Patent GB-443722-A (GB)
Title: Improvements in the manufacture and production of azo dyestuffs containing metal
IPC: E04F17/08
Filed: 1934-08-29
Abstract: Complex metal compounds of azo dyes are made by splitting off by acid treatment the sulphonic acid group in the 4-position from the complex metal compounds of the azo dyes: (1) o-hydroxy-, o-carboxy- or o-alkoxyamines --> 1-naphthol-4-sulphonic acid or its derivatives having a free 2-position; (2) 2-amino-1-naphthol-4-sulpho acids--> o-coupling hydroxy components.  The azo group in the dyestuff molecule is present in the 2-position of the naphthalene residue. The splitting off of the sulphonic group may be partial, whereby mixtures are obtained. In the case of dyestuffs containing sulphonic groups in the 4-positions of both components, either one or both sulphonic groups may be split off.  Those dyestuffs which still contain sulphonic acid groups may be used for dyeing wool, silk, leather and lacquers whilst the unsulphonated products are pigment dyes. In examples (1) and (2) the chromed dyestuff 1-methoxy-2-amino-4-chlor-5-nitrobenzene --> 1-naphthol-4; 8-disulphonic acid is heated under pressure with sulphuric acid (greenish blue on animal fibres with a good shade in artificial light); with a shorter period of heating a mixture dyeing navy-blue is obtained; (3) the dyestuff 4-chloro-2-amino-1-methoxybenzene --> 1-naphthol-4: 8-disulphonic acid is chromed with chromium hydroxide and sulphuric acid and the moist acid product heated with water under pressure (reddish blue); (4) the chromium compound of the dye 1-amino-2-naphthol-4-sulphonic acid --> 1-naphthol-4: 8-disulphonic acid is treated with hydrochloric acid (blue); (5) the copper compound of the dyestuff 4-chloro-2-aminophenol-6-sulpho acid --> 1-naphthol-4-sulphonic acid is treated with 4 per cent sulphuric acid (violet on wool); (6) the chromium compound of the dyestuff 2-amino-1-naphthol-4: 8-disulphonic acid --> b -naphthol is treated with sulphuric acid (blue on wool, silk and leather and also suitable for colouring lacquers derived from cellulose esters and ethers); (7) the dyestuff 2-amino-1-naphthol-4: 8-disulphonic acid --> 1-phenyl-3-methyl-5-pyrazolone is treated with chromium oxide and formic acid and the filtered product containing a slight amount of acid is heated under pressure with water (Bordeaux-red on wool and p silk); (8) the dyestuff 2 - amino - 1 - naphthol - 4: 8-disulphonic acid --> 1-(3<1>-sulphophenyl)-3-methyl - 5 - pyrazolone is heated under pressure in the chromium formate; sufficient acid is generated to remove the 4-sulphonic acid group(red-violet); (9) the dyestuff 2-amino-1-naphthol-4-sulphonic acid --> 1-(3<1>-sulphophenyl) - 3 - methyl - 5 - pyrazolone is chromed with chromium oxide and formic acid and the product treated as in (3) (reddish blue); (10) the dyestuff 2-amino-1-naphthol-4-sulphonic acid --> 2-naphthol-4-sulphonic acid is chromed with chromium oxide and formic acid and the product treated as in (3) (grey-blue).  It is also stated that a dyestuff of symmetrical structure is obtained by converting the dyestuff 2-amino-1-naphthol-4: 8-disulphonic acid --> 1-naphthol-4: 8-disulphonic acid into its complex metal compound and splitting off the two 4-sulphonic groups.  Specification 358,146 is referred to.