The correct IUPAC name of the compound CH2 = CH – CH2OH is

The correct answer is Option (1) → Prop-2-en-1-ol

To name an unsaturated alcohol by the IUPAC system:

• Choose the longest chain that contains both the carbon bearing –OH and the C=C bond.

• Number it so that the principal functional group (–OH) gets the lowest locant; the double bond comes second.

• Name it as alk-x-en-y-ol: “e” of the alkene is dropped before a vowel.

For \( \ce{CH2=CH-CH2OH} \), the chain has 3 carbons. Numbering from the –\( \ce{CH2OH} \) end:

    ³CH₂=²CH–¹CH₂OH

–OH is on C-1 and the double bond starts at C-2, so the name is prop-2-en-1-ol.

Why the other options are incorrect

• Option (2) Allyl alcohol — Incorrect. This is the common name of the same compound, not its IUPAC name.

• Option (3) Vinyl alcohol — Incorrect. This is a different compound, \( \ce{CH2=CH-OH} \) (ethenol), with –OH directly on the double-bond carbon.

• Option (4) Prop-1-en-3-ol — Incorrect. Numbering from the other end gives –OH the higher locant (3); the principal group must get the lowest number.