Sodium in boiling amyl 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 smell.
With diazotized benzidine it gives Congo red.
It can be readily diazotized, and the diazonium salt when boiled with alcohol yields aposafranine or benzene induline, C18H12N3.
Kehrmann showed that aposafranine could be diazotized in the presence of cold concentrated sulphuric acid, and the diazonium salt on boiling with alcohol yielded phenylphenazonium salts.
They may be prepared by the reduction of nitro compounds in alkaline solution (using zinc dust and alkali, or a solution of an alkaline stannite as a reducing agent); by oxidation of hydrazo compounds; or by the coupling of a diazotized amine and any compound of a phenolic or aminic type, provided that there is a free para position in the amine or phenol.
Para-oxyazobenzene (benzene-azo-phenol), C 6 H 5 N: N (1) C6H4 011(4), is prepared by coupling diazotized aniline with phenol in alkaline solution.
Meta-oxyazobenzene, C 6 H 5 N: N(1)C 6 H 4 OH(3), was obtained in 1903 by P. Jacobson (Ber., 1903, 36, p. 4 0 93) by condensing ortho-anisidine with diazo benzene, the resulting compound being then diazotized and reduced by alcohol to benzene-azometa-anisole, from which meta-oxyazobenzene was obtained by hydrolysis with aluminium chloride.
4), formed when diazotized naphthionic acid (a-naphthylamine-4-sulphonic acid) is boiled with dilute sulphuric acid (Nevile and Winther, Ber., 1880, 1 3, p. 1 949), or when sodium naphthionate is heated with concentrated caustic soda solution under pressure at 240°-260° C. (German patent 46307 (1888)).
In this process the amine salt is dissolved in absolute alcohol and diazotized by the addition of amyl nitrite; a crystalline precipitate of the diazonium salt is formed on standing, or on the addition of a small quantity of ether.
Replacement of -NH 2 by-OH:-The amine is diazotized and the aqueous solution of the diazonium salt is heated, nitrogen being eliminated and a phenol formed.
Similar results have been obtained by using diazotized para-anisidine, a synand an anticompound being formed, as well as a third isomeric cyanide, obtained by evaporating para-methoxybenzenediazonium hydroxide in the presence of an excess of hydrocyanic acid at ordinary temperatures.
The esters of the aliphatic amino acids may be diazotized in a manner similar to the primary aromatic amines, a fact discovered by T.
Guaiacol may be obtained directly from beechwood tar, from pyrocatechin by methylation with potash and potassium methyl sulphate at 180°, or from anisol by nitration, reduction of the ortho-nitroanisol to amino-anisol, which is then diazotized and boiled with water.
Among such dyestuffs are chrysamine or flavophenine, obtained from salicylic acid and diazotized benzidine, and congo red obtained from sodium naphthionate and diazotized benzidine.
It is a crystalline solid which melts at 56° C. and boils at 204° C. It can only be diazotized in the presence of concentrated sulphuric acid, and even then the free diazonium sulphate is not stable, readily passing in the presence of water to a-oxypyridine.