The number of stereoisomers obtained by bromination of trans-2-butene is
- (A)1✓ Correct
- (B)2
- (C)3
- (D)4
Answer: (A)
Solution
Trans-2-butene undergoes anti-addition of bromine. The bromonium ion intermediate is attacked by bromide from the opposite face, leading to anti-stereochemistry. Starting from trans-2-butene (CH₃-CH=CH-CH₃), bromination gives two enantiomeric products: (2R,3R)-2,3-dibromobutane and (2S,3S)-2,3-dibromobutane. These are non-superimposable mirror images, so there are 2 stereoisomers.
JEE Advanced · 2007 · 08 Apr 2007 · Paper 2 · Single correct option