Amidoazo-compounds

The formation of amidoazo-compounds by molecular rearrangement of diazoamido-compounds. The nitrous acid and nitric acid were oxidation products of the ammonia which was added. 

As a rule animal fibres are not capable of decomposing the salts of acid dyestuffs, and in dyeing the colour-acids have to be set at liberty by the addition of a stronger acid to the dye-bath. Certain colour-acids, for example the sulphonic acids of amidoazo-compounds, have a different colour to that of their alkali salts. In dyeing wool with such colour-acids, the shade produced is that of f the salts and not that of the colour-acid, so that in such cases wool evidently plays the role of a base. 

It cannot be denied that many reactions of oxy- and amidoazo-compounds, especially those of the ortho series, are easily explained on the assumption that these formulae are correct but, on the other hand, amidoazo-compounds are capable of reacting as true amines. 

As has already been stated, the azo-compounds react like amido-or hydroxyl compounds in certain cases for example, all amidoazo-compounds yield diazo-compounds. It is possible that two, forms exist in such cases, and that these react in one way or another according to circumstances. 

The sulphonic acids of the amidoazo-compounds are interesting in this respect. Apparently they are incapable of existing in the free state, at least from their colour it appears that the formation of a salt takes place between the sulpho-group and the basic group. 

Amidoazo-compounds, of which the simplest representative is amidoazobenzene, are eonverted into the corresponding diazoazo-compounds, which latter, like simple diazo-compounds, react with amines and phenols, azo-dyes being formed. Amidoazosulphonic acids behave in the same way. 

Other dyestuffs derived from amidoazo-compounds are comprised in the following table —... 

Besides the reactions already mentioned, safEranines are also formed by action of amines on amidoazo-compounds [45], by oxidation of the latter, and by oxidation of the mauveines [28]. The formation from amidoazo-compounds comes under one of the general methods, as it doubtless depends on the splitting up of the azo-compoimd into a paradiamine and a monamine. 

The indulines are formed in a great number of reactions. Nearly all azo-, azoxy-, and amidoazo-compounds, if heated ivith salts of aniline or other aromatic amines, produce indulines, and the dyestuffs formed on oxidation of aromatic amines under certain conditions belong in all probability to this class. It is difficult to say with certainty to what extent the products of different reactions are identical with one another. 

If a diazoamido-compound is warmed with an amine in the presence of some amine hydrochloride, transformation to the isomeric amidoazo-compound takes place ... 

U. REACTION THE MOLECULAR TRANSFORMATION OF A DIAZO-AMIDO-COMPOUND INTO AN AMIDOAZO-COMPOUND... 

If a diazoamido-compound is heated with an amine and some amine hydrochloride, it goes over to an amidoazo-compound. The most probable cause of the reaction is that the amine residue of the diazo-amido-compound unites with a benzene-hydrogen atom of the amine hydrochloride, upon which the diazo-residue unites with the residue of the amine salt to form amidoazobenzene ... 

If amidoazobenzene is reduced, p-phenylene diamine and aniline are obtained. The transformation accordingly results in the formation of a compound in which the ainido-groups are in the para position, which always happens when the para position is unoccupied. The amidoazo-compounds possess weakly basic properties but if their salts are treated with much water, they partially dissociate. 

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