Naphthol blue

Naf tol, n. naphthol. -artikel, m. (Dyeing) naphthol style, -at, n. naphtholate. -blsu, n. naphthol blue, -gelb, n. naphthol yellow, -griin, n. naphthol green. 

Reactive Black 5, Naphthol Blue Black, Chicago Sky Blue ... 

Dibasic calcium phosphate 0.2 g Hydroxy naphthol blue Each ml of 0.05 M disodium edetate = 0.002004 g of Ca... 

Amido black 10B stain 0.1% (w/v) amido black (naphthol blue black 10B, Sigma) in 10% (v/v) acetic acid 5% (v/v) acetic acid Plastic boxes... 

Azo acid blue, azo cyanme, azo merino blue, azo navy blue, brilliant cloth blue, chromazone blue,dommgo blue black, eno fast brilliant blue, ethyl acid blue, cresol blue black, lanacyl blue, naphthol blue black, naphthylamme blue black, " orthocyanme, phenyl blue black, sulphon acid blue, tolyl blue S B, S R, S T... 

The USP [2] recommends a titrimetric method for the determination of EDTA using chelometric standard calcium carbonate previously dried at 110°C for 2 hours, and hydroxy naphthol blue as the indicator. The weight of EDTA (in mg) is calculated by the formula ... 

Nasr, C. Vinodgopal, K. Hotchandani, S. Kamat, P. V. Excited state and reduced forms of a textile diazo dye, Naphthol blue black. Spectral characterization using laser flash photolysis and pulse radiolysis. Radiat. Phys. Chem. 1997, 49, 159. 

Luo, J. and Hepel, M. (2001). Photoelectrochemical degradation of naphthol blue black diazo dye on WO3 film electrode. Electrochim. Acta 46(19), 2913-2922. 

Assay Dissolve about 300 mg of sample, accurately weighed, in 150 mL of water containing 2 mL of 2.7 N hydrochloric acid. While stirring, preferably with a magnetic stirrer, add about 30 mL of 0.05 M disodium EDTA from a 50-mL buret, then add 15 mL of 1 A sodium hydroxide and 300 mg of hydroxy naphthol blue indicator, and continue the titration to a blue endpoint. Each milliliter of 0.05 M disodium EDTA is equivalent to 7.909 mg of Ca(C2H302)2. 

Hydroxy Naphthol Blue The disodium salt of l-(2-naph-tholazo-3,6-disulfonic acid)-2-naphthol-4-sulfonic acid deposited on crystals of sodium chloride. Small blue crystals, freely soluble in water. In the pH range between 12 and 13, its solution is red-pink in the presence of calcium ion and deep blue in the presence of excess disodium EDTA. 

It should be mentioned in passing that the first oxazine to attain technical importance was Meldola blue (naphthol blue, Bengal blue), prepared from nitrosodimethylaniline hydrochloride and naphthol. It is a very fast dye but does not give pure shades. Furthermore, its dust irritates the mucuous membranes so severely that many persons cannot work with it. Despite these disadvantages, however, Meldola blue is still rather widely used. 

The monoazo dye is not isolated. An excess of diazotized aniline has a deleterious effect. The naphthol blue-black B is salted out at 90°C. with 15 per cent salt to yield a lustrous, bronzy product. This dye, on reduction with Na2S at 25°, yields a valuable dark green azo dye, azo dark green, having the structure ... 

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