2-naphthalene sulfonic acid, 8-Hydroxy

Amino-3-hydroxy-7-nitro-l-naphthalene-sulfonic acid [6259-63-8]... 

Heterocycles are known to have O—S, S—N, and O—N bonds. The cyclization of peri-hydroxy and peri-amino-substituted naphthalene sulfonic acids gives rise to 1,8-naphthosultone 246 and 1,8-naphthosultam 247, respectively (33MI2 63MI1). On gas phase photolysis of naphtho[/>c]-... 

Disodium 6-Hydroxy-5-[(2-methoxy-5-methyl-4-sulfophenyl) azo]-8-(2-methoxy-5-methyl-4-sulfophenoxy)-2-naphthalene-sulfonic Acid Not more than 1.0%. 

Naphthol Yellow S (citronin A, flavianic acid sodium salt, 8-hydroxy-5,7-dinitro-2-naphthalene sulfonic acid disodium salt) [846-70-8] M 358.2, m dec on heating. Greenish yellow powder soluble in H2O. The free sulfonic acid can be recrystd from dil HCl (m 150°) or AcOH-EtOAc (m 148-149.5°). The disodium salt is then obtained by dissolving the acid in two equivalents of aqueous NaOH... 

The site at which the sulfo group appears in / -naphthol depends very markedly on the temperature. At low temperatures 2-hydroxy-1-naphthalene-sulfonic acid is obtained 150 at higher temperatures or when an excess of sulfuric acid is used, migration of the sulfo group leads to 7-hydroxy- 1-naph-thalenesulfonic acid (croceic acid), and finally at 110° almost exclusively to 7-hydroxy-2-naphthalenesulfonic acid (Schaffer acid). Further treatment with an excess of sulfuric acid leads to / -naphthol-di- and -tri-sulfonic acids, which are important for the dyestuffs industry but which will not be discussed in detail... 

Acid red 14 [4-hydroxy-3,4-azodi-l-naphthalene-sulfonic acid disodium salt disodium 2-(4-sulfo-1 -naphthyl-azo)-1 -naphthol-4-sulfonate, chromotrope FB, azorubin. Cl 14720] [3567-69-9]... 

CAS 1658-56-6 EINECS/ELINCS 216-760-3 Synonyms Cl 15620 Ext. D C Red. no. 8 Fast red A 4-(2-Hydroxynaphthalen-1-ylazo) naphthalene-1-sulfonic acid, sodium salt 4-((2-Hydroxy-1 -naphthalenyl) azo)-1 -naphthalene sulfonic acid sodium salt 1-Naphthalenesulfonic acid, 4-((2-hydroxy-1-naphthalenyl) azo)-, monosodium salt Red no. 506 Rocceline Roccelline Solid red A Classification Azobenzene Empiricai C2oHi4N2Na04S Properties M.w. 401.41 m.p. 280 C Toxicoiogy Mutagen TSCA listed Storage Store in cool, dry place keep container closed when not in use... 

Hydroxynaphthalen-1 -ylazo) naphthalene-1 -sulfonic acid, sodium salt 4-((2-Hydroxy-1-naphthalenyl) azo)-1-naphthalene sulfonic acid... 

Mahmoud, M.E. Soayed, A.A. Hafez, O J. Selective sohd phase extraction and pre-concentration of heavy metals from seawater by physicahy and chemicahy immobilized 4-amino-3-hydroxy-2-(2-chlorobenzene)-azo-l-naphthalene sulfonic acid silica gel. Microchim. Acta 2003,143 (1), 165. 

In our laboratory, this method was appUed to the purification of food mono-azo dyes. Amaranth, New Coccine, and Sunset Yellow FCF were purified at 99.7%, 99.5%, and 99.3%, respectively, from 1-23 g of commercial dyes. Continued research has led to the purification of impurities present in commercial Sunset Yellow FCF that include RS-SA (trisodium salt of 3-hydroxy-4-[sulfophenyl] azo-2,7-naphthalene disulfonic acid), GS-S A (1 -[4-sulfophenyl]azo)-2-naphthol-6,8-disulfonic acid), DONS (disodium salt of 6,6 -oxybis-2-naphthalene sulfonic acid), and 2N-SA (sodium salt of 4-[(2-hydroxy-l-naphthalenyl)azo]benzenesulfonic add). The method successfully isolated GS-SA from Sunset Yellow FCF. " ... 

Arsonophenyl)azo]-6- (5-chloro-2-hydroxy-3-sulfophenyI)azol-4,5-dihydroxy-2,7-naphthalene sulfonic acid, 8CI... 

Eriochrome Blue Black R (Palatine Chrome Black 6BN, Calcon, 3-hydroxy-4-(2-hydroxy-l-naphthylazo)naphthalene-l-sulfonic acid Na salt] [2538-85-4] M 416.4, pK2 7.0, pKj 13,5. Freed from metallic impurities by three pptns from aqueous soln by addn of HCl. The ppted dye was dried at 60° under vacuum. Indicator for complexometry of Al, Fe and 7i. 

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