Nitroaniline dyes

Para Red is usually dyed by passing the fabric which has been treated with jS-naphthol and dried through an ice-cold solution of the diazo compound prepared from p-nitroaniline. Dyes which are applied in this way are often called ice-colors. Para red is very stable and is used in the manufacture of certain varieties of bright red paint. 

Ammonium persulfate Arsenic trioxide dye, animal Sodium arsenate dye, anodized aluminum Acid violet 49 dye, aq. inks Direct green 1 dye, aq. writing inks Direct blue 1 dye, azoic acetate 2-Methoxy-5-nitroaniline dye, azoic cotton 2-Methoxy-5-nitroaniline dye, azoic nylon 2-Methoxy-5-nitroaniline dye, azoic silk 2-Methoxy-5-nitroaniline dye, basic acrylic fiber Basic blue 9 Basic green 4 dye, basic bast Basic orange 14 dye, basic cotton Basic brown 1 dye, basic leather Basic blue 9 Basic violet 10 dye, basic paper Basic violet 10 dye, basic silk Basic orange 14 dye, basic textiles Basic brown 1 dye, bast... 

Benzyl alcohol 2-Methyl-5-nitroaniline dyeing, paper Direct blue 53 Trypan blue... 

White crystals, m.p. 114" C. Manufactured by reacting aniline with excess ethanoic acid or ethanoic anhydride. Chief use is in the manufacture of dye intermediates such as p-nitro-acetanilide, p-nitroaniline and p-phenylene-diamine, in the manufacture of rubber, and as a peroxide stabilizer. 

Among the acid colors of green, brown, and black shades, three disazo dyes are important Acid Green 20 (42) -nitroaniline------ H-acid... 

Dye formation is complex because shading is achieved by employing several developers and several couplers in the same dye bath. The process is illustrated by -phenylenediamine, which is oxidized by the peroxide to a quinone diimine. This short-Hved intermediate can react, for example, with resorcinol to yield a brownish indoaniline. Table 17 provides some insight into the many interactions that exist from just a few components. Further shading is possible by including semipermanent colorants (see Table 16), especially nitroaniline derivatives. 

Phenols (capable of coupling) Fast blue salt B, fast blue salt BB, fast black salt K, diazotized sulfanilic acid (Pauly s reagent) diazotized sulfanilamide or 4-nitroaniline Intensely colored azo dyes are formed. Catecholamines [20, 3S], imidazoles [21] and amines capable of coupling also react. [3, 17]... 

Compression-molded devices of poly(N-palmitoyl hydroxyproline ester) (side chain length 16 carbons), poly(N-decanoylhydroxy-proline ester) (side chain length 10 carbons), and poly(JN-hexanoyl-hydrox roline ester) (side chain length 6 carbons) were prepared with dye contents of 1,5,10, and 20% of either -nitroaniline or acid orange. Release curves were obtained by placing the loaded devices into phospate buffer (pH 7.4) at 37 C. The amount of released dye was followed spectrophotometrically in the usual fashion. 

Activated sludge 4-Nitroaniline (an intermediate of dye), yeast extract Acinotobacter sp., Citrobacter freundii, Klebsiella oxytoca [14]... 

Aromatic amines from the (bio)degradation of azo dyes or nitroaromatic explosives must also be monitored, mainly through the sum of their concentrations. However, taking account of the standard solution used for the calibration of the colorimetric reference method (4-nitroaniline), some attempts are proposed for the on-line specific determination of the most important single compounds [44,45]. 

Two commercial disazo disperse dyes of relatively simple structure were selected for a recent study of photolytic mechanisms [180]. Both dyes were found to undergo photoisomerism in dimethyl phthalate solution and in films cast from a mixture of dye and cellulose acetate. Light-induced isomerisation did not occur in polyester film dyed with the two products, however. The prolonged irradiation of Cl Disperse Yellow 23 (3.161 X = Y = H) either in solution or in the polymer matrix yielded azobenzene and various monosubstituted azobenzenes. Under similar conditions the important derivative Orange 29 (3.161 X = N02, Y = OCH3) was degraded to a mixture of p-nitroaniline and partially reduced disubstituted azobenzenes. 

Heterocyclic coupling components are widely used in the disperse dye field for the production of yellow dyes. Numerous conventional dyes are based on simple pyrazolones, often combined with an o-nitroaniline diazo component, the o-nitro group being particularly favourable in ensuring good light fastness. Cl Disperse Yellow 8 (4-73), which uses a very simple pyrazolone coupling component, is an example. 

In general, metal complexes formed from bidentate azo chromogens are little used as dyes but do find important applications as pigments (section 2.3.2). Rare exceptions exist, however, such as the nickel(II) complex of p-nitroaniline— BON acid (5.11). This has been used for bordeaux prints of high light fastness on cotton fabrics. Two possible modes of bidentate attachment to the nickel atom can be envisaged (Scheme 5.2). 

The photometric determination of mixtures of aniline, p-nitroaniline and o-nitroaniline was described. Distribution coefficients and separation efficiency of these compounds by LLE in various solvents were compared517. Substituted nitroanilines such as 2-chloro-4-nitroaniline and 2,4-dinitroaniline are intermediates in the manufacture of the dye D C Red No. 36 and were identified as impurities by RP-LC518. A spectrophotometric method was developed for the determination of aniline and m-nitroaniline in a mixture of aniline and nitroaniline isomers by derivatization with 5,7-dichloro-4,6-dinitrobenzofuroxan (244). The relative error of the determination is <5%519. See also Section IV.D.3.b for similar derivatives. 

This system resolved the aniline peak (retention time (rt) = 2.67 min) from the benzidine peak (rt = 2.27 min) as can be seen in Figure 2. Other potential interferences were selected for study by looking at the expected fragments from the reduction of various dyes. Reduced dye samples were spiked with aniline (rt = 2.67 min), -aminophenol (rt = 1.97 min), -phenylenediamine (rt = 1.93 min) and -nitroaniline (rt = 3 16 min). None of these materials interfered with the detection of the benzidine peak. To determine if other types of dyes might interfere with the analysis, two sets of filters were spiked at low and high levels separately with C.I. Direct Red 28 (13 7 yg and 137 yg), C.I. Direct Blue 53 formulation (o-tolidine-based) (21.2 yg and 212 yg) and C.I. Direct Blue 8 formulation (o-dianisidine-based)(23.3 yg and 233 yg). 

Sulfur Bake. The yellow, orange, and brown sulfur dyes belong to this group. The dyes are usually made from aromatic amines, diamines, and their acyl and nuclear alkyl derivatives. These may be used in admixture with nitroanilines and nitrophenols or aminophenols to give the desired shade. The color formed is said to be the result of the formation of the thiazole chromophore, evident in dye structure (1). 

Figure 2. A, chromatogram from elution of 100 mL of enriched drinking water (Athens, GA) fortified with 1, 0.26 pg of caffeine 2, 0.050 gig of m-nitroaniline 3, 0.44 pg of atrazine 4, 0.75 pg of 2,6-dichloroaniline 5, 0.43 fig of N-nitrosodiphenylamine 6, 0.85 pg of decafluorobiphenyl (not detected) and 7, 0.41 pg of disperse red dye 13. B, chromatogram from elution of 100 mL of enriched drinking water (Athens, GA). Conditions for both enrichments 100-mL samples enriched on an ODS-packed precolumn at 5 mL/min. Analytical separation was on Partisil-10, ODS-2, 250-mm X 4.6-mm i.d. column. Mobile-phase gradient was 10% to 90% (v/v) acetonitrile in distilled-deionized water at 5%/min, and flow rate was 1.0 mL/min. Detection was at 254 nm. (Reproduced with permission from reference 17.

Chaube et al. [47] investigated the determination of ultratrace concentrations of nitrite in sulfuric acid extracts in soil. In their method, the nitrite is used to diazotise o-nitroaniline and the o-nitrophenyldiazonium chloride produced is coupled with N-naphlhylcthylcncdiaminc hydrochloride. The red-violet dye produced is extracted into isoamyl alcohol and evaluated spectrophotometrically at 545 nm. Beer s law is obeyed in the range 0.1 to 0.6 mg nitrate per litre of solution. 

Whereas p -naphthylaminesulfonic acids always couple at the adjacent a position, in a-naphthylaminesulfonic acids, the coupling location is influenced by the position of the sulfonic acid group 1,6-, 1,7-, and 1,8-naphthylaminesulfonic acids couple at the 4-position 1,5-naphthylaminesulfonic acid (Laurent acid) only couples with very strong couplers (e g., 2,4-dinitroaniline), mainly at the 4-position. With diazotized aniline, chloroaniline, or diazotized aniline sulfonic acids the 2-aminoazo dyes are obtained, but with diazotized nitroaniline, mixtures of the 2-and 4-coupling products form (Scheme 2.1). 

Of all the disperse azo dyes, this class has the greatest economic importance. Commercial products are most often represented by structure 2, in which 4-nitroaniline [100-01-6] and its substituted derivatives constitute the diazo component. 

Strongly negatively substituted 4-nitroanilines, such as 2,4,6-trinitroaniline [489-98-5], 2,4-dinitro-6-cyanoaniline [22603-53-8], 2-methanesulfonyl-4-nitro-6-cyanoaniline, and 2,6-dicyano-4-nitroaniline [20033-48-1], are difficult to diazo-tize, and their diazonium salts tend to decompose extensively during the coupling process [15], This results in diminished yields and loss of clarity of the dyes. 

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