Question

How many stereoisomers does the molecules have? CH 3 CH = CHCH 2 CHBrCH 3 [AIPMT (Prelims)-2008] (1) 2 (2) 4 (3) 6 (4) 8

Answer 1

The molecule has 4 stereoisomers.

This can be obtained only if you first draw an open structure of the compound then from there you go as follows;

CH3CH=CHCH2C*BrCH3

So then in the first instance we can say that between the carbon atoms having the double bond, we have a geometric isomer.

The carbon which have (*) has optical isomer.

Thus in the above formula, we have only one chiral carbon. So there are 2 stereogenic center.

Then to find the number stereoisomers use the formula 2^n; 2^2 = 4 stereoisomers.