Hinsberg, Ann., 1887, 2 37, p. 340); by the oxidation of an ortho-diamine in the presence of a-naphthol (0.
If s-naphthylamine and 0-naphthol be reduced, tetrahydro products are obtained in which the aminoor oxy-bearing half of the molecule becomes aliphatic in character.
If a-naphthylamine and a-naphthol be reduced, the hydrogen atoms attach themselves to the non-substituted half of the molecule, and the compounds so obtained resemble aminodiethylbenzene, C 6 H 3 NH 2 (C 2 H 5) 21 and oxydiethylbenzene, C 6 H 3.
It may also be prepared (in the form of its acetyl derivative) by heating a-naphthol with sodium acetate, ammonium chloride and acetic acid (A.
0-Naphthylamine is prepared by heating 13-naphthol with zinc chloride-ammonia to 200-210° (V.
Weith, Ber., 1880, 13, 1300); or in the form of its acetyl derivative by heating /3-naphthol with ammonium acetate to 270-280° C. It forms odourless, colourless plates which melt at 111-112° C. It gives no colour with ferric chloride.
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.
Heated with sulphur it forms benzoic acid and stilbene: 2C 7 H 6 0+S = C6HS000H+C6H5CHS, 2C 6 H 5 CHS =2S +C14H12 Its addition compound with hydrocyanic acid gives mandelic acid C 6 H 5 CH(OH) COOH on hydrolysis; when heated with sodium succinate and acetic anhydride, phenyl-iso-crotonic acid C 6 H 5 CH: CH CH 2 000H is produced, which on boiling is converted into a-naphthol C 10 H 7 0H.
As an example we may take the case of mixtures of naphthalene and 13-naphthol, substances which form solid solutions in each other.
We should expect to find supersolubility curves lying below the solubility curves, and this result has been realized experimentally for the supersolubility curves of mixtures of salol (phenyl salicylate) and betol (/3-naphthol salicylate) represented by the dotted lines of fig.
It is a colourless solid, which melts at 80° C., and boils at 218° C. It crystallizes in the monoclinic system; it is to be noted that aand 0-naphthol assume almost identical forms, so that these three compounds have been called isomorphous.
(-Naphthoquinone is formed by oxidizing 2amino-a-naphthol (from 0-naphthol-orange by reduction) with ferric chloride.
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.
It is reduced by sodium in boiling amyl alcohol solution to "aromatic" tetrahydro-a-naphthol (reduction occurring in the ring which does not contain the hydroxyl group).
Martius yellow, C10H5(N02)20Na H20, 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.
Naphthol yellow S., C10H4(ONa) (NO 2) 2 S0 3 Na, prepared by the action of nitric acid on a-naphthol - 2.4.
Numerous mono-, diand trisulphonic acids of a-naphthol are employed in the preparation of azo dyes.
0-Naphthol, C 1 oH 7 OH, prepared by fusing sodium 0-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.
The 0-naphthol sulphonic acids find extensive application in the colour industry.
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.
Knorre (Ber., 1885, 18, p. 169) separate the metals by adding nitros01 3-naphthol in the presence of 50% acetic acid, a precipitate of cobalti nitroso-13-naphthol, [C 10 H 6 0(NO)] 3 Co, insoluble in hydrochloric acid, being formed, whilst the corresponding nickel compound dissolves in hydrochloric acid.
Others which may be mentioned are salicylate of bismuth, salol, 0-naphthol and naphthalene.
Fittig and Erdmann's observation that phenyl isocrotonic acid readily yielded a-naphthol by loss of water was of much importance, since it afforded valuable evidence as to the constitution of naphthalene.