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Arylamines, color reactions

J) Color Reactions of Arylamines. To 10 ml of water in a test tube add one drop of aniline, and shake. Add one or two drops of a suspension of bleaching powder or a drop of a solution of sodium hypochlorite. Note the color. Repeat with o-toluidine, and with dimethylaniline. The production of color is due first to oxidation, and second, to condensation to complex colored compounds. [Pg.177]

In the ketone method, the central carbon atom is derived from phosgene (qv). A diarylketone is prepared from phosgene and a tertiary arylamine and then condenses with another mole of a tertiary arylamine (same or different) in the presence of phosphoms oxychloride or zinc chloride. The dye is produced directly without an oxidation step. Thus, ethyl violet [2390-59-2] Cl Basic Violet 4 (15), is prepared from 4,4 -bis(diethylamino)benzophenone with diethylaruline in the presence of phosphoms oxychloride. This reaction is very useful for the preparation of unsymmetrical dyes. Condensation of 4,4 -bis(dimethylamino)benzophenone [90-94-8] (Michler s ketone) with AJ-phenjl-l-naphthylamine gives the Victoria Blue B [2580-56-5] Cl Basic Blue 26, which is used for coloring paper and producing ballpoint pen pastes and inks. [Pg.271]

Arenediazonium salts undergo a coupling reaction with activated aromatic rings such as phenols and arylamines to yield brightly colored azo compounds, Ar—N=N—Ar. ... [Pg.944]

Arylamines are converted by diazotization with nitrous acid into arenediazonium salts, ArN2+ X-. The diazonio group can then be replaced by many other substituents in the Sandmeyer reaction to give a wide variety of substituted aromatic compounds. Aryl chlorides, bromides, iodides, and nitriles can be prepared from arenediazonium salts, as can arenes and phenols. In addition to their reactivity toward substitution reactions, diazonium salts undergo coupling with phenols and arylamines to give brightly colored azo dyes. [Pg.958]

For quantitative work, it is necessary to estimate the concentration of 5-amino-l-(P-D-ribofuranosyl)imidazole in aqueous solution. It seems that the only available method is the Bratton-Marshall assay, which was originally developed for the estimation of arylamines in biological fluids. The principle of the method is the spectrometric estimation of a salmon-pink colored dyestuff obtained by diazotation in situ, followed by coupling with /V-( 1 -naphthyl)ethyl-enediamine.65 The only remaining problem then is to know the molar extinction of this dye because pure samples of AIRs are not available. A value of 16800 at 520 nM was obtained for the dyes prepared from a model compound, 5-amino-l-cyclohexylimidazole-4-carboxylic acid (54), which is crystalline. A comparable molar extinction can be expected for the dye prepared from imidazole 55, if the carboxyl group does not exert too much influence on the chromophore. Actually, its influence is perceptible even with the naked eye, the dyestuff prepared from 53 having a somewhat different, wine-red color, with max>520 nM. The molar extinction for 55 is 17400 at 500 nM. When the decarboxylation of 54 was conducted under mild acidic conditions (pH 4.8, 50°C, 1 hour), estimation of 5-aminoimidazole 55 by the Bratton-Marshall method led to the conclusion that the reaction was almost quantitative.66 Similar conditions for the final decarboxylation were adopted in the preparation of samples of AIRs labeled with stable isotopes.58... [Pg.299]

The above proposal is supported by the lack of reaction of electron-deficient arylamines, such as p-N02-aniline and p-Et02C-aniline, in the copper-mediated reactions with lead acetates because of the inability of the amines to reduce Cu(II) to Cu(I). This lack of reduction is indicated by the lack of a color change upon addition of Cu(OAc)2 to a solution of either of the amines. Further, the presence of Cu(III) species may be responsible for the formation of arenes and polymeric species during the A-arylation of anilines that are easily oxidized (Scheme 11). [Pg.523]

Chemical Methods. Assay of these peptides by chemical methods is based upon the following reactions. Pteroylglutamic acid is reduced by metallic zinc in acid solution, and the liberated arylamine is diazotized and coupled with Bratton and Marshall reactant (90). The coupled compound is colored and therefore determined by photometry (305). p-Aminobenzoylpolyglutamic acid is also determined by the same method. [Pg.46]


See other pages where Arylamines, color reactions is mentioned: [Pg.1]    [Pg.39]    [Pg.147]    [Pg.855]    [Pg.4]   
See also in sourсe #XX -- [ Pg.177 ]




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Arylamine reactions

Arylamines

Arylamines reactions

Color reactions

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