2-naphthalenesulfonic acid, 6-Amino 4-hydroxy

Interesting regioselectivities have been known for more than 100 years for azo coupling reactions with aminonaphthol derivatives such as 6-amino-4-hydroxy-2-naphthalenesulfonic acid (12.136, y-acid), 7-amino-4-hydroxy-2-naphthalenesulf-onic acid (J-acid), and 4-amino-5-hydroxy-2,7-naphthalenedisulfonic acid (H-acid). They give two types of isomeric azo compounds depending on the pH-value of the... 

Hydroxy-6-(phenylamino)-2-naphthalenesulfonic acid ( phenyl-y-acid ) 355g 6-Amino-4-hydroxy-2-naphthalenesulfonic acid ( y-acid ) (239 g of pure material), sodium hydrogen sulfite solution (25% S02 content 750 g), water (750 ml), and aniline (200 g) are heated together under reflux for 24 h. The mixture is then made alkaline with concentrated sodium carbonate solution, and the aniline is removed in steam. Acidification of the residue with hydrochloric acid precipitates the phenyl-y-acid in an almost pure state in 75-80% yield. 

Another example of manufacture in this series is the sulfonation of an aminonaphthalenesulfonic acid, followed by selected desulfonation, to make 6-amino-l,3-naphthalenedisulfonic acid (21). Thus, 2-amino-l-naphthalenesulfonic acid made by amination of 2-hydroxy-1-naphthalenesulfonic acid is added to 20 wt % oleum at ca 35°C. At this temperature, 65 wt % oleum is added and the charge is stirred for 2 h, is then slowly heated to 100°C and is maintained for 12 h to produce 6-amino-l,3,5-naphthalenetrisulfonic acid. The mass is diluted with water and maintained for 3 h at 105°C to remove the sulfo group adjacent to the amino group. After cooling to ca 20°C and filtration, 6-amino-l,3-naphthalenedisulfonic acid is obtained in 80% yield (55). 

The manufacture of 4-hydroxy-6-amino-2-naphthalenesulfonic acid in ca 85% of the theoretical yield has been described (76). 

Manufacture of 3-hydroxy-4-amino-l-naphthalenesulfonic acid involves the nitrosation of 2-naphthalenol, bisulfite addition, and reduction of the nitroso to the amino group by sulfur dioxide generated in situ (47). 3-Hydroxy-4-amino-l-naphthalenesulfonic acid is obtained in 80% yield. 

Hydroxy-4-[(4-oxo-2,5-cycIohexadien-1-ylidene)amino]-2-naphthalenesulfonic acid, 8C1... 

FD C Red No. 40. This monoa2o dye (5) is manufactured by coupling dia2oti2ed 5-amino-4-methoxy-2-toluenesulfonic with 6-hydroxy-2-naphtha-lenesulfonic acid. FD C Red No. 40 is also known as Allura Red or Cl Food Red 17. Its chemical identity is principally the disodium salt of 6-hydroxy-5-[(2-methoxy-5-methyl-4-sulfophenyl)a2o]-2-naphthalenesulfonic acid, which has the formula C gH 4N20gS2Na2, and mol wt 496.43. 

Naphthoresorcinol has been prepared by heating l-amino-3-hydroxy-4-naphthalenesulfonic acid or its salt in water or slightly acidic solution2 and by cyclization of ethyl phenylacetylmalo-nate 3 or of ethyl phenylacetoacetate.4 Phenylacetylmalonic ester has been prepared by condensing phenylacetyl chloride and malonic ester in ether with sodium.3... 

A particularly important class of coupling components are the aminohydroxy-naphthalenesulfonic acids. Appropriate variation of the disazo component permits the development of shades ranging from orange to black. Orange and scarlet are achieved with I-acid (6-amino-l-hydroxy-naphthalene-3-sulfonic acid) and y-acid (7-amino-1-hydroxynaphthaIcne-3-sulfonic acid), whereas H-acid (8-amino-l-hydroxynaphthalene-3,6-disulfonic acid) and K-acid (8-amino-l-hydroxy-naphthalene-3,5-disulfonic acid) derivatives are useful for red to bluish-red hues. Extremely lightfast red shades are also accessible with disazo dyes ( brown dyes ). For chemical structures see Section 3.1.5). 

In mordant dyes, phenols, naphthols, and enolizable carbonyl compounds, such as pyrazolones, are generally the couplers. As a rule, 2 1 metal complexes are formed in the afterchroming process. A typical example of a mordant dye is Eriochrome Black T (18b) which is made from the important dyestuff intermediate nitro-l,2,4-acid, 4-amino-3-hydroxy-7-nitro-l-naphthalenesulfonic acid [6259-63-8]. Eriochrome Red B [3618-63-1] (49) (Cl Mordant Red 7 Cl 18760) (1,2,4-acid — l-phenyl-3-methyl-5-pyrazolone) is another example. The equilibrium of the two tautomeric forms depends on the nature of the solvent. 

IT25, Calmagite, 3-Hydroxy-4-[(2-hydroxy-5-methyl-fhasltaio]-l-naphthalenesulfonic acid 1 -(1 -hydroxy-4- Uhyl-2-phenylazo)-2 - n aph thol -4 -sulf onic acid. C,H 4-NftS mol wt 358.38. C 56.97%, H 3.94%, N 7.82%, O B.32%, S 895%. Prepn from I -amino-2-naphthol-4-sul-loik acid and p-cresol Lindstrom, Diehl, Anal. Chem. 32, 1123(1960). 

Beilstein Handbook Reference) 7-Amino-4-hydroxy-2-naphthalenesulfonic xid Amino-naphthol sulfonic acid J BRN 2217192 EINECS 201-718-9 I acid Isogamma acid J acid Kyselina 2-amino-5-naftol-7-sulfonova Kyselina 6-amino-1-naftol-3-sulfo-nova Kyselina I NSC 31510. 

Amines, polyamines, and aminophenols that can quinonize are similarly amenable to this reaction if an oxidizing agent is added 191 4-amino-3-hydroxy-1-naphthalenesulfonic acid was obtained from 1-naphthylamine,192 and a monosulfonic acid from / -phenylenediamine.193... 

Amino-3-hydroxy-1-naphthalenesulfonic acid 1-Amino-2-naphthoi-4-suitonic acid C,oHgNO,S 116-63-2 239.248 gray nd i HgO, EtOH, bz s aik... 

The well-known dye intermediate 1,2,4-acid, or 4-amino-3-hydroxy-l-naphthalenesulfonic acid, is made by this general method from l-nitroso-2-naphthol. The reactions may be represented as follows ... 

Amino-3-hydroxybutyric acid a-Amino-P-hydroxybutyric acid L-2-Amino-3-hydroxybutyric acid. See L-Threonine 6-Ami no-4-hydroxy-5-((a,a,a-trifluoro-o-tolyl) azo)-2-naphthalenesulfonic acid, monosodium salt. See Acid red 337... 

Amino-1-hydroxy-3-sulfo-2-naphthalenyl) azo)-3-((4-((4-amino-6 (or 7)-sulfo-1-naphthalenyl) azo) phenyl) azo)-4-hydroxy-2-naphthalenesulfonic acid, trisodium salt. See Direct black 80... 

Dimethyl-5-sulfophenyl) azo]-4-hydroxy-1-naphthalenesulfonic acid disodium salt. See Cl 14700 Ponceau SX FD C Red No. 4 N,N-Dimethyl-N-(3-sulfopropyl)-1-decanaminium hydroxide, inner salt N,N-Dimethyl-N-(3-sulfopropyl)-1 -dodecanaminium hydroxide, inner salt. See Lauryl sultaine Dimethyl (3-sulfopropyl) tetradecyl ammonium hydroxide, inner salt. See N,N-Dimethyl-N-myristyl-N-(3-sulfopropyl)-ammonium betaine N,N-Dimethyl-N-(3-sulfopropyl)-3-[[(3a,5p,7a,12a)-3,7,12-trihydroxy-24-oxocholan-24-yl]amino]-1-propanaminium inner salt. See 3-r(3-Cholamidopropyl) dimethylammonioj-1-propanesulfonate Dimethyl sulfoxide... 

Synonyms 6-((7-Amino-1 -hydroxy-3-sulfo-2-naphthalenyl) azo)-3-((4-((4-amino-6 (or 7)-sulfo-1-naphthalenyl) azo) phenyl) azo)-4-hydroxy-2-naphthalenesulfonic acid, trisodium salt Cl 31600 Cl direct black 80 Diazophenyl black BW 2-Naphthalenesulfonic acid, 6-((7-amino-1 -hydroxy-3-sulfo-2-naphthalenyl) azo)-3-((4-((4-amino-6 (or 7)-sulfo-1-naphthalenyl) azo) phenyl) azo)-4-hydroxy-, trisodium salt Phenazo black OB Empihcai C36H26N8O11S3 3Na Properties Bluish-bik. to bIk. powd. odorless sol. 1-10 mg/ml in water sol. < 1 mg/ml in DMSO, 95% ethanol, acetone m.w. 911.81 m.p. > 300 C Precaution Probably combustible incompat. with oxidizing agents, reducing agents Hazardous Decomp. Prods. Heated to decomp., emits toxic fumes of NOx Storage Store under ambient temps. 

Synonyms 4-Amino-3-((4 -((1 -hydroxy-4-sulfo-2-naphthalenyl) azo)-3,3 -dimethoxy (1,1 -biphenyl)-4-yl) azo)-1-naphthalenesulfonic acid, disodium salt Azo violet Cl 24105 Cl direct violet 32 Cl direct violet 32 disodium salt... 

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