Quinone. The term quinone is a general one applied to all benzene derivatives in which two oxygen atoms take the place of two atoms of hydrogen. According to the relative position, different classes of quinones exist. When no prefix is added, however, quinone generally means Benzo-quinone, which is obtained by the action of oxidising agents upon aniline and other benzene compounds. It forms crystals of golden yellow colour, which melt at 116°, has a peculiar odour, and is easily soluble in all ordinary solvents. By reduction it yields the compound hydroquinone, which is largely employed as a developer in photography.