BENZOPHENONE is the simplest ketone (q.v.) in the aromatic series (see CHEMISTRY: Organic). It is structurally a diphenyl ketone, having the formula It is a di morphous substance, existing in two enantiotropic forms, one melt ing at 26° C and the other at 48° C (Th. Zincke, 1871). It boils at 306.1° C. It may be prepared by distilling calcium benzoate; by condensing benzene with benzoyl chloride in the presence of anhydrous aluminium chloride; by the action of mercury diphenyl on benzoyl chloride, or by oxidizing diphenylmethane with chromic acid. It is reduced by sodium amalgam to benzhydrol or diphenyl carbinol a stronger reducing agent, such as hydriodic acid in the presence of amorphous phosphorus converts it into diphenylmethane Potash fusion converts it into benzene and benzoic acid. With phenylhydrazine it forms a hydrazone, and with hydroxylamine an oxime, which exists in one form only; if, however, one of the phenyl groups in the oxime be substituted in any way then two stereoisomeric oximes are produced (cf. STEREOCHEMISTRY). Tetramethyl-diamino-benzo phenone or Michler's ketone, CO[C6H4N.(CH3)2]2, melting at 178°, is of technical importance in the manufacture of synthetic dyes. It is prepared by the action of carbonyl chloride on di methylaniline in the presence of aluminium chloride : -+- 2 2 = 2 HCl + CO [ (CH3) 2] 2.
(See DYES, SYNTHETIC.)