Patent GB-340262-A (GB)
Title: Process for the manufacture and production of dibenzanthrones and isodibenzanthronescontaining chlorine and bromine
IPC: C09B3/32
Filed: 1929-06-21
Abstract: Dibenzanthrones and isodibenzanthrones containing substantial amounts of both chlorine and bromine are made by treating parent materials containing one of these halogens with the other halogen, or agents supplying the same, or by treating unhalogenated parent materials simultaneously with both halogens, or agents supplying the same, in the absence of any diluting medium or in any inorganic diluting medium, which may have acid, neutral or alkaline reaction.  As inorganic diluting media, water, chlorsulphonic acid, sulphuric acid, oleum, methylsulphuric acid, pyrosulphuric acid, persulphuric acid, phosphoric acid, liquid sulphur dioxide, phosphorus oxychloride, and sulphuryl chloride, and mixtures thereof, are specified.  The acid set free during the reaction may be neutralized by addition of alkalies or salts of alkali metals and weak acids, or the concentration of hydrogen ions may be kept constant by the addition of buffer compounds. The usual halogen transferrers, such as iodine, sulphur, selenium or metals and metal compounds, e.g. iron, copper, mercury and antimony, may be employed.  Dibenzanthrones and isodibenzanthrones produced by halogenation in organic solvents, or in the absence of solvents, or dibenzanthrones chlorinated in chlorsulphonic acid (Specification 212,145, [Class 2 (iii), Dyes &c.], may be used as parent materials, as well as the bromo derivatives prepared according to Specifications 325,525 and 329,263, [both in Class 2 (iii), Dyes &c.].  The products may be p  purified by crystallization or by means of their oxonium salts, or by treating their aqueous pastes with oxidizing agents, e.g. hypochlorites.  In examples, (1) the dyestuff obtained by alkylating Bz2 : Bz2'-dihydroxydibenzanthrone with the chlorethyl ester of p-toluenesulphonic acid is brominated in chlorsulphonic acid in presence of antimony; the product, containing chlorine and bromine, dyes fast green blue shades, (2) dichlorisodibenzanthrone, made by treating pure isodibenzanthrone with sulphurylchloride, is brominated in chlorsulphonic acid in the presence of antimony; the product dyes fast blue violet shades, (3) dibenzanthrone is chlorinated with a solution of chlorine in aqueous caustic soda, and bromine is passed into the reaction mixture; the product dyes navy blue shades, (4) dibromdibenzanthrone (made by brominating in nitrobenzene in presence of iron and iodine) is treated with chlorine in dilute oleum; the product dyes navy blue shades, (5) dibenzanthrone is treated with phosphorus pentachloride and bromine in phosphoric acid; the product dyes navy blue shades, (6) 6 : 6'-dichlorisodibenzanthrone, made by alkaline condensation of 6 : Bz1'-dichlorbenzanthrone, is brominated in dilute oleum in presence of arsenic; the product dyes clear blue violet shades, (7) monochlordibenzanthrone (made by chlorination in chlorsulphonic acid in presence of antimony) is ground with bromine in a ball mill; the product dyes fast blue shades, and (8) an aqueous paste of dibenzanthrone is brominated, and the reaction mixture is made weakly alkaline with caustic soda solution and treated with sodium hypochlorite; the product dyes navy blue shades. Specification 284,656, [Class 2 (iii), Dyes &c.], also is referred to.