Zincke found that the products obtained by coupling a diazonium salt with a-naphthol, and by condensing phenylhydrazine with a-naphthoquinone, were identical; whilst Meldola acetylated the azophenols, and split the acetyl products by reduction in acid solution, but obtained no satisfactory results.
A-Naphthoquinone, C10H602, resembles benzoquinone, and is formed by the oxidation of many a-derivatives of naphthalene with chromic acid.
(-Naphthoquinone is formed by oxidizing 2amino-a-naphthol (from 0-naphthol-orange by reduction) with ferric chloride.
Phenanthrenequinone).Alizarin black,C l oH 4 (OH) 2 0 2 NaHS03, the sodium bisulphite compound of 7.8 dioxy-anaphthoquinone, is a dyestuff used for printing on cotton in the presence of a chromium mordant The naphthoquinone is prepared by the action of zinc and concentrated sulphuric acid on a-dinitronaphthalene.
A 2.6 naphthoquinone results on oxidizing 2.6 dihydroxynaphthalene with lead Or Hydroxynaphthalenes, C 1 oH 7 OH, the naphthalene homologues of the phenols.
It forms needles which melt at 160° C. (3-Naphthoic acid, obtained b y boiling 0-methylnaphthalene with dilute nitric acid, or by hydrolysis of its nitrile (formed when formyl-0-naphthalide is heated with zinc dust), crystallizes from alcohol in needles which Nitrosonaplithols or naphthoquinone-oxames, C 1 oH 6 (OH)(NO) or melt at 184° C. C 1 oH 6 (: NOH): 0.
Two are known, namely 4-nitroso-a-naphthol or 13; a-naphthoquinone-oxime, formed by the action of nitrous acid on a-naphthol or of hydroxylamine hydrochloride on a-naphthoquinone (H.
Schmidt, Ber., 1884, 17 p. 2064); and 2-nitrouo-a-naphthol (, -naphthoquinone-oxime), formed by the action of hydroxylamine hydrochloride on 13-naphthoquinone.