91Ó°ÊÓ

The geometrical isomers are also stereoisomers. They show cis-trans geometry. If two substituents have the same stereochemistry, cis isomers are formed and vice versa for trans isomers.

Optical isomers are also stereoisomers that have chiral centers but lack a plane of symmetry. If two compounds with the same molecular formula have opposite stereochemistry, they form stereoisomers.

a. The bromination of the alkene substrate allows the trans addition of bromine atoms on the sides of the double bond.

Stereoisomers obtained from a

b. The chlorination of the alkene substrate allows the trans addition of the chlorine atom and the hydroxide ion on the sides of the double bond.

Stereoisomers obtained from b

c. In the presence of DMSO and water, NBS allows trans addition on the double bond.

Stereoisomers obtained from c