CHEMISTRY  , ORGANIC) . a-Nilronaphthalene, C16H7•NO2, is formed by the

direct nitration of naphthalene . For its commercial preparation see O . Witt, Die chemische Industrie, 1887, lo, p . 215 . It crystallizes in yellow needles, which melt at 61° C., and are readily soluble in alcohol . By the action of nitro-sulphuric acid it is converted into a mixture of 1.5 and 1.8 dinitronaphthalenes (P . Friedlander, Be?'" 1899, 32, p . 3531) . When heated with aniline and its salts it yields phenylrosindulin (German patent 67339 (1888)) . 13-Nilronaphthalene is prepared by acting with ethyl nitrite on an alcoholic solution of 2-nitro-a-naphthylamine in the presence of sulphuric acid (E . Lellmann and A .

Remy, Ber., 1886, 19, p . 237), or with freshly prepared

potassium cupronitrite on A-naphthalene diazonium sulphate (A . Hantzsch, Ber., 1900, 33, p . 2553) . It crystallizes in small yellow needles which melt at 78° C. and are volatile in steam . Sulphonic Acids.—Two monosulphonic acids (a and ,e) result by acting with sulphuric acid on the hydrocarbon, the a-acid pre-dominating at low temperatures (8o° C. and under) and the 0-acid at higher temperatures (170°-200° C.) . They are crystalline, hygroscopic compounds and are employed for the manufacture of the naphthols . Numerous di- and tri-sulphonic acids are known . a-Naphthoquinone, C10H602, resembles benzoquinone, and is formed by the oxidation of many a-derivatives of naphthalene with chromic acid . It crystallizes in yellow needles which melt at 125° C . It sublimes readily, is volatile in steam and reduces to the corresponding dihydroxynaphthalene . R Naphthoquinone is formed by oxidizing 2-amino-a-naphthol (from /3-naphthol-orange by reduction) with ferric chloride .

It crystallizes in red needles, which melt at 115° C; it has no

smell and is non-volatile (cf. phenanthrenequinone).Alizarin black,C10H4(OH)202•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 peroxide . a-Naphthoic acid, C1oH7•CO2H, is formed by hydrolysis of the nitrile, obtained by distilling potassiuma-naphthalene sulphonate with potassium cyanide (V . Merz, Zeit. f . Chemie, 1868, p . 34), or by heating the sulphonate with sodium formate (V . Meyer, Ann.,187o, 156, p . 274) . It forms needles which melt at 16o° C . /3-Naphthoic acid, obtained by boiling ,B-methylnaphthalene with dilute nitric acid, or by hydrolysis of its nitrile (formed when formyl-/3-naphthalide is heated with zinc dust), crystallizes from alcohol in needles which melt at 184° C .