1,8-Dihydroxynaphthalene- 3,6-disulfonic

Dihydroxynaphthalene-3,6-disulfonic acid (chromotropic acid) (Other values on Vol.3, p.235)... 

Juglone is most readily synthesized by Bemthsen s method. However, this method is too drastic and results in low yields (56). Somewhat better yields are obtained by using Fremy s salt (potassium nitroso disulfonate) as the oxidant (57). By using thallium trinitrate to oxidize 1,5-dihydroxynaphthalene, yields as high as 70% of juglone have been reported (58). 

Unique methods based on new principles have been developed within the past 10 years. Threonine (27,28,249) is oxidized by lead tetraacetate or periodic acid to acetaldehyde, which is determined by photometric analysis of its p-hydroxydiphenyl complex or iodometric titration of its combined bisulfite. Serine is oxidized similarly to formaldehyde, which is determined gravimetrically (207) as its dimedon (5,5-dimethyldihydro-resorcinol) derivative or photometric analysis (31) of the complex formed with Eegriwe s reagent (l,8-dihydroxynaphthalene-3,5-disulfonic acid). It appears that the data obtained for threonine and serine in various proteins by these oxidation procedures are reasonably accurate. [Block and Bolling (26) have given data on the threonine and serine content of various proteins. ]... 

The rate constants in Figure 5-3 were measured by injecting the solution of the (E)-diazoate into a buffer solution that also contained a highly reactive coupling component (2-naphthol-3,6-disulfonic acid, except at pH values below 2.5, where l,8-dihydroxynaphthalene-3,6-disulfonic acid was used instead). The diazonium ion formed reacts rapidly with these naphthols, and the concentration of the corresponding azo compounds was determined spectrophotometrically. 

The core scaffold of three of the previously identified inhibitors, VI, SI, and S5 (31), is 4,5-dihydroxynaphthalene-2,7-disulfonate—structure A in Durrant et al. (47). Similarity searches were performed using three structures similar to this core scaffold naphthalene-2-sulfonic acid, 2-naphthoic acid, and 2-nitronaphthalene—structures B, C, and D in Fig. 1 of Durrant et al. (47), respectively. 

Figure 4. Polarograms for lmF manganese(II) perchlorate in a solution that contains 0.1F 4,5-dihydroxynaphthalene 2,7-disulfonate and...

Technical Observations. The dyes described above have largely replaced the analogous dyes from chromotropic acid (l,8-dihydroxynaphthalene-3,6-disulfonic acid). They are cheaper and more stable to light. 

Dihydroxynaphthalenemono- and disulfonic acids couple so rapidly, even the second time, that the coupling is carried out in acetic acid solution containing sodium acetate, using diazotized p-aminoacetanilide. With many of the acids, the coupling requires several hours, as, for example, with chromotropic acid (l,8-dihydroxynaphthalene-3,6-di-sulfonic acid). In this case, also, the dye is highly soluble and separates slowly from the unreacted chromotropic acid so that considerable care must be exercised. 

The reaction of di- and polysulfonic acids can usually be carried out so that the replacement of the sulfo groups by hydroxyls takes place stepwise (partial alkali fusion). Thus, phenol-m-sulfonic acid is obtained from benzene-m-disulfonic acid under mild conditions, while resorcinol is formed under more vigorous conditions (see page 144) similarly, naphthalene-l,5-disulfonie acid yields, first, l-naphthol-5-sulfonic acid, then l,5 dihydroxynaphthalene, both valuable azo dye... 

Intorre and Martell (237) have also studied the formation of mixed chelate species in which the zirconium 1 1 complex with the hexa-dentate chelating ligands, ethylenediaminetetraacetic acid, iV-hydroxy-ethylethylenediaminetriacetic acid, and m7 s-cyclohexanediaminetetra-acetic acid, are shown to take up one mole of the bidentate ligands, l,2-dihydroxybenzene-3,5-disulfonate l,8-dihydroxynaphthalene-3,6-disulfonate 8-hydroxyquinoline-5-sulfonate, and acetylacetone (except ZrHEDTA), to form 8-coordinate 1 1 1 species. At least for the zir-conium-EDTA-l,2-dihydroxybenzene-3,5-disulfonate species, there is evidence for dimerization (230). Additionally, the Zr EDTA complex reacts with one mole of the bidentate ligands, 5-sulfosalicyclic acid, alizarin sulfonate, citric acid, and lactic acid to form 1 1 1 complexes tartaric acid and pyrophosphate ions form complexes which could not be identified. The zirconium-nitriloacetic acid complex in the presence of two moles of oxalic acid or l,2-dihydroxybenzene-3,5-sulfonate also forms 1 1 1 complexes in solution. 

Chromotropic acid (l,8-dihydroxynaphthalene-3,6-disulfonate) reacts with zirconium(IV) to form a 1 1 complex. The apparent equilibrium constant for this system at pH 2.0 and at a metal ion concentration of 5 X 10 M n 0. M KCl, was calculated to be logAzr = 3.63 (466). The initial report (98) of little or no reaction appears to be incorrect. A nitroso derivative of this ligand reacts with zirconium(IV) to give a red-violet precipitate in weak acid solution (535). 

Bis(carboxymethyl)aminomethyl-l,8-dihydroxynaphthalene-3,6- 70EM disulfonic acid (C H O S )... 

The most commonly employed broad-spectrum PCR reagents are 4-(2-pyridylazo)resorcinol (PAR) and 2,7-bis(2-arsonophenylazo)-l,8-dihydroxynaphthalene-3,6-disulfonic acid (arsenazo III). The structures of these compounds are shown in Fig. 7. In general use, PAR is the preferred reagent for the PCR detection of transition metal ions, whereas arsenazo 111 is preferred for lanthanide ions. 

Phenyl-2,3-dimethyl-4-dimethylamino-l,2-diazol-5-one (pyramidone) 3,6-Bis(4-antipyrylazo)-4,5-dihydroxynaphthalene-2,7-disulfonic acid 2. 1,3-Diazoles ... 

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