Patent GB-340009-A (GB)
Title: Improvements in the manufacture and production of dyestuffs of the t?trazine series
IPC: C09B27/06
Filed: 1929-08-19
Abstract: Azo dyes; lakes.-Azo dyes of the tartrazine series are obtained by a selection of the reacting components such that the finished dyestuff is substituted in the 1- and 4- positions of the pyrazolone ring by a phenyl and a phenylazo radicle respectively which each contain two sulpho groups, and such that of the four sulpho groups one pair occupies the 5\sv- and 5"- positions while the other pair occupies either the 2\sv- and 2"- or the 3\sv- and 3"- positions, or, if each of the phenyl radicles carries a methyl group in the 2\sv- and 2"- positions, the second pair of sulpho groups occupies the 4\sv- and 4"- positions.  The method of preparation may be either (1) condensing 1 mol. of sodium dihydroxytartrate with 2 mols. of a phenyl- or tolyl-hydrazine-5-sulphonic acid carrying a further sulpho group in positions as defined above, or (2) coupling a pyrazolone, obtainable by condensation of 1 mol. of oxalacetic ester with 1 mol. of a phenyl-or-o-tolyldisulphonic acid as defined above, with the corresponding phenyl-or-o-tolyl-diazonium compound containing two sulphonic groups.  The products give greenish yellow dyeings fast to water and are specially suitable for printing on paper.  They are convertible into lakes by the usual methods.  The lakes of the product derived from 2-aminotoluene-4 : 5-disulphonic acid are specially valuable for wall papers and are fast to over-printing. The products derived from aniline-2 : 5- and 3 : 5-disulphonic acids are specially fast to light and are suitable for dyeing wool.  The following examples are specified.  (1) Sodium dihydroxytartrate is heated with an aqueous suspension of the hydrazine of 2-aminotoluene-4 : 5-disulphonic acid.  (2) The diazo compound from 2-aminotoluene-4 : 5-disulphonic acid is coupled with 1-(2\sv-methylphenyl-4\sv : 5\sv-disulphonic acid)-5-pyrazolone-3-carboxylic acid.  (3) Sodium dihydroxytartrate is heated with an aqueous paste of phenylhydrazine-3 : 5-disulphonic acid; the product gives on wool very greenish-yellow dyeings, fast to light, and is convertible into colour lakes by treatment with metallic salts.  (4) The same product is obtained by coupling the diazo compound from aniline-3 : 5-disulphonic acid with 1-(3\sv : 5\sv-disulpho) phenyl-5-pyrazolone-3-carboxylic acid; a similar product is obtained by using as coupling component the corresponding 5-pyrazolone-3-carboxylic ester.  (5) Sodium dihydroxytartrate is heated with phenylhydrazine-2 : 5-disulphonic acid in dilute sulphuric acid.  (6) The same product is obtained by coupling the diazo compound from aniline-2 : 5-disulphonic acid with 1-(2\sv : 5\sv-disulpho) phenyl-5-pyrazolone-3-carboxylic acid; a similar product is obtained by using as coupling component the corresponding 5-pyrazolone-3-carboxylic ester.  Specifications 765/97 and 5693/93, [both in Class 2, Acids and salts, Organic &c.], are referred to. Pyrazolones.-The above pyrazolone-carboxylic acids and esters are obtainable by condensation of phenylhydrazine-2 : 5-or 3 : 5-disulphonic acid or 2-methylphenylhydrazine-4 : 5-disulphonic acid with oxalacetic ester.  Phenylhydrazine-3 : 5-disulphonic acid and 2-methylphenylhydrazine-4 : 5-disulphonic acid are obtainable by treating the corresponding diazobenzenedisulphonic acids with sodium sulphite and decomposing the resulting hydrazosulphonic acids with sulphuric acid.