Abstract: The present invention relates to an improved continuous process for the preparation of mononitro-aromatic compounds which comprises (1) nitrating a reactive aromatic compound in the absence of sulphuric acid until mono-nitration is essentially complete, said nitration being carried out in 40 to 68% strength by weight nitric acid, (2) separating mechanically the nitration reaction mixture into an inorganic phase and an organic phase, (3) washing of the organic phase with water and dilute alkali solution and subsequent separation of the unconverted starting material end of the adhering water by means of rectification (4) feeding the inorganic phase and, if necessary, the wash water of the first water wash of the organic phase, to a rectification column in which (a) water is withdrawn over the top (b) optionally a fraction which has a lower nitric acid content than the feed is withdrawn from a sidestream takeoff in the rectifying section of the column and (c) a fraction which has a higher nitric acid content tha

Abstract: Dinitronaphthalenes are prepared by reacting nitronaphthalene at temperatures of from 20.degree. to 50.degree. C which 60 to 80% strength by weight aqueous nitric acid. The resulting dinitronaphthalene is separated off in a known manner and the residual nitric acid is enriched until a concentration of 60 to 80% by weight is reached and is then recycled to the reaction.