Triazo-group

Replacement of Triazo Groups with Fluorine in the Acid Decomposition... 

Nitro-4-triazophenylarsenoxide is prepared from 8-nitro-4-aminophenyldichloroarsine and not by reduction of the arsinie acid, since the triazo-group also undergoes reduction in the latter case.- The oxide is a colourless powder, easily soluble in alkalis and alcohols. 

Azide formates and acyl azides decompose at substantially lower temperature than do alkyl and aryl azides, owing to a decrease in the double bond character of the N-N2 bond as a result of conjugation between the carbonyl and triazo groups. Acyl azides, in particular decompose at or slightly above room temperature and in some cases a concerted mechanism has been proposed , viz. 

For purposes of org nomenclature the terms azido" and "triazo are used syn-omously in the literature. The aryl azides are often called in German diazoimides. Aliphatic diazo compds contain the group = CN2, represented as a resonance hybrid of the structure... 

In connection with the hydrolysis of benzoylazide, it is interesting to recall that triazo-benzene or phenylazide, C H6N4, is so stable that it cannot be directly hydrolyzed by the action of acids on alkalies to form hydrazoic acid, but E. NSiting and E. Grandmougin were able to show that if an acidic radicle, say a nitro-group, be introduced into the phenyl radicle—say by treatment with nitric acid whereby p-nitrophenylazide, C,H., N02)N3, is formed—the product is readily hydrolyzed by alkali-lye. Similar remarks apply to the ortho-derivatives, while, curiously enough, the meta-derivatives are not so readily hydrolyzed. 

Azido or Triazo- Compounds, contg one or more N3 groups, are the org derivatives of hydrazoic acid, HN3. These compds are usually unstable to heat and often decompose violently. They may be divided into four classes ... 

The most common "monovalent nitrogen groups which can be substituted by fluorine are the nitro (NO2). azido (N3), triazo (N = NNR2), and amino (NH2) groups. Replacement of the amino group is facilitated by transformation to either the corresponding activated diazo-nium salt (N2 by diazotization. or by quaternization to the ammonium salt (NRj" X ). 

The product distribution in the cycloaddition of 4-methyI-3//-1.2.4-triazole-3,5(4//)-dionc and 9-(2-propenylidene)benzonorbornene and the 5,8-dimcthoxy derivative favors the c/nd-triazo-lidinediones 1 a and 1 b, i.e., the dienophile adds anti to the benzo group, but with the 5,6,7,8-te-trafluoro derivative the ratio falls to unity39. This cycloaddition is considered to proceed via a two-step dipolar mechanism, via a zwitterion intermediate which, in the cases of benzo and dimethoxybenzo derivatives, can be stabilized by charge delocalization into the aromatic ring. 

Dye Classification Based on chemical structure or chromophore, 20-30 different groups of dyes can be discerned. Azo (monoazo, disazo, triazo, polyazo), anthraquinone, phtha-locyanine and triarylmethane dyes are quantitatively the most important groups. Other groups are diarylmethane, indigoid, azine, oxazine, thiazine, xanthene, nitro, nitroso, methine, thiazole, indamine, indophenol, lactone, aminoketone and hydroxyketone dyes and dyes of undetermined structure (stilbene and sulphur dyes). The vast array of commercial colourants is classified in terms of colour, structure and application method in the Colour Index (C.I.), which has been edited since 1924 (and revised every three months) by the Society of Dyers and Colourists and the American Association of Textile Chemists and Colorists. Each dye is given a C.I. generic name determined by... 

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