Alkenes and bromine

Addition of bromine

Bromine reacts with alkenes at room temperature, producing a di-substitued halogenoalkane. The reaction is used as a test for unsaturation.

Mechanism

Bromine is a non-polar molecule. When bromine approaches an alkene, the electrons in the   -bond repel the electrons in the Br-Br bond. THs induces a dipole in the Br  molecule, Br - Br. The Br molecule is now slightly polar.

• Th electron pair in the   -bond is attracted to the slightly positive bromine atom…