Consider all the structural isomers with molecular formula C _ 5 H _ 11 Br are separately treated with KOH ( aq ) to give respective substitution products, without any rearrangement. The number of products which can exhibit optical isomerism from these is \_\_\_\_.
A. A
For C₅H₁₁Br structural isomers to show optical isomerism after KOH substitution (Br→OH), the resulting product must have a chiral center (asymmetric carbon with four different groups). Possible carbon skeletons: n-pentane, 2-methylbutane, 2,2-dimethylpropane. Analysis of isomers: 2-bromopentane → CH₃CHOHCH₂CH₂CH₃: C2 bonded to H, OH, CH₃, and CH₂CH₂CH₃ (chiral). 3-bromopentane → CH₃CH₂CHOHCH₂CH₃: C3 bonded to H, OH, CH₂CH₃, CH₂CH₃ (NOT chiral). 3-bromo-2-methylbutane → CH₃CH(CH₃)CHOHCH₃: Chiral center present. 1-bromo-3-methylbutane → HOCH₂CH(CH₃)CH₂CH₃: C2 bonded to H, OH, CH₃, and CH₂CH₃ (chiral). 2,2-dimethylpropane derivatives: No chiral centers possible. Compounds giving chiral products: 2-bromopentane, 3-bromo-2-methylbutane, and 1-bromo-3-methylbutane. Total = 3.
Related: Chemistry — Haloalkanes and Haloarenes · All PYQ Banks