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NAPHTHYLAMINES, or AMINONAPHTIALENES

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Originally appearing in Volume V19, Page 169 of the 1911 Encyclopedia Britannica.
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NAPHTHYLAMINES, or AMINONAPHTIALENES , C1oH7NH2, the See also:naphthalene homologues of See also:aniline, in contrast to which they may be prepared by See also:heating the See also:naphthols with See also:ammonia-See also:zinc chloride. a-Naphthylamine is prepared by reducing a-nitronaphthalene with See also:iron and hydrochloric See also:acid at about 70° C., the reaction mixture being neutralized with See also:milk of See also:lime, and the naphthylamine See also:steam-distilled. It may also be prepared (in the See also:form of its acetyl derivative) by heating a-naphthol with See also:sodium acetate, ammonium chloride and acetic acid (A. See also:Calm, Ber., 1882, 15, p. 616); by heating a-naphthol with See also:calcium chloride-ammonia to 2700 C.; and by heating pyromucic acid, aniline, zinc chloride and lime to 30o C. (F. Canzonieri and V. Oliveri, See also:Gaza., 1886, 16, p. 493). It crystallizes in colourless needles which melt at 50° C. It possesses a disagreeable faecal odour, sublimes readily, and turns See also:brown on exposure to See also:air. Oxidizing agents (ferric chloride, &c.) give a See also:blue precipitate with solutions of its salts.

Chromic acid converts it into a-naphthoquinone. Sodium in boiling amyl See also:

alcohol reduces it to aromatic tetrahydro-a-naphthylamine, a substance having the properties of an aromatic amine, for it can be diazotized and does not possess an ammoniacal See also:smell. Since it does not form an addition product with See also:bromine, reduction must have taken See also:place in one of the nuclei only, and on See also:account of the aromatic See also:character of the See also:compound it must be in that See also:nucleus which does not contain the amino See also:group. This tetrahydro compound yields adipic acid, (See also:CH2)4(See also:CO2H)2, when oxidized by See also:potassium permanganate. The a-naphthylamine sulphonic acids are used for the preparation of See also:azo dyes, these dyes possessing the important See also:property of See also:dyeing unmordanted See also:cotton. The most important is naphthionic acid, 1-amino-4-sulphonic acid, produced by heating a-naphthylamine and sulphuric acid to 170-180° C. with about 3% of crystallized oxalic acid. It forms small needles, very sparingly soluble in See also:water. With diazotized See also:benzidine it gives See also:Congo red. 13-Naphthylamine is prepared by heating 0-naphthol with zinc chloride-ammonia to 200-210° (V. Merz and W. Weith, Ber., 1880, 13, 1300); or in the form of its acetyl derivative by heating 0-naphthol with ammonium acetate to 270-280 C. It forms odourless, colourless plates which melt at 111-112° C.

It gives no See also:

colour with ferric chloride. When reduced by sodium in boiling amyl alcohol See also:solution it forms alicyclic tetrahydro-0-naphthylamine, which has most of the properties of the aliphatic See also:amines; it is strongly alkaline in reaction, has an ammoniacal odour and cannot be diazotized. On oxidation it yields ortho-carboxy-hydrocinnamic acid, HO2C•See also:C6H4•CH2.CH2•CO2H. Numerous sulphonic acids derived from 0-naphthylamine are known, the more important of which are the 2.8 or Badische, the 2.5 or See also:Dahl, the 2.7 or 8, and the 2.6 or Bronner acid. Of these, the 3-acid and Bronner's acid are of more value technically, since they combine with ortho-tetrazoditolyl to produce See also:fine red dye-stuffs.

End of Article: NAPHTHYLAMINES, or AMINONAPHTIALENES

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