Triazinyl dyes

The introduction of auxochromes into the almost colorless anthraquinone permits the tailoring of compounds to cover nearly all shades of dye colors types and positions of the substituents in the molecule determine the hue. As a rule the bathochromic shift in simple anthraquinones increases with increasing basicity of the substituents. This generalization is clearly shown by the wavelengths of the longest wavelength absorption maximum of anthraquinones mono substituted in the 1-position [1] (Table 3.5)  

The wavelengths of the absorption maxima of hydroxy- and aminoanthraqui-nones are a function of position and number of OH and NH2 groups [1] (Table 3.6)  

The large shift from the 1,8- to the 1,4-disubstituted anthraquinones, which even exceeds that between the a- and the 3-substituted compounds, is remarkable. For a-substituents, additional changes in shade and color fastness occur on formation of hydrogen bonds to the neighboring carbonyl group. 

Alteration of color in isomeric compounds can be demonstrated by comparing various diaminohydroxyanthraquinones  

The effect of 3-substituents on the hue is best demonstrated by the 1,4-diami-noanthraquinones  

---

Most mono-anchor dyes are derivatives of cyanuric chloride (2,4,6-trichloro-1,3,5-triazine [108-77-0]), a molecule of wide synthetic potential because the three chlorine atoms on the triazine ring differ in their reactivities [12], The first chlorine atom exchanges with nucleophiles in water at 0 - 5 °C, the second at 35 -40 °C, and the third at 80 - 85 °C. A wide variety of triazinyl dyes can thus be prepared by careful selection of the reaction conditions. Condensation of cyanuric chloride with a chromophore ( Chrom. ) containing an amino group yields the highly reactive dichlorotriazinyl dyes 1 [11]. These very reactive dyes are sensitive to hydrolysis, and a suitable buffer is usually added to the powdered dye to increase its stability [13],... 

Triazinyl Dyes. The principle of linking two or three azo dyes by means of a tria-zine ring was established by Ciba patents [7], The triazine bridge increases the substantivity of the dyes, in a similar manner to the -NH-CO- NH- group (for synthesis see Section 3.3.4). 

Triazinyl Dyes. The synthesis is based on cyanuric chloride, the three chlorine atoms of which can be replaced in stages by nucleophilic radicals under different conditions. 

An outstandingly important property of the cyanuric chloride residue is that if one or two of the chlorine atoms are left unsubstituted they will react with the hydroxyl groups of cellulose. The reaction between a dichloro-triazinyl dye and cellulose, which takes place at 20°C (68°F), is illustrated diagrammatically below ... 

The triazinyl dyes can, at the same time, undergo hydrolysis with water to form the compound represented by (3) ... 

Procion H senes (I.C.I.) and the Cibacrons (Ciba). Triazinyl dyes containing one chlorine atom have been in use as direct dyes for many years and some are described by Fierz-David and Matter (J.S.D.C., 1937, 53, 424), such as Chlorantine Fast Blue 8G, (8), and Chlorantine Fast... 

Coupling of w-atninoalkyl-triazinyl-dyes to activated silicas... 

A feature of the chemistry of triazinyl reactive dyes, which is in fact common to all reactive dye systems, is that they undergo, to a certain extent, a hydrolysis reaction that involves reaction of the dye with OH anions present in the aqueous alkaline dyebath in competition with the dye-fibre reaction. The hydrolysis reaction is also illustrated in Scheme 8.1. Reactive dye hydrolysis is a highly undesirable feature of reactive dyeing for a variety of reasons. In the first instance, the hydrolysed dye 175b which is formed is no longer capable of reacting with the fibre and so must be washed out of the fibre after dyeing is complete, to ensure the... 

Brighteners are applied to cotton by methods similar to direct dyes. By far the most common are triazinyl derivatives of diaminostilbenedisulphonic acid (DAS) of general formula 11.5, where M is an alkali metal, ammonium or alkylammonium cation. Examples of groups Ilj and R2 are shown in Table 11.1. Most suppliers of FBAs market such compounds, often called DAST brighteners. Products in this class have sometimes been marketed because the supplier needed to offer something different for commercial reasons, or to avoid infringing a competitor s patent, rather than for any real technological necessity. 

Warm- and cold-dyeing double-anchor dyes are prepared by incorporating halo-triazinyl and vinylsulfonyl reactive anchors. The bond between the triazine ring and a fiber is stable under basic conditions, whereas that to the vinylsulfonyl group is stable to acid. A combination of the two anchor systems therefore produces a dye with... 

Despite the growing importance of mixed reactive systems, only the mono-chloro-triazinyl/vinylsulfonyl and monofluorotriazinyl/vinylsulfonyl dyes described above have become commercially established. 

Conventional directdyes include monoazo, disazo. trisazo. and tetrakisazo dyes. It is advantageous to subdivide them according to the nature of their chemical structure. Disazo dyes, for example, can be divided according to chemical synthesis principles into primary and secondary. Conventional azo direct dyes further include symmetric urea derivatives, dyes obtained by oxidation of amines, and triazinyl and copper-containing dyes. 

The structure of Blue Dextran 2000, a water-soluble commercial derivative, involves a triazine type of dye covalently linked to dextran, and, in a way analogous to that used for other dyed polysaccharides, has been employed for the assay of dextranase. The ability of Blue Dextran 2000 to bind proteins cannot be attributed to formation of a covalent link, because no chloro groups remain on the triazinyl rings. The binding must involve an ionic bond between the protein and the sulfonic groups of the dye residue, and, in one case, the association could be reversed by using 0-(2-diethylaminoethyl) cellulose to abstract the dyed polysaccharide. Other chlorotriazinyl dyes have been used in the preparation of dyed derivatives of amylopectin, laminaran, dextrans, pectin, pelvetian, zosterine, and cellulose. As already mentioned, triazine-dyed polysaccharides are useful in enzyme insolubilization. 

An advance was made in 1934 by CIBA in introducing the Chlorantine Greens formed by linking a blue anthraquinone dye and a yellow azo dye by means of a substituted triazinyl ring system (Figure 2.28). 

---