main application: in a eutectic mixture with diphenyl ether, as a heat transfer agent. This mixture is stable to 400 °C.

Biphenyl does undergo sulfonation which, followed by base hydrolysis, produces p-hydroxybiphenyl and p,p´-dihydroxybiphenyl, which are useful fungicides. In other substitution reactions, it undergoes halogenation. Polychlorinated biphenyls