Question

How many chiral stereoisomers can be drawn for $2$-bromo-$3$-chlorobutane?

• A. 2
• B. 3
• C. 4
• D. 5

Answer 1

Answer: (C)

The structure of $2$-bromo-$3$-chlorobutane is
$C{H}_3-\underset{\stackrel{|}{\mathrm{Br}}}{\stackrel{\ast }{C}}H-\underset{\stackrel{|}{\mathrm{Cl}}}{\stackrel{\ast }{C}}H-C{H}_3(C^{\ast }=$ asymmetric carbon atom) The number of chiral stereoisomers $=2^n$
(where, $n$ = number of asymmetric carbon atoms) $=2^2=4$ The structure of these isomers are as