Diazoamido-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. 

After diazotisation is completed the liquid is allowed to run into an alkaline solution of the phenol or its sulphonic acid, care being taken that the mixture remains alkaline. After some time the dyestuff is salted out, and is generally filtered through a filter-press. The combination of diazo-compounds with amines is somewhat more complicated. Some of these, for instance metaphenylenediamine, combine with diazo-compounds in neutral aqueous solutions while others, like diphenylamine, are dissolved in alcohol, and a concentrated solution of the diazo-compound gradually added. In the manufacture of amidoazobenzene and all compounds in which an intermediate formation of a diazo-amido-compound takes place, a large excess of the amine has to be employed, to hold the diazoamido-compound formed in solution. 

The diazoamido-compounds are yellow substances which do not dissolve in acids. They are far more stable than the diazo-compounds, and may be recrystallised without decomposition. Still, if they are heated rapidly they puff up suddenly and decompose. In their reactions they behave like a mixture of a diazo-compound and an amine. If, e.g., they are boiled with hydrochloric add, they decompose with evolution of nitrogen, and form a phenol and an amine ... 

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

The diazo-compounds also have the power of combining with secondary amines to form diazoamido-compounds, — the combinations with an alkaloid base, piperidine C4HnN ... 

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 ... 

While the amidoazobenzene does not unite with hydrochloric acid, the new molecule of the amine formed in the reaction does, and thus there is a molecule of the amine hydrochloride present, which again causes the transformation, so that a small amount of the hydrochloride may transform an indefinitely large amount of the diazoamido-compound. 

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