Direct blue dyes

H-acid, l-hydroxy-3,6,8-ttisulfonic acid, which is one of the most important letter acids, is prepared as naphthalene is sulfonated with sulfuric acid to ttisulfonic acid. The product is then nitrated and neutralized with lime to produce the calcium salt of l-nitronaphthalene-3,6,8-ttisulfonic acid, which is then reduced to T-acid (Koch acid) with Fe and HCl modem processes use continuous catalytical hydrogenation with Ni catalyst. Hydrogenation has been performed in aqueous medium in the presence of Raney nickel or Raney Ni—Fe catalyst with a low catalyst consumption and better yield (51). Fusion of the T-acid with sodium hydroxide and neutralization with sulfuric acid yields H-acid. Azo dyes such as Direct Blue 15 [2429-74-5] (17) and Acid... 

Phthalocyanine Dyes. In addition to their use as pigments, the phthalocyanines have found widespread appHcation as dyestuffs, eg, direct and reactive dyes, water-soluble dyes with physical or chemical binding, solvent-soluble dyes with physical or chemical binding, a2o reactive dyes, a2o nonreactive dyes, sulfur dyes, and wet dyes. The first phthalocyanine dyes were used in the early 1930s to dye textiles like cotton (qv). The water-soluble forms Hke sodium salts of copper phthalocyanine disulfonic acid. Direct Blue 86 [1330-38-7] (Cl 74180), Direct Blue 87 [1330-39-8] (Cl 74200), Acid Blue 249 [36485-85-5] (Cl 74220), and their derivatives are used to dye natural and synthetic textiles (qv), paper, and leather (qv). The sodium salt of cobalt phthalocyanine, ie. Vat Blue 29 [1328-50-3] (Cl 74140) is mostly appHed to ceUulose fibers (qv). 

Stilbene dyes of importance aie mosdy direct yellow dyes for ceUulosic fibers, especially paper. There have been several red and blue stilbene-containing dyes reported, but they have not (ca 1996) been developed to commercial importance. There are brown leather dyes which are stilbene-based. The most important stilbene dyes are those known siace the 1880s. The commercial importance of Direct Yellow 11 (1883), Direct Orange 15 (1888), Direct Yellow 4 (1886), and Direct Yellow 106 (1936) attest to the value, properties, and durabiUty of stilbene yellow dyes. 

Direct Blues. Direct Blue 86, a phthalocyanine direct dye, represents a small but important segment of the direct dye stmcture groups. The dyes are brilliant greenish blue or turquoise shades. Sales of nearly 2 million were reported in the United States in 1988. Among the disazo blues. Direct Blue 80 (74) and Direct Blue 98 (75) were sold in 152 t and 107 t quantities at an average cost of 2.22 and 1.81/kg, respectively, in 1988. Table 7 and Figure 6 show some direct blues. 

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. 

Of all the metal complexes evaluated, copper phthalocyanines give the best combination of color and properties and consequentiy the majority of phthalocyanine dyes are based on copper phthalocyanine Cl Direct Blue 86 [1330-38-7] (Cl 74180) (68) is a typical dye. 

DihydroxyanthraquiQone (anthranifin) [117-12-4] (47) is an important iatermediate for manufacturiag disperse blue dyes, eg. Cl Disperse Blue 73 (113), and is prepared from anthraquiQone-l,5-disulfonic acid by heating with an aqueous suspension of calcium oxide and magnesium chloride under pressure at 200—250°C (67). Alternative methods have been proposed, ie, direct replacement of the NO2 groups of 1,5-dinitroanthraquiaone (49) (68) or the route via 1,5-dimethoxyanthraquiaone [6448-90-4] (48) and subsequent hydrolysis (69). 

Copper and chromium are used for complexing a number of dyes such as the coppered direct and reactive dyes for cotton and metaUi2ed and neutral metal complex acid dyes for nylon, wool, etc. Examples are Direct Blue 218 [28407-37-6] (Cl 24401) (317), Reactive Violet 2 [8063-57-8] (Cl 18157) (318), and Acid Black 52 [5610-64-0] (Cl 15711) (319). 

In view of the immense commercial importance of phthalocyanines as pigments, it is perhaps surprising that only a few are of importance as textile dyes. This is primarily due to the size of the molecules they are too large to allow penetration into many fibres, especially the synthetic fibres polyester and polyacrylonitrile. An example of a phthalocyanine dye which may be used to dye cellulosic substrates such as cotton and paper is C. I. Direct Blue 86 (96), a disulfonated copper phthalocyanine. In addition, a few blue reactive dyes for cotton incorporate the copper phthalocyanine system as the chromophoric unit (Chapter 8). 

El-Bahy ZM, Ismail AA, Mohamed RM (2009) Enhancement of titania by doping rare earth for photodegradation of organic dye (Direct Blue). J Hazard Mater 166 138-143... 

Figure 12.4 Equilibrium absorption isotherms at 34 °C and rate of dyeing curves at 40 °C for Cl Direct Blue 1 on viscose in the presence of electrolytes singly and in binary mixtures [70]...

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. 

Water-soluble phthalocyanine dyes may contain only sulfonic acid groups but normally contain both sulfonic acid and sulfonamido groups. They are used as direct dyes for paper and as reactive dyes for cotton. Representative examples are Cl Direct Blue 199 (38) and Cl Reactive Blue 71 (39). These dyes are also used for the ink jet printing of textiles (see Section 9.12.6.2). 

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 desmolyticum Direct Blue 6, Green HE4B, Red HE7B The dye GHE4B was completely decolorized in 12 h while DB 6 and RHE7B were decolorized in 16 h [80]... 

Procion navy blue, Procion green, Direct blue, and a mixture of azo dyes Consortium comprised of three bacterial strains A high efficiency for dye degradation was observed even at high dye concentrations [159]... 

Kalme SD, Parshetti GK, Jadhav SU, Govindwar SP (2007) Biodegradation of benzidine based dye Direct Blue-6 by Pseudomonas desmolyticum NCIM 2112. Bioresour Technol 98 1405-1410... 

A striking feature of disperse dye development in recent decades has been the steady growth in bathochromic azo blue dyes to replace the tinctorially weaker and more costly anthraquinone blues. One approach is represented by heavily nuclei-substituted derivatives of N,N-disubstituted 4-aminoazobenzenes, in which electron donor groups (e.g. 2-acylamino-5-alkoxy) are introduced into the aniline coupler residue and acceptor groups (acetyl, cyano or nitro) into the 2,4,6-positions of the diazo component. A PPP-MO study of the mobility of substituent configurations in such systems demonstrated that coplanarity of the two aryl rings could only be maintained if at least one of the 2,6-substituents was cyano. Thus much commercial research effort was directed towards these more bathochromic o-cyano-substituted dyes. 

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