Biphenyl
Biphenyl (or diphenyl or phenylbenzene or 1,1′-biphenyl or lemonene) is an organic compound that forms colorless crystals.
It has a distinctively pleasant smell. Biphenyl is an aromatic hydrocarbon with a molecular formula (C6H5)2. It is notable as a starting material for the production of polychlorinated biphenyls (PCBs), which were once widely used as dielectric fluids and heat transfer agents.