MHTCET 16 May 2024 Shift 2 Paper

Concept:An allylic alcohol has the $-\mathrm{OH}$ group attached to a saturated $sp^3$ carbon that is directly adjacent to a carbon-carbon double bond.Explanation:For each option, check the position of the $-\mathrm{OH}$ group relative to the $C{=}C$ bond.In but-1-en-1-ol, the $-\mathrm{OH}$ group is attached directly to a doubly bonded carbon, so it is a vinylic alcohol, not allylic.In but-3-en-1-ol, the carbon bearing $-\mathrm{OH}$ is separated from the double bond by one saturated carbon, so it is not allylic.In but-2-en-1-ol, the structure is $\mathrm{HOCH_2{-}CH{=}CH{-}CH_3}$.Here, the carbon carrying $-\mathrm{OH}$ is saturated and directly adjacent to the $C{=}C$ bond.Hence, but-1-en-1-ol satisfies the condition for an allylic alcohol.Butane-1,3-diol contains no double bond and cannot be allylic.Answer:But-2-en-1-ol (Option C).