Metallized Azo Dyes

The three metals of importance in azo dyes are copper, chromium, and cobalt. The most important copper dyes are the 1 1 planar copper(n) azo dye complexes (74). 

In contrast, chromium(m) and cobalt(m) form 2 1 dye metal complexes that have nonplanar structures. Geometrical isomerism exists. The o.o -dihvdroxyazo dyes (75) form the Drew-Pfitzner or mer type (76) (A = C = O), whereas o-hydroxy-o -carboxyazo dyes (77) form the Pfeififer-Schetty or fac type (78) (A = CO 2 and C = O). 

Metallization of dyes was originally carried out during the mordanting process to help fix the dye to substrate. Premetallized dyes are now used widely in various 

These dyes are the backbone of most commercial dye ranges. Based entirely on benzene and naphthalene derivatives, they provide yellow, red, blue, green, and black colors for all the major substrates such as polyester, cellulose, nylon, polyacrylonitrile, and leather. Typical structures are (79)—(84). 

Disperse Yellow 3 (79) is used to dye polyester C.I. Reactive Orange 1 (80) is a cotton dye C.I. Direct Orange 26 (81) is a dye for paper C.I. Basic Red 33 (82) dyes acrylic fibres C.I. Acid Red 38 (83) dyes nylon and wool C.I. Reactive Black 5 (84) dyes cotton. 

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The condensation on the fabric of 1-amino-3-iminoisoindo1enines or 2-amino-5-iminopyrro1enines with phloroglucinol, preferably in the presence of metal salts and solvents, yields fast dyeings in brown shades (158). Metallized azo dyes derived from phloroglucinol yield fast dyeings on leather (qv) or silk (qv) (159). 

Metallization of dyes was originally carried out during the mordanting process to help fix the dye to the substrate. Premetallized dyes ate now used widely in various oudets to improve the properties of the dye, particularly lightfastness. However, this is at the expense of brightness, since metallized azo dyes are duller than nonmetallized dyes. 

Metallized azo dyes, 9 250-251 Metallized dye developers, 19 286 Metallized dyes, stability of, 19 296 Metallizing, ABS, 1 428. See also Metalbzation... 

The application of isosterism for the design of safer commercial chemicals is much less common than it is for the design of safer drugs or pesticides. There are some examples, however, of how isosterism has been used to design safer commercial chemical substances. One very successful application is in the case of metallized azo dyes [82, 83]. Historically, chromium was a metal of choice in many metallized azo dyes because it imparts the desired color and fastness. Hexavalent chromium (Cr6+) was often used in making such dyes. 

Some coordination compounds have been used as dyes and pigments, but it must be admitted that these applications developed without reference to the fact that the compounds are complexes. Examples of paint pigments are Prussian blue and the phthalocyanines metallized azo dyes are common in the textile industry. 

Aminonaphthols and Aminonaphtholsiillonic Acids The aminonaphthols are of minor use but the aimnohydroxynaphthalene-sulfonic acids are intermediates for dyes, e.g., fiber-reactive azo dyes and plain and metallized azo dyes (Table 7). A number of A -acyl-, V-alkyl-, and V-arylaminonaphthaleneosulfonic adds arc used as couplers for azo dyes. 

Coplanarity in 2,6-dimethylazobenzenes56 and its effect on the efficiency of transmission of electronic effects from one ring to the other was studied by Byrne and Happer using 13C chemical shifts. The methyl groups have a substantial effect on the planarity of the system, but, surprisingly, a loss of planarity has relatively little effect on the efficiency of transmission of both polar and resonance effects between the two rings. H and 13C NMR studies of substituent effects on the molecular planarity was performed by Koleva et al.51 Jirman58 was interested in H and 13C NMR spectra (Tables 5 and 6) of 2,2 -disubstituted azobenzenes (16) and 2,2 -azopyridine (17) suitable for preparation of metallized azo dyes. 

Pre-metallized azo dyes were introduced shortly before World War I, and shortly before World War II metallized wool dyes, known commercially as Neolan and Palatin, came on the market. They were completely metallized azo dyes with shades ranging from yellow to black and were coordinated complexes of chromium. Three examples include (35) ... 

Metallized Azo Dyes this group of azo dyes usually composed of a chromium or cobalt ions. The colour produced is dependent on the combination of a metal ion with a ligand which may be a constituent of the azo group itself or a substituent such as -... 

Metallized azo dyes are utilized for their brightness and clarity of color. Complexed with either chrome or cobalt these dyes have been used in styrene and acrylic. They have some enhanced heat and light stability over the standard azo dyes. Solvent Yellow 82 is a commonly used dye of this type. 

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