7-Amino-l-naphthol-3-sulfonic acid

A similar argument can be applied to the results of later work by Idelson et al.i9 In this they prepared the chromium complex (133) by interaction of the 1 1 chromium complex of 1-phenyl-3-methyl-4-(2-hydroxy-4-cyanonaphth-l-ylazo)-5-pyrazolone and diethylenetriamine and by reaction of the azo compound with [Cr(CO)3dien]. Identical products were obtained and, since the diethylenetriamine occupies9 a facial position in [Cr(CO)3dien], it was concluded that the complex (133) had a facial configuration. Similarly, the reported77 separation of isomeric 2 1 chromium complexes of 2-amino-6-(2-hydroxy-6-nitro-4-sulfonaphth-l-ylazo)-5-naphthol-7-sulfonic acid is... 

In the stepwise synthesis of the unsymmetrical complex dye 13 [ 70236-60-1] [10], the azo dye made from diazotized l-amino-2-hydroxy-5-nitrobenzene and 1-phenyl-3-methyl-5-pyrazolone and the 1 1 chromium complex obtained from 6-nitro-l-diazo-2-hydroxynaphthalene-4-sulfonic acid and 2-naphthol are heated together at 80 °C for 5 h. The adduct is salted out with NaCl. A black powder is obtained that dyes wool and leather in dark brown shades. The resulting colors are fast, particularly on shrink-resistant wool. 

J Acid n Fusion product of beta-naphthylamine-3,6-bisulfonic acid with caustic. Used in the manufacture of dyes. Also known as 2-Amino-5-Naphthol-7-Sulfonic Acid and 6-Amino-l-Naphthol-3-Sulfonic Acid. 

Technologically, the most important examples of such couplers are 1-naphthylamine, 1-naphthol, and sulfonic acid derivatives of 1-naphthol (Fig. 2). Of great importance in the dyestuff industry are derivatives of l-naphthol-3-sulfonic acid, such as H-acid (8-amino-l-naphthol-3,6-disulfonic acid [90-20-0])... 

Fig. 5. Direct red dyes, (a) Direct Red 81 described ia text (68) (b) Direct Red 2 (o-toLidiae coupled to two moles of naphthionic acid) (69) (c) Direct Red 23 (aniline coupled to 6,6 -ureylenebis-l-naplitliol-3-sulfonic acid with a second coupling with j aminoacetanilide) (70) and Direct Red 80 (2 mol 6-amino-3,4 -azobenzenedisulfonic acid coupled twice to 6,6 -ureylenebis-l-naphthol-3-sulfonic acid) (73). Direct Red 24 (4-aniino-y -toluenesulfonic acid coupled under acidic conditions to 6,6 -ureylenebis-l-naphthol-3-sulfonic acid followed by an alkaline coupling of o-anisidine) (71) (d) Direct Red 72 (Broenner s acid, ie, 6-artiino-2-naphthalenesulfonic acid coupled under acidic conditions to 6,6 -ureylenebis-l-naphthol-3-sulfonic acid followed by an...

Azo Dyes. The dye obtained by coupling diazotized 4-(2-sulfooxyethylsulfonyl)ani-line with l-amino-8-naphthol-3,6-disulfonic acid at pH 1 - 2 is coupled at pH 6 - 7 with a diazonium compound synthesized from the condensation product derived from l,3-diaminobenzene-6-sulfonic acid and 2,4,6-trifluoro-5-chloropyrimidine. The crude material is salted out of the solution and isolated. This product (24) gives a blue solution in water and dyes cotton in a marine blue to black color ... 

The small increase of the reaction rate for the 1-position (dotted line) at pH 9.5 to 10.0 reflects experimental results obtained by Ikeda et al. 255-257) paper these authors determined the relative rate constants for azo coupling reactions of 6-amino-l-naphthol-3-sulfonic acid (J-acid, 153) with 4-methyl- and 4-chlorobenzenediazonium ions in competitive experiments to the azo coupling reaction of l-naphthol-4-sulfonic acid at pH 5.5-9.1. The rate at the 2-position of J-acid, i.e. the reaction directed by the O -group, is 300-4000 times faster than that at the 5-position, which is directed by the amino group. These authors made two interesting observations ... 

The Colour Index (up to June 1991) lists 21 direct violets with disclosed chemical constitutions. Commercially important are Cl Direct Violet 9 [6227-14-1] (79) (Cl 27885) (sulfanilic acid coupled to cresidine followed by alkaline coupling to IV-phenyl J-acid) and Cl Direct Violet 66 [6798-05-4] (80) (Cl 29120) (a copper complex of 2-amino-l-phenol-4-sulfonamide (2 mol) coupled to 6,6,-iminobis- l-naphthol-3-sulfonic acid). 

Naphthol-7-sulfonic acid, 2-amino-6-(2-hydroxy-6-nitro-4-sulfonaphth-l-ylazo)-ehromiura complexes geometrical isomerism, 70 stereochemistry, 62... 

Amino-2-(2-hydroxy-3,5,6-trichlorophenylazo)-l-naphthol-5-sulfonic acid... 

Hydroxy-4-[ 4-methylpheny[)amino]-6-[ 2,3,5-trichloro-6-hydroxyphenyl)azo]-l-naphthalenesulfonic acid. 8-p-Toluidino-2- 3,5,6-trichloro-2-hydroxyphenylazo)- 1-naphthol-5-sulfonic acid. Omega chrome blue green BL. Metomega chrome blue green BL. C.I. 17650... 

The azo compounds are important chromophores because of extended electronic delocalisation between the two aromatic rings via the azo bond. The darkness of the dye is enhanced by extensive delocalisation combined with several sulfonic acid groups which function as auxochromes. An example is provided by Naphthol Blue Black B (10), prepared from 8-amino-l-hydroxynaphthalene-3,6-disulfonic acid (H-acid) (11) by coupling it in the 7-position with diazotised p-nitroaniline in acidic solution and subsequently coupling in the 2-position with diazotised aniline in alkaline solution (Scheme 3). The H-acid (11) is a very versatile component in dye manufacture because it can couple with diazonium salts in either the 2-position or 7-position depending on the pH of the reaction medium, as indicated in Scheme 3. 

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