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NAPHTHOLS, or HYDROXYNAPHTHALENES, C1...

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Originally appearing in Volume V19, Page 168 of the 1911 Encyclopedia Britannica.
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NAPHTHOLS, or HYDROXYNAPHTHALENES, C10H70H , the See also:naphthalene homologues of the phenols. The hydroxyl See also:group is more reactive than in the phenols, the naphthols being converted into See also:naphthylamines by the See also:action of See also:ammonia, and forming See also:ethers and See also:esters much more readily. a-Naphthol may be prepared by fusing See also:sodium-a-naphthalene sulphonate with See also:caustic soda; by See also:heating a-naphthylamine sulphate with See also:water to 200° C. (See also:English Patent 14301 (1892)); and by heating phenyl isocrotonic See also:acid (R. See also:Fittig and H. See also:Erdmann, See also:Ann. 1885, 227, p. 242): C6H6CH:CH•See also:CH2•See also:CO2H = C1oH70H+H20. It forms colourless needles which melt at 94° C.; and is readily soluble in See also:alcohol, See also:ether, See also:chloroform, and caustic alkalis. It is volatile in See also:steam. With ferric chloride it gives a dark-See also:blue precipitate of a-dinaphthol, HO•C10Hs•CIOHs•OH. Alkaline See also:potassium permanganate oxidizes it to phenyl-glyoxyl-ortho-carboxylic acid, H02C•CsH4•CO• CO2H.

It is reduced by sodium in boiling amyl alcohol See also:

solution to " aromatic " tetrahydro-a-naphthol (reduction occurring in the See also:ring which does not contain the hydroxyl group). When heated with See also:hydrazine See also:hydrate at 16o° C. it gives a-naphthyl hydrazine, CIOH7NH•See also:NH2 (L. See also:Hoffmann, Ber., 1898, 31, P. 2909). Nitric acid converts it into nitro-compounds, which are occasion-ally used for See also:dyeing See also:silk and See also:wool. See also:Martius yellow, C1oH6(NO2)2ONa•H20, the sodium See also: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 See also:orange-yellow plates and dyes wool a See also:golden yellow (from an acid See also:bath). Naphthol yellow S., C1oH4(ONa)(NO2)2SO3Na, prepared by the action of nitric acid on a-naphthol-2.4.7-trisulphonic acid, is an orange-yellow See also: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 See also:azo dyes. The most important is Nevile and See also:Winther's acid, C10H6(OH)(SO3H)(1.4), formed when diazotized naphthionic acid (a-naphthylamine-4-sulphonic acid) is boiled with dilute sulphuric acid (Nevile and Winther, Ber., 188o, 13, p. 1949), or when sodium naphthionate is heated with concentrated caustic soda solution under pressure at 240°–260° C. (See also:German patent 46307 (1888)).

It melts at 17o° C., and is readily soluble in water. With ferric chloride it gives a blue coloration. (3-Naphthol, C10H2OH, prepared by fusing sodium (3-naphthalene sulphonate with caustic soda, crystallizes in plates which melt at 122° C. With ferric chloride it gives a See also:

green colouration, and after a See also:time a See also:white flocculent precipitate of a dinaphthol. With sodium in boiling amyl alcohol solution it gives a mixture of alicyclic and aromatic tetrahydro-(3-naphthols (E. See also:Bamberger, Ber., 1890, 23, p. 197). When heated with ammonium formate to 15o° C. it forms /3-naphthylamine. With nitrosodimethylaniline hydrochloride it forms Meldola's Blue (dimethylaminonaphthophenoxazonium chloride), C18H15N20C1 (R. Meldola, Ber., 1879, 12, p. 2065). The $-naphthol sulphonic acids find extensive application in the See also:colour See also:industry.

The most important members are shown in the table: or naphthoquinone-See also:

oximes, C1oH6(OH)(NO) or C1oHs(: NOH) : O.

End of Article: NAPHTHOLS, or HYDROXYNAPHTHALENES, C10H70H

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