DIPHENYL (phenylbenzene), an aromatic hydrocarbon found in that fraction of the coal-tar distillate boiling between 24o°-3oo°C., from which it may be obtained by warming with sulphuric acid, separating the acid layer and strongly cooling the undissolved oil. It crystallizes in plates (from alcohol) melting at 7o-71° C. and boiling at 254° C. It is sometimes called phenyl benzene, having the structure C6115.CcHs. It may be prepared by passing benzene vapour through a red-hot tube; by the action of sodium on brombenzene dissolved in ether; by the action of stannous chloride on phenyldiazonium chloride; by the decompo sition of phenyldiazonium sulphate vvith warm benzene or with alcohol and copper powder, or a yield of 82% of diphenyl is obtained by heating iodobenzene with copper powder at 23o° C.
See BENZIDINE for the industrially important derivative, diparadi aminodiphenyl.