The benzene can be converted into diphenyl by following two steps.
Step 1: Formation of bromobenzene from benezene
When bromine is treated with benzene in the presence of iron bromide, it follows the electrophilic substitution reaction to form bromobenzene.
Step 2: Conversion of bromobenzene to diphenyl
Taking two moles of bromobenzene formed and combining it with sodium metal in the presence of dry ether results in the formation of diphenyl. This reaction is known as Fitting reaction.