Naphthionic acid 3-Naphthol

Certain dyes when appHed by the afterchrome method are oxidized prior to metal complex formation. Examples iaclude. Chromotrope EB [3567-69-9] (52) (Cl Acid Red 14 Cl 14720) (naphthionic acid — l-naphthol-4-sulfonic acid) ia which a hydroxyl group is iatroduced by oxidation at the... 

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...

Probtem 18.63 Synthesize from naphthalene and any other reagents (a) naphthionic acid (4-amino-l-naphthalenesulfonic acid), (b) 4-amino-l-naphthol, (c) 1,3-dinitronaphthalene, (d) 1,4-diaminonaphthalene, (e) 1,2-dinitronaphthalene. Do not repeat the synthesis of any compound. ... 

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). 

Bailey et al. (199) and Singh (200) used ion-exchange HPLC for the separation of amaranth from the intermediates naphthionic acid and R-salt, as well as the side reaction products 2-naph-thol-6-sulfonic acid sodium salt (Schaeffer s salt), 2-naphthol-6,8-disulfonic acid disodium salt (G-salt), and 2-naphthol-3,6,8-trisulfonic acid trisodium salt (NTSA). 

Naphthols and Naphtholsulfonic Acids as Coupling Components. This series includes two important acid dyes with very similar structures C.I. Acid Red 88 (see Section 3.9.3), derived from diazotized naphthionic acid and 2-naphthol, and C.I. Acid Red 13, 16045 [2302-96-7] (2), from naphthionic acid and Schaffer s acid. Both are all-purpose dyes which, because of their attractive red shades, are still in use today in many areas of textile dyeing and also for leather and paper dyes. Wool dyeings produced with these dyes exhibit moderate fastness levels. 

Naphthol-4-sulfonic acid from naphthionic acid.,.. . 182... 

Action of bisulfite on a nitro compound or on a quinone or quinonemo-noxime, in which the nitro and nitroso groups are simultaneously reduced to amino groups. Examples are the preparation of l-naphthylamine-2,4-disulfonic acid from o-nitronaphthalene and bisulfite (naphthionic acid as by-product), and the manufacture of l-amino-2-naphthol-4-sulfonic acid from nitroso- -naphthol and bisulfite (page 201). 

At present three monosulphonic acids have been obtained from a-naphthol, but the constitution of only one of these is knowTi with any degree of certainty. This is the aa-acid prepared by Nevile and "V inther, and studied more closely by Witt. It is obtained by decomposition of the diazo-compound of naphthionic acid with water, and from its method of formation is constituted according to the formula ... 

For the determination of small quantities of -naphthol Patterson and Lerrigo have used the red colour obtained on making a solution containing )3-naphthol, naphthionic acid and sodium nitrite alkaline. A convenient range, where the depth of colour is proportional to the amount of /5-naphthol present, is obtained between 1 and 5 p.p.m. of the substance ... 

Riegler s test. A test for nitrous acid using sodium naphthionate and (3-naphthol. 

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