1-Naphthol solution

For use, add 270 mL of solution (2) to 30 mL of solution (1). Rosolic acid (indicator). Dissolve 1 g of rosolic acid (Cj,Hj Oj) in 10 mL of ethanol and add 100 mL of distilled water. Sakaguchi Reagent (for the presence of arginine in proteins or peptides). To 10 drops of the saturated protein or peptide solution, add 5 drops of 6 N NaOH followed by 5 drops of 0.05% (mass/mass) ethanolic 1-naphthol solution and 10 drops of... 

Reagents 3% alcoholic 1-naphthol solution cone, sulfuric acid. 

Procedure To a dilute aqueous monosaccharide solution (2 ml) 1-naphthol solution (five drops) is added, and then several milliliters of cone, sulfuric acid are added carefully down the sides of the test tube. A violet or red color is formed on the surface of the sulfuric acid. After mixing, the liquid assumes a dark violet color and after dilution a blue-violet precipitate separates which is soluble in ether with a yellow color. A control experiment is carried out simultaneously without 1-naphthol, as a series of substances gives similar colors with sulfuric acid alone. 

Dissolve 4 5 ml. of aniline in a mixture of 10 ml. of concentrated hydrochloric acid and 20 ml. of water cool the solution to 5°, and diazotise by the addition of 4 g. of sodium nitrite dissolved in 20 ml, of water, observing the usual precautions given on page 181. Dissolve 7 g. of 2-naphthol in 60 ml. of 10% sodium hydroxide solution contained in a 200 ml. beaker, and cool this solution to 5 by external cooling, aided by the direct addition of about 20-30 g. of crushed ice. Now add the diazotised solution very slowly to the naphthol solution, keeping the latter well stirred meanwhile the mixed solutions immediately develop a deep red colour, and the benzeneazonaphthol should... 

A) Diazotizalion of Sulfanilic Acid.—A mixture of 105 g. (0.5 mole) of sulfanilic acid dihydrate, 26.5 g. (0.25 mole) of anhydrous sodium carbonate, and 500 cc. of water is heated and stirred until all the sulfanilic acid has dissolved, and the solution is then cooled in an ice bath to 15° (sodium sulfanilate begins to crystallize at this temperature). A solution of 37 g. (0.54 mole) of sodium nitrite in 100 cc. of water is added and the resulting solution is poured at once onto a mixture of 106 cc. (1.25 moles) (Note i) of concentrated hydrochloric acid (sp. gr. 1.18) and 600 g. of ice contained in a 2-I. beaker. The solution, from which -benzenediazonium sulfonate separates on stirring, is allowed to stand in an ice bath for fifteen to twenty-five minutes, during which time the naphtholate solution is prepared. 

Dime thoxyaniUne Apply sample solution as spots then apply diazonium chloride and a-naphthol solution and develop after 2 min. [61]... 

Nitrosylsulfuric acid, prepared by dissolving sodium nitrite in concentrated sulfuric acid, is employed for amines of low basicity, whose diazonium salts will hydrolyze in dilute acid. In order to synthesize Pigment Orange 5, for instance, 2,4-dinitroaniline is dissolved in concentrated sulfuric acid and diazotized preferably with nitrosylsulfuric acid. Coupling is carried out with a (3-naphthol suspension, produced by acidifying a sodium naphtholate solution. 

The sample is first dissolved in 2 M hydrochloric acid, and then 1 drop of this solution is placed on a white tile. One then adds 1 drop of a 1% sodium nitrite solution and 1 drop of a 4% 2-naphthol solution in 2M sodium hydroxide, and observes a red-orange color as a positive reaction. 

The melting point of the />-toluenesulfonylanthranilic acid is not a good criterion of purity because the />-toluenesulfonic acid salt of anthranilic acid has about the same value. The neutral equivalents are widely different 154 for the salt and 291 for p-toluenesulfonylanthranilic acid. The compound obtained in this preparation gives a negative test for anthranilic acid on diazotization and treatment with alkaline /3-naphthol solution. The probable impurity is the sodium salt of -toluene-sulfonylanthranilic acid. 

Sugar is detected in these waters by treating 2 c.c. of the liquid with 5 drops of 20% alcoholic a-naphthol solution and then carefully adding 10 c.c. of concentrated sulphuric acid (absolutely free from nitric acid) so that the two liquids do not mix. In presence of sugar, a violet ring forms at the surface of separation. A few comparative tests will indicate if the quantity of sugar is estimable the reaction is very sensitive and detects even o ooi% of sugar. 

When this ceases, the liquid is filtered and the filtrate, which should be acid, cooled to about 150 and treated with 5-10 drops of a 10% aqueous sodium nitrite solution the acid is neutralised with sodium carbonate, cooling meanwhile, and to the liquid, which is turbid owing to the presence of zinc carbonate, are added 1-2 drops of alkaline a-naphthol solution (01 gram a-naphthol, 100 c.c. water, 5 c.c. of caustic soda solution of sp. gr. 1 35). If the spirit contains benzene or its homologucs, an orange-red coloration is produced in consequence of the formation of an azo-colouring matter from the a-naphthol and the diazo-compound of the aniline or analogous base. 

In supercritical fluids, the possibility of local composition enhancements of cosolvent about a solute suggests that we should see enhancement of anion fluorescence if the water cosolvent clusters effectively about the 2-naphthol solute. Although in liquids the water concentration must be >30% to see anion emission, the higher diffusivity and density fluctuations in SCFs could allow stabilization of the anion at much lower water concentrations provided that the water molecules provide sufficient structure. Therefore the purpose of these experiments was to investigate 2-naphthol fluorescence in supercritical CO 2 with water cosolvent in the highly compressible region of the mixture to probe the local environment about the solute. 

Diazotizadon and coupling A 1% sodium nitrite solution (in I M hydrochloric acid) is sprayed on the plate, followed by a 0.2% a-naphthol solution in 1 M potassium hydroxide and drying. 

Nitroso-naphthol solution. Spray the plate with the reagent, then spray with a 10% v/v solution of hydrochloric acid and heat at 110° for 20 minutes. Blue-black spots on a yellow background are given by ergot alkaloids. 

Naphthol. On passing dichloroethyl sulphide vapours through an alcoholic and strongly alkaline solution of /3 naphthol, a turbidity is produced which slowly settles. The naphthol solution is prepared by adding Too ml. N/50 sodium hydroxide solution to I ml. of a 10% alcoholic solution of ]8 naphthol. As this mixture turns brown on keeping, the two solutions should not be mixed until just before using. 

To a solution containing not more than 30 pg of Co, add 1 ml of the 1-nitroso-2-naphthol (or 2-nitroso-l-naphthol) solution with stirring, adjust the pH of the solution with ammonia to 4 (or 5 in the case of 2-nitroso-l-naphthol), and allow to stand for 30 min. Transfer the solution to a separating funnel and extract with two portions of CHCI3. Shake the combined extracts with 2 M HCl, followed by two portions of 2 M NaOH, and finally wash with water. Transfer the extract to a 25-ml standard flask, make up to the mark with chloroform, and measure the absorbance of the solution at 415 nm (in the case of 2-nitroso-l-naphthol, at 365 nm), using the solvent as the reference. 

Apply bands of sample solution, spray with sodium nitrite in 1 mol/1 hydrochloric acid solution and heat to 105 °C for 5 min. After cooling apply -5% a-naphthol solution and dry in-a stream of—... 

Cautiously and slowly add the cold diazonium salt solution to the P-naphthol solution with vigorous constant stirring. Special care must be taken for not allowing the temperature of the reaction mixture rise beyond 5°C. If need be, crushed ice should be added in between while the coupling-reaction proceeds. 

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