Consider all the structural isomers with molecular formula C_5H_11 Br are separately treated with KOH ( aq ) to give respective substitution products, without any rearrangement. The number of product…

Question

Consider all the structural isomers with molecular formula C_5H_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 \_ \_ \_ \_ .

Accepted Answer

Correct answer: 3. (3) For C_5H_11 Br 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 CH_3 CHOHCH_2 CH_2 CH_3 : C2 bonded to H , OH , CH_3, and CH_2 CH_2 CH_3 (chiral). 3-bromopentane CH_3 CH_2 CHOHCH_2 CH_3 : C_3 bonded to H , OH , CH_2 CH_3 , CH_2 CH_3 ( NOT chiral). 3-bromo-2-methylbutane CH_3 CH ( CH_3 ) CHOHCH_3 : Chiral center present. 1-bromo-3-methylbutane HOCH_2 CH ( CH_3 ) CH_2 CH_3 : C2 bonded to H , OH , CH_3, and CH_2 CH_3 (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.

$Consider all the structural isomers with molecular formula C_{5} H_{11} Br are separately treated with KOH (aq) to give respective substitution products, without any rearrangement. The number of products which can exhibit optical isomerism from these is____.$

Solution

More Haloalkanes & Haloarenes PYQs