GB289980A - Improvements in the manufacture and production of vat dyestuffs - Google Patents

Abstract

289,980. Johnson, J. Y., (I. G. Farbenindustrie Akt.-Ges.). Feb. 14, 1927. Benzanthrone dyes.-Green vat dyes are obtained by fusing with caustic alkali under mild conditions, the aminobenzanthrone obtained by reducing the nitrobenzanthrone described in Example 2 of Specification 12518/06, or those substitution products of the said aminobenzanthrone which contain exchangeable substituents in the Bz 1-position, or the N-acy-1 derivatives thereof. The products may be converted into brown vat dyes by treating them with oxidizing agents either in substance or on the fibre, or the nitrobenzanthrone may be fused directly with caustic alkali to yield a brown vat dye. In examples (1) the aminobenzanthrone itself, its Bz1-brom derivatives, the acetylamino-Bz1-thiocresylether, and the amino-Bz1-mercaptomethylether are fused with caustic potash and ethyl alcohol to yield green dyes, (2) the dye obtained from the aminobenzanthrone is oxidized with chromic acid and the crude product purified by treatment with dilute hypochlorite solution, (3) the nitrobenzanthrone is fused with alcoholic potash and the product purified by treating with hypochlorite; the resulting dyesttiff dyes cotton a fast brown shade which changes to a reddish orange when chlorinated on the fibre, and (4) cotton is dyed from the warm hydrosulphite vat with the dye obtained from the aminobenzanthrone, and is then treated with a dilute solution of bleaching powder; the original green shade changes to a rich brown. Benzanthrone derivatives. - The above-mentioned amino-Bz1-brombenzanthrone is obtained by brominating the acetyl derivative of the said aminobenzanthrone in glacial acetic acid and saponifying the product. The acetylaminobenzanthrone-Bz1-thiocresylether is obtained by condensing the acetylamino-Bz1-brombenzanthrone with p-thiocresol. The amino-Bz1-benzanthronemercaptomethylether is obtained by methylating the sodium compound of amino-Bz1-benzanthrone-mercaptan, which is a by-product in the reduction of the nitrobenzanthrone with sodium sulphide.