Dyes disazo

The simplest route to disazo dyes is by using / -am inoazobcnzcnc [60-9-3], As p-aminoazobenzene has been classified in the EU as carcinogenic, the use of derived disazo dyes like Disperse Red 151, DisperseYellow 7,Disperse Yellow23, and DisperseYellow56 has diminished. 

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Disazo dyes Disazo yellow pigments Discharge printing Disclosure... 

Chemically, the azo class is subdivided according to the number of azo groups present into mono-, dis-, tris-, tetrakis-, etc. Mono- and disazo dyes are essentially equal in importance, trisazo dyes are less important, and tetrakisazo dyes, except for a few, are much less important. For this reason, substances with more than three azo linkages are generally included under the heading of polyazo dyes. The Colour Index]isX.s the azo dyes as follows ... 

Primary Disazo Dyes. The foHowing dyes are examples of the four types of primary disazo compounds. Their stmctures appear in Figure 3. 

Fastusol Yellow 66 [91-34-9] (25) (Cl Direct YeUow 4 Cl 24890) is a symmetrical primary disazo dye from a tetrazo component (4,4 diamino-2,2 stilbene-disulfonic acid [81-11-8],... 

Amidine Fast Red F [2429-84-7] (26) (Cl Direct Red 1 Cl 22310) is an iinsymmetrical primary disazo dye from a tetrazo component (benzidine... 

Resorcine Brown R [5850-16-8] (27) (Cl Acid Brown 14, Cl 20195) is a symmetrical primary disazo dye with bihmctional coupling component (resorcinol). 

Calcocid Blue Black Ex [1064-48-8] (28) (Cl Acid Black 1 Cl 20470) is an unsymmetrical primary disazo dye with bihmctional coupling component (H-acid). 

Secondary Disazo Dyes. There are about 250 dyes of known constitutions in this group. They are made by diazotizing an aminoazo compound, the amino group of which derives from the original coupling component and coupling it to a suitable intermediate. Intrasil Orange YBLH... 

Miscellaneous Disazo Dyes. Another group of disazo dyes is prepared by condensation of two identical or different aminoazo compounds commonly with phosgene, cyanuric chloride, or fumaryl dichloride, the fragments of which act as blocking groups between chromophores. 

Economically, the most important acid red is Acid Red 151. This disazo dye (39) is obtained by coupling -aminophenylazo)benzenesulfonic acid to 2-naphthol. 

Other disazo dyes with good substantivity and high wet-fastness properties on polyamides are Acid Red 114 (40), made by coupling o-toHdine to phenol which is then coupled to G-acid, followed by reaction of the phenoHc hydroxyl group with -toluenesulfonyl chloride, and Acid Blue 113 (41) (metanilic acid — 1-naphthylamine — 8-anilino-1-naphthalenesulfonic acid). 

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

Dyes with OjO -hydroxycarboxyazo and OjO -hydroxyaminoazo ligands are important for yeUow shades. Anthranilic acid [118-92-3] is used advantageously with various couplers. OjO -Hydroxyaminoazo dyes are also used to obtain green and brown shades. An example is Monochrome Brown EB [3564-15-6] (54) (Cl Mordant Brown 1 Cl 20110) an unsymmetrical primary disazo dye. 

Disazo JMordant Dyes. Examples of disazo dyes are Diamond Alizarine Black SN [3258-74-0] (55) (Cl Mordant Black 25 Cl 21725) and a secondary disazo dye. Diamond Black F [8027-29-0] (56) (Cl Mordant Black 5 Cl 26695). 

Direct dyes are defined as anionic dyes substantive to ceUulosic fibers (cotton, viscose, etc), when applied from an aqueous bath containing an electrolyte. Before the discovery of Congo Red in 1884, only mordanted cotton could be dyed. Congo Red [573-58-0] (62) (Cl Direct Red 28 Cl 22120) a primary symmetrical disazo dye, which is made readily from bisdiazotized benzidine and naphthionic acid [84-86-6] (4-arnino-l-naphthalenesulfonic acid), was the precursor of a most important line of dyes, including all shades, derived from benzidine and its homologues. Today, no benzidine dye is produced because benzidine is carcinogenic. 

Direct Blue 218 had reported sales of 623 t valued at 4.4 million ia 1987. It is produced from Direct Blue 15 (76) by metallizing and elimination of methyl groups from the methoxide to form the copper complex. Direct Blue 15 (76) is prepared by coupling o-dianisidine [119-90-4] to two moles of H-acid (4-amiQO-5-hydroxy-2,7-naphthalenedisulfonic acid) under alkaline pH conditions. Other important direct blues iaclude Direct Blue 80 (74), (9-dianisidine coupled to two moles of R-acid (3-hydroxy-2,7-naphthalenedisulfonic acid [148-75-4]) followed by metallizing to form a bis copper complex, and Direct Blue 22 (77), an asymmetrical disazo dye, prepared by coupling o-dianisidine to Chicago acid [82-47-3] and 2-naphthol. Direct Blue 75 (78) is an example of a trisazo dye represented as metanilic acid — 1,6-Q.eve s acid — 1,6-Q.eve s acid — (alb) Ai-phenyl J-acid. 

Direct Black 22 [6473-13-8] (84) (Cl 35435) is produced first by coupling 4,4 dianainodiphenylainine-2-sulfonic acid to two moles of gamma acid to form a primary disazo dye, which is then bisdiazotized and coupled to two moles of y -phenylenediartiine (MPD). 

Blown and black dyes are generally disazo with exceptions for metallized or polycyclic stmctuies (7). Two disazo dyes are Reactive Brown 11 [70161-17-0] (26) and Reactive Black 5 [17095-24-8] Cl 20505) (27). 

It is especially important to control the acidity when aromatic diamines are treated with nitrous acid to form either the mono or bis diazonium salts, a process of some importance in the synthesis of disazo dyes and pigments (see later). p-Phenylenediamine is an example of a... 

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. 

The sensor for the measurement of high levels of CO2 in gas phase was developed, as well90. It was based on fluorescence resonance energy transfer between 0 long-lifetime ruthenium polypyridyl complex and the pH-active disazo dye Sudan III. The donor luminophore and the acceptor dye were both immobilized in a hydrophobic silica sol-gel/ethyl cellulose hybrid matrix. The sensor exhibited a fast and reversible response to carbon dioxide over a wide range of concentrations. 

Soares GMB, Amorim MTP, Hrdina R, Costa-Ferreira M (2002) Studies on the biotransformation of novel disazo dyes by laccase. Process Biochem 37 581-587... 

Schliephake K, Mainwaring DE, Lonergan GT, Jones KI, Baker WL (2000) Transformation and degradation of the disazo dye Chicago sky blue by a purified laccase from Pycnoporus cinnabarinus. Enzyme Microb Biotechnol 27 100-107... 

Disazo Condensation Red, pigment for plastics, 7 366t, 367t Disazo Condensation Yellow, pigment for plastics, 7 366t, 366t Disazo dyes, 9 249, 393... 

The ability to adopt an extended configuration has been recognised for many years to be a desirable feature of substantive dyes. It helps to explain why J acid is such a popular choice as a central component in unsymmetrical disazo dyes. For example, it is much easier for aniline—>] acid—>H acid (3.61) with the 2,6-naphthylene substitution pattern to adopt a linear conformation than for the similar disazo dyes aniline—acid— H acid (3.62) and aniline—>H acid—>J acid (3.63) with 2,7- and 2,8-disubstitution respectively. 

Table 3.8 Substantivity of symmetrical disazo dyes derived from naphthylamine monosulphonic acids [70]...

A full interpretation of the relationships between direct or vat dye structure and substantivity for cellulose must take into account the contribution of multilayer adsorption of dye molecules within the pore structure of the fibre [71]. The great difference in substantivity between Cl Direct Red 28 (3.66) and the monoazo acid dye (3.67) that is the half-size analogue of this symmetrical disazo dye may be interpreted in terms of their relative tendencies to form multilayers within the fibre pores as a result of dye-dye aggregation. Saturation adsorption values of these two dyes on viscose fibres at pH 9 and 50 °C corresponded to monolayer coverage areas of approximately 90 and 11 m2/g of internal surface respectively [72]. In view of the smaller molecular area and greater mobility of the half-size acid dye, higher uptake than the direct dye would be anticipated if there were only a limited area of internal surface available for true monolayer adsorption. 

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