MHTCET 22 Apr 2025 Shift 2 Paper

Concept:An allylic halide has the halogen atom bonded to an $\mathrm{sp}^{3}$ carbon that is directly attached to a carbon-carbon double bond.Explanation:Check each option for the position of $\mathrm{X}$ relative to the double bond.Option A: $\mathrm{CH}_{2}=\mathrm{CH}-\mathrm{CH}_{2}-\mathrm{X}$ — $\mathrm{X}$ is on the carbon next to $\mathrm{C}=\mathrm{C}$. Allylic.Option B: $\mathrm{CH}_{3}-\mathrm{CH}=\mathrm{CH}-\mathrm{CH}_{2}-\mathrm{X}$ — $\mathrm{X}$ is on the carbon adjacent to $\mathrm{C}=\mathrm{C}$. Allylic.Option C: $\mathrm{CH}_{3}-\mathrm{CH}_{2}-\mathrm{CH}=\mathrm{CH}-\mathrm{CH}_{2}-\mathrm{X}$ — $\mathrm{X}$ is on the carbon directly attached to $\mathrm{C}=\mathrm{C}$. Allylic.Option D: $\mathrm{CH}_{3}-\mathrm{CH}=\mathrm{CH}-\mathrm{CH}_{2}-\mathrm{CH}_{2}-\mathrm{X}$ — here $\mathrm{X}$ is separated from the double bond by one extra $\mathrm{CH}_{2}$ group.Thus, the halogen is not on the carbon adjacent to the double bond, so this is not an allylic halide.Answer:$\mathrm{D} \quad \mathrm{CH}_{3}-\mathrm{CH}=\mathrm{CH}-\mathrm{CH}_{2}-\mathrm{CH}_{2}-\mathrm{X}$