Vesuvine

Bismarck brown, vesuvine, phenylene brown, Janus brown, -tannin brown a 3 ... 

The preparation of the first cationic azo dye, Vesuvin, was described by C. Martius in 1863. It is obtained by coupling diazotized m-phenylcncdiamine to an excess of the same amine. An analogous dye from toluylenediamine was reported by P. Gries in 1878. Chrysoidines, coupling products of aniline or toluidines to m-phenylenediamine or toluylenediamine, were reported by H. Caro in 1875 and O. N. Witt in 1876. 

Vesuvin and Bismarck Brown products are obtained when rn -phenylenedia-mine, 2,4- and 2,6-diaminotoluene, or mixtures thereof are treated with nitrite in acidic solution, or when a mixture of the amines and nitrite is acidified. The final products consist of mixtures of monoazo, disazo, and polyazo dyes, with the dis-azo species probably predominating in commercial products. The dye is salted out immediately after its formation, and thereby the formation of polyazo dyes is prevented. 

Liquid Vesuvin dye solutions can be obtained by diazotization and coupling of aromatic diamines [3] or, if desired, also in mixture with aromatic monoamines [4] in carboxylic acid solutions. 

Vesuvines are used chiefly for dyeing paper containing wood pulp. 

Bismarck Brown (vesuvine brown, basic brown 1, 0.5% pet. -h +... 

Other Names 1,3-Benzenediatnine, 4,4 -[l,3-phenyle-nebis(azo)]bis-, dihydrochloride C.I. 21000 C.I. Basic Brown 1, dihydrochloride Basic Brown G Basic Brown GX Basic Brown GXP Excelsior Brown Leather Brown Manchester Brown Phenylene Brown Vesuvin Vesuvine... 

Tertiary aliphatic amines and tertiary aromatic amines with substituted para position do not react with nitrous acid under these conditions. On alkalization the unchanged base precipitates, if insoluble in water. Tertiary amines with a free para position give nitroso derivatives which sometimes precipitate as insoluble hydrochlorides in contrast to nitro-soamines, these hydrochlorides are insoluble in ether. Upon alkalization of the solution the green nitroso derivative is set free, which can be extracted with ether (a blue extract). m-Phenylenediamine reacts with HNO2 under the formation of a brown dye (vesuvin), mercaptans with HNO2 give strongly colored thionitrous acids (esters are usually red). 

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