Properties of Bi-phenyl - Hydrocarbon

Bi-phenyl is a colourless solid, melting point 71°C. It goes through usual electrophilic replacement reactions. As aryl set are electron withdrawing, they should comprise deactivating and m-orientating effect. Although, it has been generally given that presence of one benzene ring activates the other for electrophilic substitution and directs the incoming group to o- and p- positions. It has been specified that monosubstitution in the bi-phenyl results in the formation of para isomer like the main product.

Another unique feature of the biphenyl is the behaviour in the direction of second substitution in a monosubstituted biphenyl. The second replacement invariably includes the unsubstituted ring in the ortho and para position no matter what is the nature of substituent previously present.