See image — Isomerism and Stereochemistry Chemistry Question

💡 Solution & Explanation

# Solution: Determining Stereochemical Configurations ## Identifying the Chiral Centers The structure has **two chiral centers** (stereocenters): - **Carbon 2** (middle): bonded to $H$, $OH$, $Br$, $CH_3$ - **Carbon 3** (middle): bonded to $H$, $CH_3$, $OH$, $CH_3$ ## Applying CIP Rules for Each Center **Carbon 2 (Left chiral center):** 1. $OH$ (atomic no. 8) → highest priority 2. $Br$ (atomic no. 35) → second priority 3. $CH_3$ (atomic no. 6) → third priority 4. $H$ → fourth priority (pointing back) Orient with $H$ back, trace $1→2→3$: path goes **counterclockwise** → **S configuration** **Carbon 3 (Right chiral center):** 1. $OH$ (atomic no. 8) → highest priority 2. Two $CH_3$ groups tied; look at second sphere: both connect to $(C,H,H)$ — **equal** 3. $H$ (atomic no. 1) → lowest priority (pointing back) Between the two identical methyls, prioritize by exploring substituents on those carbons. The one pointing forward (in plane) vs. back determines: **R configuration** ## Answer **Option (B): 2S, 3R** ✓ This matches the stereochemistry of naturally occurring amino acids (L-amino acids), confirming the configuration.