Patent GB-544673-A (GB)
Title: Improvements in and relating to chromium containing azo dyestuffs
IPC: C09B45/48
Filed: 1939-12-27
Abstract: 544,673. Dyes. COMPAGNTE NATIONALE DE MATIERES COLORANTES ET MANUFACTURES DE PRODUITS CHIMIQUES DU NORD REUNIES ETABLISSEMENTS KUHLMANN. Dec. 27, 1939, No. 32858. Convention date, Jan. 21. [Classes 2 (iii) and 15 (ii)] Azo dyes, soluble chromium compounds of. The secondary chromium complex of the azo dye, anthranilic acid# 1 - (4<SP>1</SP> - sulpho) phenyl - 3 - methyl - 5 - pyrazolone, is obtained by heating the primary chromium complex, or the free dyestuff acid and a chromium salt, in a solution at least acid to Congo red, until the secondary complex is formed and crystallizes out from the solution without salting out or evaporation to dryness. The ch oming and the acid treatment may be performed successively in the same or different media or the end of the chroming to produce the primary complex may be effected in a medium at least acid to Congo red. Advantageously, any salts present are removed from the unchromed dyestuff before the chroming treatment. The products dye wool, artificial fibres of protein, skins; hides or leather from an acid bath ; those soluble in organic solvents may be used for colouring varnishes, plastic masses, waxes or soap. In examples, (1) the mono-sodium salt of the parent dyestuff is heated for 6 hours under reflux with an aqueous solution of chromium formate and the resulting primary complex is salted out and subjected to the action of N/2 sulphuric acid at the boiling point, whereupon the secondary complex crystallizes out ; alternatively, the unchromed dyestuff, in the form of the free acid, may be heated for 24 hours under reflux with an aqueous solution of chromium sulphate and sulphuric acid, whereupon the secondary complex crystallizes out ; its sodium salt dyes wool from an acid bath a level bright yellow, fast to fulling, water, washing and light ; (2) the mono-sodium salt of the parent dyestuff is heated for 24 hours under reflux with an aqueous solution containing. chromium fluoride, pyridine and sulphuric acid whereupon the secondary complex crystallizes out ; its sodium salt dyes wool a level golden yellow ; (3) a solution of the mono-sodium salt of the parent dyestuff in boiling water is acidified with hydrochloric acid and barium chloride solution is added to produce the barium salt of the dyestuff, which is converted, by treatment with dilute sulphuric acid, into the free acid, which is then heated under reflux with an aqueous solution of chromium sulphate until the secondary complex crystallizes out ; its sodium salt dyes natural or artificial fibres of protein a fast golden yellow; (4) the parent dyestuff is heated for 6 hours under reflux with an aqueous solution containing chromium fluoride and pyridine and the resulting primary complex is heated for 12 hours under reflux with aqueous sulphuric acid, whereupon the secondary complex crystallizes out ; its sodium salt dyes wool from an acid bath a level clear yellow. Specifications 408,491 and 446,820 are referred to. The Specification as open to inspection under Sect. 91 comprises also the similar production of the secondary chromium complexes of the corresponding azo dyes in which the coupling component is replaced by any sulphonated pyrazolone, sulphonated naphthol or sulphonated arylide of an acylacetic acid. In additional examples, (a) the mono-sodium salt of the dyestuff, anthranilic acid# 1 : 5- naphtholsulphonic acid, is heated under reflux with an aqueous solution containing chromium sulphate and sulphuric acid until the secondary complex crystallizes out ; its sodium salt dyes wool a bright, level, fast violet ; (b) an aqueous solution of the sodium salt of the same parent dyestuff is acidified with hydrochloric acid and barium chloride is added to produce the barium salt of the dyestuff, which is converted, by treatment with sulphuric acid, into the free acid ; this is heated under reflux with a solution containing chromium hydroxide and sulphuric acid until the secondary complex crystallizes out ; its sodium salt dyes animal fibres violet ; (c) the mono-sodium salt of the dyestuff, anthranilic acid # 2-naphthol-6-sulphonic acid is treated as in (b) to obtain a secondary complex which dyes animal fibres a fast red. This subject-matter does not appear in the Specification as accepted.