Violet, Acid Diamine

The reaction between tetrazo-compounds and y-amidonaphthol-sulphonic acid may be effected in either alkaline or slightly acid solution, and the products differ according to which condition is observed. The exact reason for this behaviour has not been explained. For example, in the preparation of diamine blades R and B, and diamine blue-black E, the combination of the tetrazo-compound with y-amidonaphtholsnlphonic acid is effected in alkaline solution, while in the cases of Diamine Violet and Fast Red a slightly acid solution is used. 

For the detection of ketosteroids, an m-dinitrobenzene solution can be used (17-keto-steroids, violet 3-keto-A" groups, blue). A" -3-Oxo steroids and A" -3-oxo steroids can be distinguished using a phthalic acid-/7-phenylene-diamine reagent, which gives yellow and orange-brown colors, respectively. Detailed discussion of the... 

In another analytical procedure, the diamine from the diisocyanate is obtained from the filtrate of the acidified alkaline hydrolysis product and can be determined quantitatively by colorimetric methods. If preliminary analysis has indicated 1,5-naphthalene diisocyanate, the filtrate is oxidized with periodic acid and gives a violet-pink colour. For other diisocyanates, colour formation also suitable for colorimetric analysis can be obtained by... 

Related to the xanthene dyes are the acridines, azines, oxazines, and thiazines. Acridine Yellow results from the fusion of toluene-2,4-diamine with glycerin and oxalic acid, followed by oxidation with ferric chloride. Basic Orange 15 (Phosphine) is a by-product of the manufacture of Basic Violet 14 (Fuchsine) and is an acridine dye. 

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