Monoazoic dyes

I-Naphthylamine readily diazotizes and couples to aromatic hydroxylic or basic compounds. It was thus used as a first component in a number of important monoazo dyes, but its use has been severely curtailed because of its potent carcinogenicity. It sulphonates to give naphthionic acid (l-naphthylamine-4-sul-phonic acid). 

Monoazo dyes Monoazo salts Monoazo yellow pigments Monobactams... 

Alkaline Coupling Process. Orange II [633-96-5] (21) (Cl Acid Orange 7 Cl 15510) a monoazo dye discovered ia 1876, serves as an example of the production of an azo dye by alkaline coupling. A suspension of diazotized sulfanilic acid (0.1 mol) is added to a solution (cooled to about 3°C) of 14.4 g 2-naphthol dissolved ia 15 g 30% sodium hydroxide, 25 g sodium carbonate, and 200 mL of water. The temperature should not be allowed to rise above 5°C. The reaction is heated until solution occurs and the dye is precipitated with 100 g sodium chloride. The mixture is cooled and filtered, and the product is dried. 

Other modifications of acid wool dyes have groups which react by nucleophilic substitution of basic groups ia proteia fibers (NH2 groups, etc). The iatroduction of Procion dyes by ICI ia 1956 was the most important development ia the field of technological azo dye chemistry. Chemically, many of the reactive dyes are prepared from the group of the anionic monoazo dyes (see Dyes, reactive). 

Certain chemical configurations required to produce suitable mordant dyes are shown ia the foUowiag examples of monoazo dyes. Substitutioa ia the two positioas ortho to the azo group may be Ulustrated by stmcture (45), ia which X represeats —OH, —OCH, —OCH2COOH, —COOH,... 

Commercial Disperse Azo Dyes. The first proposal to use insoluble dyes in suspension in an aqueous foam bath, ie, disperse dyes, to dye cellulose acetate was in 1921 (60). Commercialization of disperse dyes began in 1924 with the introduction of the Duranol dyes by British Dyestuffs Corporation (61) and the SRA dyes by British Celanese Company (62). In contrast to the acid monoazo dyes, derivatives of benzene rather than of naphthalene are of the greatest importance as coupling components. Among these components mono- and dialkylariifines (especially A/-P-hydroxyethyl-and A/-(3-acetoxyethylanifine derivatives) are widely used couplers. Nitrodiazobenzenes are widely used as diazo components. A typical example is CeUiton Scarlet B [2872-52-8] (91) (Cl Disperse Red 1 Cl 11110). 

Disperse reds are second only to blues as the most important disperse color manufactured. AU. commercial disperse reds are monoazo dyes. In 1988, Disperse Red 73 (98, R = CN) had production of 270 tons valued at nearly 1.6 million. Disperse Violet 24 (99) is produced from diazotized 2-hromo-4,6-dinitroani1ine by coupling with 2-(A/-butyl-y -toluidine)ethanol. 

Monoazo dyes such as Disperse Blue 11 (102) and Disperse Black 1 (103) are appHed to cellulose acetate as a dispersion and dyed in the usual way, then diazotized in situ and coupled in this instance, to 3-hydroxy-2-naphthoic acid forming the blue and black shades, respectively. 

There is a large number of heteroaromatic coupling components of very different structural types. l-Aryl-3-methyl-5-pyrazolones have been widely used for yellow and orange monoazo dyes since the end of the 19th century. Other types have become important as a source of new industrially produced dyes in the last two decades. In reviews on industrial aspects (e.g., Schwander, 1982) these coupling components are classified not on the basis of their structures, but from the viewpoint of what is important for tinctorial properties of the dyes obtained with these types of coupling components. Here we will use a structural approach to systematization. 

Methylene coupling components with carbonyl groups in a,a-positions are very important, particularly acetoacetanilide derivatives (Scheme 12-40, X=NHAr), for the production of yellow monoazo dyes and pigments (Hansa Yellows see Zollinger, 1991, p. 180). 

The complete reaction scheme is shown in Fig. 5.3-7, while Fig. 5.4-51 gives a simplified representation. 1-naphthol (A) is primarily coupled with diazotized sulphanilic acid (B) to form monoazo dyes coupled in para and ortho positions (p-R and o-R, respectively). This reaction is first order in both A and B. Each of the primary products can react with diazotized sulphanilic acid to form bisazo dye (5). Rate constants at 298 K and pH 10 are ku = 10600 m mof s k2i = 1 22 = 1.7 m mor s (see Fig. 5-4-51). 

On integration of the above system of differential equations until B has been completely consumed U, W, and Z values are obtained. Monoazo dyes concentrations are then calculated using Ekjns. (5.4-175) and (5.4-176). The concentration of 1-naphthol is calculated knowing its surplus for the reaction and the concentration of bisazo dye S can be determined from any of the mass balances ... 

The synthesis of monoazo dyes and pigments is represented by the symbolism... 

Mordant dyes generally have the characteristics of acid dyes but with the ability in addition to form a stable complex with chromium. Most commonly, this takes the form of two hydroxy groups on either side of (ortho to) the azo group of a monoazo dye, as illustrated for the case of C. I. Mordant Black 1 (151). The dye is generally applied to the fibre as an acid dye and then treated with a source of chromium, commonly sodium or potassium dichromate. As a result of the process, the chromium(vi) is reduced by functional groups on the wool fibre, for example the cysteine thiol groups, and a chromium(m) complex of the dye is formed within the... 

Rather more complex compounds that are currently being researched are the bolaform electrolytes [2-4]. Bolaform electrolytes are organic compounds possessing two cationic or two anionic groups linked by a flexible hydrocarbon chain the terminal groups may be aliphatic or aromatic (e.g. as in 10.1). Their interaction with sulphonated monoazo dyes in the presence of poly(vinylpyrrolidone) as substrate has been studied in detail. However, it remains to be seen what commercial developments take place with these interesting... 

The 1 1 copper complex azo dyes are used both as reactive dyes for cotton and as direct dyes for paper. (For definitions of reactive dyes, which form covalent linkages with the substrate, and direct dyes, which bind more weakly, see refs. 23 and 24, respectively.) Typical monoazo dyes are Cl Reactive Violet 1 (23) and Cl Reactive Blue 13 (25), and the bis-copper-ed dye, Cl Direct Blue 80 (26). The navy blue dye, Cl Reactive Blue 82 (27), is a typical disazo dye. 

Klabisiella sp. VN-31 Reactive Yellow 107, Reactive Red 198, Reactive Black 5, Direct Blue 71 Monoazo dyes RY107 and RR 198 were decolorized in 72 and 96 h the diazo dyes (RB5 and triazodye DB71) decolorized in 120 and 168 h [39]... 

Pseudomonas luteola Reactive azo dyes, Direct azo dyes and leather dyes The 59-99% color removal after 2-6 days static incubation, at dye concentration of 100 mg L 1, monoazo dyes showing fastest rate of decoloration [78]... 

Singh P, Sanghi R, Pandey A (2007) Decolorization and partial degradation of monoazo dyes in sequential fixed-film anaerobic batch reactor (SFABR). Bioresour Technol 98 2053-2056... 

Monoammonium phosphate (MAP), 77 120-121 72 67 78 835 manufacture of, 78 854 Monoatomic oxygen, 70 642 Monoazo dyes, 9 245, 395 Monoazo Orange, colorant for plastics, 7 374t... 

The aggregation behaviour and tautomerism of three 0,0 -dihydroxy and one o-hydroxy-o -methoxy monoazo dyes have been studied by UV-visible spectroscopy [17]. Evidence of monomer-dimer equilibria was obtained for all four of these mordant dye structures. Intermolecular hydrogen bonding between the hydroxy groups and hydrophobic interaction between aryl nuclei contribute to the dimerisation effect. 

Direct dyes of the disazo diarylurea type, such as Cl Direct Orange 26 (3.5) and Cl Direct Red 79 (3.21), are particularly prone to decomposition in high-temperature dyeing because molecular breakdown can occur by hydrolysis as well as by the reductive mechanism under alkaline conditions. Thus the ureido linkage in this red dye may be broken by hydrolysis to give two monoazo dye fragments (3.22), or the azo groups can be reduced to yield a diaminodiphenylurea (3.23) and two molecules of H acid (Scheme 3.3). 

Table 3.2 Rates of reduction of monosubstituted monoazo dyes by tin(n) chloride [23]...

Much of the available published data on the aqueous solubility of disperse dyes was accumulated during the 1960s in the course of studies of the mechanism of dyeing cellulose acetate with disperse dyes. Most of the dyes examined were low-energy types for dyeing acetate (Table 3.5). Particular attention was given to monoazo dyes derived from aniline or... 

Table 3.7 Substantivity of thienyl monoazo dyes with various coupling components [68]...

Early studies of the affinity of acid dyes for wool revealed noteworthy correlations with dye structure. For example, in four pairs of monoazo dyes differing only by replacement of a benzene by a naphthalene nucleus, the affinity increase in each pair was consistently within the range -4-6 to -6.3 kj/mol. In three related pairs of dyes, an additional sulpho group reduced the affinity by about -4 kj/mol. In a series of alkylsulphuric acids (ethyl, octyl, dodecyl) and in two series of monoazo dyes containing alkyl chains of increasing length, the increment per methylene group was consistently about -1.66 kj/mol. A close correlation between affinity and Mr was also obtained for a series of substituted phenylazo-l-naphthol-4- sulphonic acid dyes [115]. 

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