See image — Isomerism and Stereochemistry Chemistry Question

💡 Solution & Explanation

# Optical Isomers in 2,3-dichlorobutane **Step 1: Draw the structure of 2,3-dichlorobutane** $$CH_3-CHCl-CHCl-CH_3$$ Chlorine atoms are attached to carbons 2 and 3. **Step 2: Identify chiral centers** - Carbon 2: bonded to $Cl$, $H$, $CH_3$, and $CHClCH_3$ → **chiral** - Carbon 3: bonded to $Cl$, $H$, $CH_3$, and $CHClCH_3$ → **chiral** Both C2 and C3 are stereocenters with different groups attached. **Step 3: Determine stereoisomers** With 2 chiral centers, maximum possible stereoisomers = $2^2 = 4$ However, check for **meso compounds** (internal plane of symmetry): The (2R, 3S) and (2S, 3R) configurations produce the same compound due to a plane of symmetry through the molecule. **Step 4: Count optically active isomers** - **(2R, 3R)** — optically active - **(2S, 3S)** — optically active - **(2R, 3S) = (2S, 3R)** — meso compound (optically inactive) **Result: 2 optically active isomers** **Answer: (B) 2**