Patent GB-311047-A (GB)
Title: Improvements in the manufacture and production of condensation products of the benzanthrone series
IPC: C09B5/24
Filed: 1928-03-16
Abstract: 311,047. Johnson, J. Y., (I. G. Farbenindustrie Akt.-Ges.). March 16, 1928, Benzanthrone derivatives.-Alkali-soluble condensation products of the benzanthrone series are obtained by treating Bz-1-benzanthronylthioglycollic acid, or its derivatives or substitution products having free 2-positions, with alkaline condensing agents. The products are converted into green-blue vat dyes by treating with mild oxidizing agents, for example, by treating the alkaline solutions with air or other oxidizing agents, such as ammonium persulphate, or by heating the dried intermediate products with nitrobenzene or with inert solvents, such as trichlorbenzene, in presence of air, or by warming their solutions in concentrated sulphuric acid. The esters, amides and nitriles of the thioglycollic acids, and also their oxidation products (presumably sulphoxides) having free 2-positions, may also be used as parent materials. According to examples, (1) Bz-1-benzanthronylthioglycollic acid is fused with caustic potash or a mixture of caustic potash and caustic soda in the presence or absence of water, the melt is diluted with water, filtered and treated with hydrochloric acid to precipitate the intermediate product, which may be converted into the vat dye by drying and boiling with nitrobenzene, or the vat dye may be obtained directly by passing air through the filtered alkaline solution; 6-chlor-Bz1-benzanthronylthioglycollic acid (obtained by brominating 6-chlorbenzanthrone in nitrobenzene, converting the resulting 6-chlor- Bz1-brombenzanthrone into the sodium salt of 6-chlor-Bz1-benzanthronemercaptan by heating with sodium sulphide and sulphur in alcoholic solution, and treating the product with sodium monochloracetate in aqueous solution) gives similar products, (2) Bz-1-benzanthronylthioglycollic acid is heated with caustic potash in pyridine, and the product converted into the vat dye as described in Example 1, (3) the ethyl ester of Bz-1-thioglycollic acid (obtained by heating the acid with ethyl alcohol and concentrated sulphuric acid) is heated with caustic potash in pyridine, and the intermediate product converted into the vat dye as described in Example 1; other esters may be used instead of the ethyl ester; (4) Bz-1- benzanthronylthioglycollonitrile (made by condensing sodium Bz-1-benzanthronylmercaptide with monochloracetonitrile) and Bz-1-benzanthronylthioglycollicamide (made by treating the nitrile with sulphuric acid at ordinary temperatures) are employed in a similar manner; (5) the oxidation product of Bz-1-benzanthronylthioglycollic acid (obtained by oxidizing the acid with the amount, calculated for the production of a sulphoxide, of ammonium persulphate, or concentrated nitric acid, or hydrogen peroxide in concentrated sulphuric acid, or by treating in aqueous solution of an alkali salt of the acid with sodium hypochlorite) is heated with caustic potash and water or ethyl alcohol; the product can be converted into a vat dye in the manner described in Example 1, and (6) the methyl ester of the oxidation product referred to in the preceding example (obtained by treating the oxidation product with methyl alcohol and sulphuric acid) is heated with caustic potash in pyridine, and the product converted into a vat dye in the manner described in Example 1; the amide and nitrile of the oxidation product (obtained by treating the amide or nitrile of Bz1-benzenthronylthioglycollic acid with ammonium persulphate or hydrogen peroxide in concentrated sulphuric acid) may be similarly treated.