond, one triple bond, and an OH group at the middle carbon, with numbering shown beneath the chain.
  • A

    4-Hydroxyhept-1-en-6-yne

  • B

    4-Hydroxyhept-6-en-1-yne

  • C

    Hept-6-en-1-yn-4-ol

  • D

    Hept-1-en-6-yn-4-ol

Answer

Correct answer:D

Step-by-step solution

Standard Method

Given: A seven-carbon organic compound with one double bond, one triple bond, and one hydroxyl group is shown.

Find: The correct IUPAC name.

From the given structure, the parent chain contains 77 carbon atoms, so the parent word is hept.

The displayed chain is:

CH2=CH−CH2−CH(OH)−CH2−C≡CH\text{CH}_2=\text{CH}-\text{CH}_2-\text{CH}(\text{OH})-\text{CH}_2-\text{C}\equiv\text{CH}

Number the chain so that the multiple bond gets the lowest possible locant. On numbering from the end nearer the double bond, the positions become:

  • double bond at 11
  • triple bond at 66
  • hydroxyl group at 44

Therefore, the name is written as:

Hept-1-en-6-yn-4-ol\text{Hept-1-en-6-yn-4-ol}

Hence, the correct option is D.

Option Elimination

Options using hydroxy as a prefix are not preferred here because the hydroxyl group is the principal functional group, so it should appear as the suffix ol.

Among the remaining names, compare the locants of the multiple bonds. IUPAC naming gives the lower locant to the double bond in the tie situation shown here, so en gets locant 11 and yn gets locant 66.

Thus Hept-6-en-1-yn-4-ol is incorrect, and the correct name is Hept-1-en-6-yn-4-ol.

Common mistakes

  • Treating OH as a prefix hydroxy instead of the suffix ol. This is wrong because the hydroxyl group is the principal functional group here. Use -ol in the final name.

  • Numbering the chain from the wrong end. This gives incorrect locants for the double and triple bonds. Always choose numbering that gives the multiple bond system the lowest possible locants according to IUPAC rules.

  • Writing Hept-6-en-1-yn-4-ol by prioritizing the triple bond numbering. This is incorrect here; between equivalent possibilities, the double bond should receive the lower locant.

Practice more Nomenclature (IUPAC & Common) questions

Get unlimited AI-adaptive practice, mastery tracking, and an AI tutor that explains every step — free to start.

Start free trialMore on Nomenclature (IUPAC & Common)

Related questions