Electrophilic addition of bromine

Question 1

Bromine (Br2) is a non-polar molecule as both atoms have similar electronegativities and therefore share equally the electrons in the covalent bond

However, when a bromine molecule gets closer to the double bond of an alkene, the high electron density in the double bond repels the electron pair in Br-Br away from the closest Br atom

which leads to

Answer 1

As a result of this, the closest Br atom to the double bond is slightly positive and the further Br atom is slightly negatively charged

Question 2

In an addition reaction, the closest Br atom acts as an electrophile and

The Br-Br bond ……… forming

Answer 2

accepts a pair of electrons from the C-C bond in the alkene

bond breaks heterolytically, forming a Br- ion

Question 3

In an addition reaction, the closest Br atom acts as an electrophile and accepts a pair of electrons from the C-C bond in the alkene

The Br-Br bond breaks heterolytically, forming a Br- ion

This results in the formation of a………

Answer 3

highly reactive carbocation intermediate which reacts with the Br- (nucleophile)

Question 4

he stability of the carbocation intermediate is as follows

Answer 4

tertiary > secondary > primary When more than one carbocations can be formed, the major product of the reaction will be the one that results from the nucleophilic attack of the most stable carbocation.

D