GB371420A - Improvements in and relating to the production of vat dyestuffs - Google Patents

Abstract

2-Amino-3-fluoroanthraquinone (Specification 365,165) is acetylated, converted into the disulphuric ester of the corresponding 2-acetylamino-3-fluoro-9 : 10-dihydroanthraquinone, by means of a tertiary base and sulphur trioxide, in presence of a metal, and the ester after hydrolysis of the acetyl group, isolated. The latter product is oxidized in alkaline medium to give the tetrasulphuric ester of 3 : 3<1>-difluorotetrahydrodianthraquinoneazine, which on acidification gives the disulphuric ester of 3 : 3<1>-difluoroanthraquinone - anthrahydroquinone-dihydroazine. The tetrasulphuric ester may be converted on textile fibres or in substance by means of development with an acid oxidizing agent, into the 3 : 3<1>-difluorodianthraquinone-dihydroazine. According to examples (1) 2-amino-3-fluoroanthraquinone is acetylated, treated with pyridine-sulphur trioxide and copper and hydrolysed to give the disulphuric ester of 2-amino-3-fluoro-9 : 10-dihydroanthraquinone; (2) the product is oxidized with sodium hypochlorite, followed by the addition of partly neutralized sodium bisulphite and the product separated with potassium chloride; (3) the product of example (2) is treated with alcoholic potash to give the tetrasulphuric ester of 3 : 3<1>-difluorotetrahydrodianthraquinoneazine, which on acidifying gives the disulphuric ester of 3 : 3<1>-difluoroanthraquinoneanthrahydroquinone-dihydroazine; (4) cotton is padded with the di- or tetrasulphuric esters of the last example and developed according to example (3) of Specification 350,499: when development is carried out in substance, the product is 3 : 3<1>-difluorodianthraquinone dihydroazine. Specification 334,902, [Class 2 (iii), Dyes &c.], also referred to.