2-Naphthylamine-l-sulfonic acid

Benzopurpurin 4B (also cotton red 4B or sultan 4B) Schultz No. 268, sodium salt of o-toluidinedisazo-bi-l-naphthylamine-4-sulfonic acid. 

Naphthylamine-l,5-disulfonic acid l-Naphthylamine-4-sulfonic acid l-Naphthylamine-5-sulfonic acid... 

Typical primary amines which undergo such nitrosation are m-toluidine, p-xylidine, m-anisidine, 2-amino-4-methoxytoluene, 3-amino-4-methoxy-toluene, m-aminophenol, a-naphthylamine, l-naphthylamine-2-, -6-, -7-, and -8-monosulfonic acids, and l-naphthylamine-4-monosulfonic acid (which reacts with displacement of the sulfonic acid group). The secondary amines derived from these primary amines also can be nitrosated directly (i.e., without the intermediate formation of an JV-nitroso compound which needs to be subjected to the Fischer-Hepp rearrangement). The entering nitroso group appears to substitute exclusively in the para position. 

Ion-pair HPLC (194,195) was used to separate amaranth from its subsidiary dye l-(4-sulfo-l-naphthylazo)-2-naphthol-6-sulfonic acid disodium salt (fast red E) and from its intermediates 1-naphthylamine 4-sulfonic acid (naphthionic acid) and 2-naphthol-3,6-disulfonic acid disodium salt (R-salt). Ion-pair HPLC was also used for the determination of total free and bound nonsul-fonated aromatic amines in amaranth after diazotization and coupling with R-salt (198). 

Derivation l-Naphthylamine-8-sulfonic acid is reacted with sulfuric acid to yield 1-naphthylamine-4,8-disulfonic acid further reaction with 25% oleum gives l,8-naphthosulfam-2,4-disulfonic acid, which melts at 155C with 40% NaOH. 

Nitro-l-diazo-2-naphthol-4-sulfonic acid prefers the 2-position in spite of the nitro group, and increasing alkalinity favors ortho coupling with diazophenols. 1-Naphthalenesulfamic acid [24344-19-2] (ArNHSO H) and N-nitro-1-naphthylamine [4323-69-7] (ArNHNO ) couple exclusively in the para position. The substitution of resorcinol [108-46-3] and y -phenylenediamine [108-45-2] is compHcated and has been discussed (29,30). The first azo dyes from aniline, eg. Aniline Yellow [60-09-3] (19) (Cl Solvent Yellow 1 Cl 11000) were manufactured in 1861 and Bismark Brown [10114-58-6] (20) (Cl Basic Brown 1 Cl 21000) appeared in 1863. The reaction is as follows ... 

Sulfurous acid and its salts are inexpensive reducing agents which are, however, usable only in special cases. These reagents frequently give sulfonation simultaneously with reduction (cf. the preparation of l-naphthylamine-2,4-disulfonic acid from 1-nitronaphthalene, and of l-amino-2-naphthol-4-sulfonic acid from nitroso- -naphthol, pages 178 and 201). Also, in the reduction of diazobenzene to phenylhydrazine, a N-sulfonic acid is formed first and this must be split by vigorous treatment with hydrochloric acid (see pages 96 and 128). 

N -Iodoacetylethylenediamiwo)-naphthalene-1-sulfonic acid N-(Iodoacetylaminoethyl)-5-naphthylamine-1-sulfonic acid N-(lodoacetylaminoethyl)-8-naphthylamine-l-sulfonic acid 7-(p-Methoxybenzylamino-4-nitro-benz-2-oxy-1,3-diazole N-3-Pyrene maleimide Quinacrine mustard Rhodamine B isothiocyanate... 

Derivation Sulfonation of l-naphthylamine-8-sul-fonic acid or l-naphthylamine-4,8-disulfonic acid. 

Aminonaphthalene-7-sulfonic acid 8-Amino-naphthalene-2-sulfonic acid 8-/kminonaphthalene-2-sulphonic acid 1-Amino-7-sulfonaphlhalene Cassella s acid C.l. 26135 Qeve s acid 1,7-Cleve s acid Cleve s theta-acid Delta acid EINECS 204-311-4 F acid J acid 2-Naphthalenesulfonic acid, 8-amino- 1-Naphthylamine-7-sulfonic acid 8-Naphthylamine-2-sulfonio acid NSC 4983. Used as an intermediate for azo dyes. Crystallizes as the monohydrate, soluble in H2O (0.45 g/100 ml). 

Zou et al. [1560] separated 14 phenylamine- and naphthylaminesulfonic acids (e.g., 2-aminonaphthalene-4,6,8-trisulfonic acid, l,3 diamino-4-sulfonic acid, phenylamine-2-sulfonic acid, 6-chlorophenylamine-3-sulfonic acid, naphthylamine-7-sulfonic acid) in 30 min on a Cjg column (A = 254 nm). Baseline resolution was achieved using an aqueous 10 mM phsophate buffer pH 6.8 mobile phase. The capacity ctors for these and 10 additional compounds belonging to these classes of compounds were tabulated. 

Llthol Reds. Lithol Red or Pigment Red 49 1/7103-38-4] is one of the most important of the precipitated salt pigments. They comprise a family of sodium (PR 49), barium (PR 49 1), calcium (PR 49 2), and strontium (PR 49 3) salts of dia2oti2ed Tobias acid or 2-naphthylamine-l-sulfonic acid coupled with 2-naphthol. The most popular are the barium and calcium salts, the former being yellower in shade. These reds are used where brightness, bleed resistance, and low cost ate of primary importance. They are neither resistant to heat nor chemicals, and are used primarily in printing inks and some inexpensive air-dried industrial paints where good durabiUty is not requited. 

The best source of information on preparative aspects of coupling reactions is still the book of Fierz and Blangey (1952). Four examples of coupling reactions can be found in Organic Syntheses (Conant et al., 1941, and Fieser, 1943 Azo coupling with 1- and 2-naphthol Hartwell and Fieser, 1943 8-Hydroxy-l-naphthylamine-2,4-di-sulfonic acid Clarke and Kirner, 1941 A/,7V-Dimethylaniline). 

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