GB325525A - Improvements in the manufacture and production of halogen substitution products of the dibenzanthrone and isodibenzanthrone series - Google Patents

Abstract

325,525. Johnson, J. Y., (I. G. Farbenindustrie Akt.-Ges.). Aug. 21, 1928. Dibenzanthrone and isodibenzanthrone series.- Halogenated dibenzanthrones and isodibenzanthrones are obtained by treating dibenzanthrone or isodibenzanthrone or bromo derivatives thereof in any inorganic diluting medium, which may have acid, neutral or alkaline reaction, or mixtures thereof, with bromine or agents supplying bromine, in the presence of halogen transferrers if desired. Water, chlorsulphonic acid, sulphuric acid, oleum, methylsulphuric acid, pyrosulphuric acid, persulphuric acid, phosphoric acid and liquid sulphur dioxide, or mixtures thereof, are specified as diluting media, and, as halogen transferrers, iodine, sulphur, selenium, or metals such as iron, copper, mercury and antimony, and their compounds, may be used. The acid set free during the reaction may, if desired, be wholly or partially neutralized by adding alkalies or weak acid salts of alkali metals, or the concentration of hydrogen ions may be kept constant by the addition of buffer compounds. When chlorsulphonic acid is employed at diluting medium, dyestuffs containing chlorine as well as bromine are obtained at temperatures above 50‹ C., particularly in the presence of halogen transferrers, while at lower temperatures little or no chlorine enters the molecule. The products dye in blue to violet shades. Dibenzanthrones and isodibenzanthrones brominated in any other way, for example inorganic solvents, may be further brominated by the process of the invention. Numerous examples are given in which chlorsulphonic acid, sulphuric acid, oleum, phosphoric acid, and water, with or without the addition of sulphuric acid or sodium hydrate, are employed as diluting media, in the presence of sulphur, selenium, iodine, antmony, manganese, arsenic, mercury, or iron sulphate as catalysts, or in some cases in the absence of catalysts; the products include mono-, di-, tri-, tetra-, penta and hexabromo and higher brominated derivatives of both dibenzanthrone and isodibenzanthrone, as well as monochlordibrom, dichlortribrom, and dichlortetrabrom derivatives obtained by the use of chlorsulphonic acid as diluting medium. The products may be purified by means of their oxonium salts or by treating them with oxidizing agents, such as hypochlorites.