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CHEMISTRY

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Originally appearing in Volume V19, Page 168 of the 1911 Encyclopedia Britannica.
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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.
End of Article: CHEMISTRY
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