It is a colourless solid, which melts at 80° C., and boils at

218° C. It crystallizes in the mono clinic system; it is to be noted that a- and B-naphthol assume almost identical forms, so that these three compounds have been called isomorphous. It is insoluble in water, but is readily soluble in alcohol, and ether. It has a characteristic smell, and is very volatile, distilling readilyinacurrent of steam. It acts as aweak antiseptic. It is used for enriching coal gas, as a vermin killer, in the manufacture of certain azo dyes, and in the preparation of phthalic acid (q.v.). When passed through a red-hot tube packed with carbon it yields BB-dinaphthyl, (C10H7)2. It formsacrystalline compound with picric acid. It readily forms addition products with chlorine and with hydrogen; the dichloride, C10HgCl2, is obtained as a yellow liquid by acting with hydrochloric acid and potassium chlorate; the solid tetrachloride, C10 Hg Ch, results when chlorine is passed into naphthalene dissolved in chloroform. Numerous hydrides are known; heated with red phosphorus and hydriodic acid the hydrocarbon yields mixtures of hydrides of composition Cml-110 to CIOHQO. - Sodium in boiling ethyl alcohol gives the a-dihydride, C10H10 (E. Bamberger, Bef., 1887, 20, p. 1705); and with boiling amyl alcohol the B-tetra hydride, CNH12 (E. Bamberger, Bef., 1890, 23, p. 1561). The a.-tetra hydro naphthalene is formed when naphthalene is heated with phosphonium iodide at I7O°-190° (A. v. Baeyer). Structurally naphthalene may be represented as a fusion of two benzene nuclei, the hydrogen atoms being numbered as in the inset S 1

formula 1, 4, 5, 8 are a-positions, 2, 3, 6, 7 are /3; 5 4

1-5 or 4-8 diderivatives are ana, whilst 1-8 or 4-5 are peri (see CHEMISTRY, ORGAN1c).

a-Nilronaphthalene, CNH1-NO2, is formed by the direct nitration of naphthalene. For its commercial preparation see O. Witt, Die chemische Industrie, 1887, 10, p. 215. It crystallizes in yellow needles, which melt at 61° C., and are readily soluble in alcohol. By the action of nitro-sul huric acid it is converted into a mixture of 1-5 and 1-8 dinitronaplithalenes (P. Friedlander, Bef., 1829, 32, p. 3531). V/hen heated with aniline and its salts it yieldsp enylrosindulin (German patent 67339 (1888)). 6-Nitronaphthalene 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, Bef., 1886, 19, p. 237), or with freshly prepared potassium cupronitrite on B-naphthalene diazonium sulphate (A. Hantzsch, Bef., 1900, 33, p. 2553). It crystallizes in small yellow needles which melt at 78° C. and are volatile in steam. Sulphonie Acids.-Two monosulphonic acids (a and B) result by acting with sulphuric acid on the hydrocarbon, the a-acid predominating at low temperatures (8o° C. and under) and the B-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.-Naphthoguinone, Cr0H, ,O2, resembles benzoquinone, and is formed by the oxidation of many a-derivatives of naphthalene with chromic THOLS

NAPHTHOLS, or HYDROXYNAPHTHALENES, C10H1OH, the naphthalene homologies of the phenols. The hydroxyl group is more reactive than in the phenols, the naphthols being converted into naphthylamines by the action of ammonia, and forming ethers and esters much more readily. a-Naphthol may be prepared by fusing sodium-a-naphthalene sulphonate with 'caustic soda; by heating a.-naphthylamine ~ sulphate with water to 200° C. (English Patent 14301 (1892)); and by heating phenyl isocrotonic acid (R. Fittig and H. Erdmann, Ann. 1885, 227, p. 242): C6H5CH:CH-CHQ-COQH =C10H7OH-l-HZO. It forms colourless needles which melt at 94° C.; and is readily soluble in alcohol, ether, chloroform, and caustic alkalis. A It is volatile in steam. With ferric chloride it gives a dark-blue precipitate of a-dinaphthol, HO~C10H6-C10H6~OH. Alkaline potassium permanganate oxidizes it to phenyl-glyoxyl-ortho-carboxylic acid, HO2C-C6H4~CO-CO2H. It is reduced by sodium in boiling amyl alcohol solution to “ aromatic ” tetra hydro-a-naphthol (reduction occurring in the ring which does not contain the hydroxyl group). When heated with hydrazine hydrate at I6O° C. it gives a-naphthyl hydrazine, C10H7NH-NH2 (L. Hoffmann, Bef., 1898, 31, p. 2909). Nitric acid converts it into nitro-compounds, which are occasionally used for dyeing silk and wool.

Martins yellow, C,0H5(NO2)2ONa-HZO, the sodium salt of 2-4 dinitro-a-naphthol (for notation see NAPHTHALENE), is prepared by the action of nitric acid on a-naphthol-2-4-disulphonic acid. It forms orange-yellow lates and dyes wool a golden yellow (from an acid bath). Naphtholyellow S., CwH4(ONa) (NO2)2503Na, prepared by the action of nitric acid on a-naphthol-2-4-7-trisulphonic acid, is an orange-yellow powder which dyes wool and silk yellow (from an acid bath).

Numerous mono-, di- and trisulphonic acids of a-naphthol are employed in the preparation of azo dyes. The most important is Nevile and Wint er's acid, CwH¢, (OH)(SO3H)(1-4), formed when diazotized naphthionic acid (a-naphthylamine-4-sulphonic acid) is boiled with dilute sulphuric acid (Nevile and Winther, Ber.,1880, 13, p. 1949), or when sodium naphthionate is heated with concentrated caustic soda solution under pressure at 240°-260° C. (German patent 46307 (1888)). It melts at 170° C., and is readily soluble in water. With ferric chloride it gives a blue coloration. B-Naphthol, C,0H7OH, prepared by fusing' sodium 5-naphthalene sulphonate with caustic soda, crystallizes in plates which melt at 122° C. With ferric chloride it gives a green colouration, and after a time a White flocculent precipitate of a dinaphthol. With sodium in boiling amyl alcohol solution it gives a mixture of alicyclic and aromatic tetra hydro-5-naphthols (E. Bamberger, Bef., 1890, 23, p. 197). When heated with ammonium formate to 150° C. it forms B-naphthylamine. With nitrosodimethylaniline hydrochloride it forms M eldola's Blue (dimethylaminonaphthophenoxazonium chloride), C18H15N2OCl (R. Meldola,

Ber., 1879, 12, p. 2065).

The 73-naphthol sulphonic acids End extensive application in the colour industry. The most important members are shown in the acid. It crystallizes in yellow needles which melt at 125° C. It table:- sublimes readily, is volatile in steam and reduces to . .

th? C0ff@§ P0f1d1f1§ dhYdf°?<YH?Phllhal€§ 1C- H Nf1Phlh0'

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FORMULA. METHOD or PREPARATION. REMARKS. quznzme IS formed by oxidizing 2-amino-at-naphtliol (f'0m5'f1aPhfh0l'0f2§ f1g€bYfCdUCf10Ul}'V1thf0ff1C 01110; 2-oxy-8-sulphonic From B-naphthol and concen- Sodium salt soluble in Ylde; It C1'YSt3llZ@S IH F@Cl H€'<3dl€Sf which melt at l 15 (Baeyer's acid) trated sulphuric acid at strong alcohol. C; it has no smell and is non-volatile (cf. phenan- 50° 60° C threnequinone)./llizarinblack, C10H4(OH)2O2~NaHSO3, 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-Naphlhoic acid, CwH1-COQH, is formed by hydrolysis of the nitrile, obtained by distilling potassium-naphthalene sulphonate with potassium cyanide (V.

Merz, Zeit. f. Chemie, 1868, p. 34), or by heating the sulphonate with sodiumformate (V. Meyer, Ann., 1870, 156, p. 274). It forms needles which melt at 160° C. B-Naphthoic acid, obtained by boiling,8-methyl naphthalene with dilute nitric acid, or by hydrolysis of its nitrile (formed when formyl-,8-naphthalide is heated with zinc dust), crystallizes from alcohol in melt at 184° C.

2-oxy-6-sulphonic

(Schaffer's acid)

From B-naphthol and concentrated

sulphuric at 100° C.

Sodium salt insoluble in

alcohol.

2-oxy-7-sulphonic By fusion of naphthalene 2-7- Very soluble in water (F-acid) disulphonic acid with caustic and alcohol. soda at 200°-250° C.

2-oxy-3-6-disul honic The sodium salts separ(R-acid)) Both R- and G-acid from B- ated by crystallizanaphthol and concentrated tion. R-salt insoluble

Q— —-l sulphuric acid at IOO°- in alcohol; G-salt 2-oxy-6- 8-disulphonic 1 IODC. soluble.

(G-acid) .

2-oxy-3-6-8-trisulphonic A

From B-naphthol and fuming

sulphuric acid at 140°-160°C.

Alkaline solutions show

green fluorescence.

needles which| Nitrosonaphthols or naphthoguinone-oximes, C101-l¢, (OH)(NO) Cor Cwl-l5(:NOH):O. Two are known, namely 4-nitroso-a-naphthol or