Patent GB-360776-A (GB)
Title: Manufacture of vat-dyestuffs
IPC: C09B5/06
Filed: 1931-02-26
Abstract: Benzanthronepyrazolanthrone vat dyestuffs are made by treating a halogen derivative of a benzanthronepyrazolanthrone with an oxidizing agent and alkylating the oxidation product thus obtained.  Mono- and dihydroxy or keto-derivatives are formed. The latter may be converted to hydroxy compounds with e.g. sulphurous acid.  In general the halogenbenzanthronepyrazolanthrone is added to sulphuric acid which may contain boric acid, the solution oxidized with pyrolusite, manganic sulphate or nitric acid and the ketonic oxidation product treated with bisulphite to form the hydroxy compound which is alkylated with p-toluenesulphonic acid methylester or a dialkylsulphate.  In examples (1) monochlorbenzanthronepyrazolanthrone (from benzanthronepyrazolanthrone, hydrochloric acid and a chlorate) is converted into a monochlor-dimethoxy derivative, (2) dichlorbenzanthronepyrazolanthrone (obtained as in (1) using higher temperature) is treated to give a dichlordimethoxy or diethoxy derivative; the vat dyes cotton greenish blue, (3) a similar product is made from the dichloro body obtained from benzanthronepyrazolanthrone and sulphuryl chloride in nitrobenzene; (4) trichlorobenzanthronepyrazolanthrone (obtained by chlorination in trichlorobenzene near boiling point) yields a trichlor-dimethoxy derivative which dyes in a blue vat greenish blue tints; a pentachloro derivative is obtained on further chlorination of the starting material which may be treated as above but the product has small tinctorial power; (5) treatment of the trichlorobenzathronepyrazolanthrone obtained by chlorinating in nitrobenzene in presence of antimony pentachloride yields a similar product to (4); (6) trichlorobenzanthronepyrazolanthrone (obtained by using chlorosulphonic acid, iodine and carbon tetrachloride) is treated to give a trichlorodimethoxy derivative similar to (4); the hexachloro derivative obtained by chlorination in chlorsulphonic acid in presence of iodine may also be oxidized and methylated; (7) benzanthrone-8-chlorpyrazolanthrone (by condensing 8-chlorpyrazolanthrone with Bz-1-brombenzanthrone) gives a chlorodimethoxy derivative; (8) dibromobenzanthronepyrazolanthrone (by bromination in presence of iron) gives a dibromodimethoxy derivative; (9) similar products are obtained by treating the dibromo derivatives obtained by bromination in chlorsulphonic acid in presence of iodine or in glacial acetic acid; (10) dibromomonochlorobenzanthronepyrazolanthrone (obtained by causing 3 atomic proportions of bromine to act on the dichloro derivative made using sulphuryl chloride in chlorsulphonic acid) gives a dibromomonochlorodimethoxy derivative; (11) the starting material of (2) is oxidized with pyrolusite in sulphuric acid containing boric acid and the mono hydroxy derivative obtained by treatment with bisulphite which gives a dichlormonomethoxy derivative on methylation; (12) using the starting material of (6) a trichloromonomethoxy derivative is similarly obtained.  The Specification as open to inspection under Sect. 91 (3) (a) comprises also aralkoxy derivatives.  This subject-matter does not appear in the Specification as accepted.