GB671814A - Improvements in or relating to water-soluble dyestuffs derived from sulphuretted tetracene (naphthacene) - Google Patents

Abstract

Dyes are made from an unvattable green, pigment of the formula <FORM:0671814/IV (c)/1> (obtainable by the action of sulphur or sulphur chloride on naphthacene or by the action of sulphur on a halogenated naphthacene) by an oxidizing salification performed by any of the general methods known for converting a leucobase into salts. The oxidizing salification may be effected by (1) an oxidizing agent in an acid medium; (2) an oxidizing acid in concentrated solution; (3) a salt of a noble metal; (4) a holoquinoid salt of an organic base; (5) an ester of a mineral acid, or (6) a halogen. The products are used for dyeing, printing, or foularding fabrics such as cotton, natural or regenerated cellulose, or natural silk, and may be split on the fibre to give unvattable green pigments by hydrolysing or reducing agents. The products appear to consist of a positively-charged sulphuretted naphthacene radical joined by electrovalent links to one anion (red salts) or two anions (yellow salts). In examples, sulphuretted naphthacene is reacted with (1) lead dioxide (or manganese dioxide or hydrogen peroxide) and 45 per cent sulphuric acid, giving a yellow sulphate which forms on heating an insoluble brown-red sulphate; (2) concentrated sulphuric acid, to give the same sulphates as in (1); (3) concentrated nitric acid, alone or mixed with glacial acetic acid; (4) chlorine or bromine in trichlorbenzene; (5) air and trichloracetic acid to give a yellow trichloracetate; (6) air and hydrochloric acid, preferably with sodium nitrite, to give a red monochloride; (7) lead dioxide (or manganese, dioxide, hydrogen peroxide, or air in presence of sodium nitrite), and acetic acid to give a monoacetate; (8) methyl sulphate in trichlorbenzene; (9) the yellow sulphate of (1) above to give with the sulphuretted tetracene the red monosulphate; (10) silver sulphate, to give the red monosulphate; (11) the dinitrate of dimethyl-p-phenylene diamine. Further examples describe the dyeing of cotton, viscose, or natural silk with the product of (4) or (5) above, followed by treatment of the dyed material with sodium hydrosulphite, or with sodium carbonate, with or without soap. Reference is also made to the use of perchloric and formic acids.