In the following reaction sequence, structures of A and B are, respectively

Initially electrophilic addition reaction takes place and form alcohol and alkyl bromide. Then Wurtz reaction takes place.

The Wurtz reaction is a very useful reaction in the fields of organic chemistry and organometallic chemistry for the formation of alkanes. In this reaction, two different alkyl halides are coupled to yield a longer alkane chain with the help of sodium and dry ether solution.