Nitroso-P-naphthol

Treatment of a solution of sodium nitrite and the sodium salt of (3-naphthol with sulphuric acid gives an excellent yield of a-nitroso- p-naphthol  

Dissolve 100 g. of (3-naphthol (Section IV,102) in a warm solution of 28 g. of sodium hydroxide in 1200 ml. of water contained in a 2-5 litre round-bottomed or bolt-head flask fitted with a mechanical stirrer. Cool the solution to 0° in a bath of ice and salt, and add 50 g. of powdered sodium nitrite. Start the stirrer and add, by means of a separatory funnel supported above the flask, 220 g. (166-5 ml.) of sulphuric acid (sp. gr. 1-32) at such a rate that the whole is added during 90 minutes 

If a-nitroso-(3-naphthol is required in the crystalline condition, recrystallise it from light petroleum, b.p. 60-80° (7-5 ml. per gram) the recovery is almost quantitative, m.p. 106°. 

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Acetylene compounds Dicobaltoctacarbonyl Formation of colored complexes. After the reagent excess has been washed out, reaction with bromine vapor yields cobalt bromide, which reacts with a-nitroso-P-naphthol to yield red chromatogram zones on an almost colorless background. [11]... 

Methylphenylnitrosoamine E thylpheny Ln itrosoamine Nitrosobenzene o-Nitrosotoluene. m-Nitrosotoluene. p-Nitrosotoluene. a-Nitrosonaphthalene. p-Nitrosophenol. a-Nitroso-P-naphthol. 4-Nitroso- a-naphthol pNitrosoNNdimethylaniline p-Nitroso -NN diethylani line. p-Nitroso-N-methylaniline p-Nitroso-Nethylaniline p-Nitrosodiphenylamine... 

Gravimetric Methods.—The main difficulty is to obtain the cobalt in the form of one of its compounds entirely free from nickel or other metal. This may be accomplished by the cyanide method described under Wet Tests above. The solution, after separation of the nickel, is evaporated with dilute sulphuric acid until white fumes are evolved. On addition of water a solution of cobalt sulphate results, and the cobalt may be precipitated in a variety of ways, for example as oxide with hypobromites or persulphates,2 as sulphide, as cobalti-nitroso p-naphthol, or as basic carbonate.3 In each case the precipitate is ignited and reduced to metallic cobalt in a current of pure hydrogen. 

Since ot-nitroso-p-naphthol (11 pK = 7.70) and p-nitroso-a-naphthol (p/C 7.22) are weaker acids than nitrosophenylhydroxylamine (16 p/C=4.15), complex formation and solvent extraction require more alkaline solutions. Tris complexes of Fe or Co are formally uncharged octahedral species extractable into light petroleum like the uncharged square planar complex of Pd . On the other hand the bis complexes of Fe , Ni and Co require two water molecules to complete their coordination sphere and though extractable into diethyl ether are insoluble in the non-polar ligroin. 

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