See image — Isomerism and Stereochemistry Chemistry Question

💡 Solution & Explanation

# Most Stable Conformation of 3-Fluorobutan-2-ol **Structure:** $CH_3-CHOH-CHF-CH_3$ **Step 1: Identify the relevant dihedral angle** The stability depends on the dihedral angle between the $-OH$ group (at C2) and the $-F$ atom (at C3). We need to evaluate rotations around the C2–C3 bond. **Step 2: Analyze steric and electronic effects** - **Gauche interaction:** When $OH$ and $F$ are gauche (60°), they experience repulsion (~3-4 kcal/mol for typical gauche strain) - **Anti conformation:** When $OH$ and $F$ are anti (180°), groups are maximally separated → minimal repulsion **Step 3: Consider electronegativity** Both $OH$ and $F$ are highly electronegative. In the **anti form**, they point in opposite directions, minimizing dipole–dipole repulsion and electronic destabilization. **Step 4: Compare all options** - Fully eclipsed: Maximum steric clash ✗ - Partially eclipsed: Still significant steric strain ✗ - Gauche: Both bulky/polar groups at 60° causes repulsion ✗ - **Anti: Maximum separation of $OH$ and $F$ groups** ✓ **Answer: (D) Anti form** The anti conformation maximizes the distance between the bulky and polar $-OH$ and $-F$ substituents, providing the lowest energy state.