Bromamine acid

Among anthraquiaoae dyes (see Dyes, anthraquinone). Acid Blue 78 [6424-75-5] C2 H25BrN20 S -Na, or Alizarin Pure Blue B, is a wool dye. Bromamine acid [116-81-4] (l-amiao-4-bromoanthraquiaoae-2-sulfonic acid), C24HgBrNO S, is a useful dye iatermediate. A number of bromo anthraquiaoae, pyrathroae, and benzanthrone dyes are known. 

Production of anthraquinone reactive dyes based on derivatives of bromamine acid (8) was first commercialized in 1956. Some improvements have been made and now they ate predominandy used among the reactive blue dyes. Cl Reactive Blue 19 [2580-78-1] (9) (Cl 61200) (developed by Hoechst in 1957) has the greatest share among them including dye chromophores other than anthraquinones. 

Efforts to raise the alpha-selectivity have been made. Thus nitration of anthraquinone using nitrogen dioxide and ozone has been reported (17). l-Amino-4-bromoanthraquinone-2-sulfonic acid (bromamine acid) [116-81 -4] (8) is the most important intermediate for manufacturing reactive and acid dyes. Bromamine acid is manufactured from l-aminoanthraquinone-2-sulfonic acid [83-62-5] (19) by bromination in aqueous medium (18—20), or in concentrated sulfuric acid (21). l-Aminoanthraquinone-2-sulfonic acid is prepared from l-aminoanthraquinone by sulfonation in an inert, high boiling point organic solvent (22), or in oleum with sodium sulfate (23). 

Contamination by water-insoluble reaction by-products such as l-amino-2,4-dibromoanthraquinone affects the quaUty of dyestuff signiftcandy. Therefore, several methods for purification have been reported. Examples are extraction of impurities with organic solvent (18), or precipitation of bromamine acid from concentrated (60—85%) sulfuric acid (26). 

Many anthraquinone reactive and acid dyes are derived from bromamine acid. The bromine atom is replaced with appropriate amines in the presence of copper catalyst in water or water—alcohol mixtures in the presence of acid binding agents such as alkaU metal carbonate, bicarbonate, hydroxide, or acetate (Ullmaim condensation reaction). 

Cl Reactive Blue 19 (9) is prepared by the reaction of bromamine acid (8) with y -aminophenyl-P-hydroxyethylsulfone [5246-57-1] (76) ia water ia the presence of an acid-hinding agent such as sodium bicarbonate and a copper catalyst (Ullmann condensation reaction) and subsequent esterification to form the sulfuric ester. 

Reactive green dyes are obtained by combination of a blue chromophore (a bromamine acid derivative) and a yellow chromophore with a tria2inyl group. Green [70210-47-8] (87) (104) is an example. The yellow chromophore of this dye was invented by ICI for diclilorotria2ine dyes and exhibits good lightfastness and chlorine resistance. 

Scheme 4.5 Reaction of bromamine acid with aromatic amines...

Nucleophilic substitution reactions, to which the aromatic rings are activated by the presence of the carbonyl groups, are commonly used in the elaboration of the anthraquinone nucleus, particularly for the introduction of hydroxy and amino groups. Commonly these substitution reactions are catalysed by either boric acid or by transition metal ions. As an example, amino and hydroxy groups may be introduced into the anthraquinone system by nucleophilic displacement of sulfonic acid groups. Another example of an industrially useful nucleophilic substitution is the reaction of l-amino-4-bromoanthraquinone-2-sulfonic acid (bromamine acid) (76) with aromatic amines, as shown in Scheme 4.5, to give a series of useful water-soluble blue dyes. The displacement of bromine in these reactions is catalysed markedly by the presence of copper(n) ions. 

Milling dyes with very good wet fastness are obtained by the reaction of one mole of a diamine with two moles of bromamine acid, as in the case of Cl Acid Blue 127 (6.35). This dye is suitable for dyeing wool bright blue from a neutral or weakly acid bath. 

Rate constants and the products formed in the hydrolysis of Cl Reactive Red 194 (7.76) at 50 °C and pH values in the 10-12 region were determined by high-pressure liquid chromatography. In addition to the normal hydrolysis of the two reactive systems, the imino link between the triazine and benzene nuclei was also hydrolysed [67]. The heterobifunctional copper formazan dye Cl Reactive Blue 221 and two blue anthraquinone monofunctional reactive dyes of the bromamine acid type, namely the aminochlorotriazine Blue 5 and the sulphatoethylsulphone Blue 19, were compared in terms of their sensitivity to... 

Two different chemical classes contribute to this sector. Initially it was entirely dominated by anthraquinone dyes typified by structure 7.102. The dye bases for attachment of haloheterocyclic (Z) systems are prepared by condensing bromamine acid (7.103) with various phenylenediamines. The outstandingly successful Cl Reactive Blue 19 (7.3 7) is the... 

Simultaneously with Hansa Yellow G, compound 84 was first described as early as 1909 by Farbenfabriken Bayer. Its preparation starts from l-amino-4-bro-moanthraquinone-2-sulfonic acid (bromamine acid) 85. Dimerization is achieved through the Ullmann reaction, i.e., treatment with fine-grain copper powder in dilute sulfuric acid at 75°C. The separated intermediate, the disodium salt of 4,4 -diamino-l,l -dianthraquinonyl-3,3 -disulfonic acid 86, is heated to 135 to 140°C in the presence of 80% sulfuric acid in order to cleave the sulfonic acid groups [7] ... 

Bromamine acid, l-amino-4-bromoanthraquinone-2-sulfonic acid, is a very useful intermediate for producing bine dyes. Condensation of this intermediate with aromatic amines in the presence of a copper catalyst offers a straightforward route to many commercially important acid and reactive dyes, for instance Cl Acid Blue 40 and Cl Reactive Bine 19 (Fignre 2.13). 

Figure 2.13 Blue dyes from bromamine acid.

Compared to direct azo dyes, the direct anthraquinone dyes have lower tinctorial strengths and are therefore far less economical to use. They have lost most of their importance. Only a few special green dyes have retained their importance. Direct green cotton dyes can be produced by coupling a blue bromamine acid dye and a yellow azo dye via ureido or diaminotriazine bridges. 

A key intermediate in the synthesis of anthraquinone acid dyes is bromamine acid. 

The synthesis of C.I. Acid Blue 127 takes place according to the route shown in Fig. 13.119. A key step in the synthesis is the formation of diamine 37, which is produced in two steps from V-sulfomethylaniline (1) condensation with acetone and (2) hydrolysis to remove the protecting group. At this point, one molecule of diamine 37 is condensed with two molecules of bromamine acid to form the dye. 

Similarly, dyes 40 and 41 are prepared by condensing 2,5-diaminobenzenesulfonic acid with bromamine acid, which reacts first at the less hindered amino group, followed by a reaction with cyanuric chloride to introduce the reactive group. These steps produce dye 41 and... 

Fig. 13.121. Synthesis of three reactive blue dyes from bromamine acid.

Chlorobenzene is employed in the synthesis of certain amino-containing vat dye intermediates. When reacted with phthalic anhydride, the product is 2-chloroanthraquinone, which, with ammonia, is converted readily into 2-aminoanthraquinone (61). Other routes include replacement of halogen by amino groups, with ammonia or ammonium salts of urea, and alkyl- and aryl amines to afford secondary amines. Modification of the amino group by alkylation, with dimethyl sulfate, alkyl halides or esters of toluenesul-fonic acids, is of synthetic value. Arylation of the amino groups is of importance only in the reaction between aminoanthraquinones and nitro- or chloroanthraquinones to yield dianthraquinonylamines, or anthrimides48. For example, the reaction between 62 and 63 yields 64, which can then be converted into carbazole 65, Cl Vat Brown R (Scheme 14). Amination of haloanthraquinones such as l-amino-4-bromoanthraquinone-2-sulfonic acid (bromamine acid) (66), prepared from 1-aminoanthraquinone, is of industrial use. 

Bromamine acid (l-amino-4-bromoanthraquinone-2-sulfonic acid) is the most important intermediate for the production of acid anthraquinone dyestuffs. 

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