Chlorotriazinyl dyes

The instability of the solutions of the cold-dyeing Procion colours was a serious disadvantage in their application to textile printing. The stock solution for printing must be kept and used for several hours. The mono-chlorotriazinyl dyes of the general structure of formula (7) are less reactive. 

The method of application is basically similar to the chlorotriazinyl dyes. The dyebath is made up with SO to 100 g per litre of common salt and fixation is brought about by the addition of 30 to 40 g per litre of soda ash, 20 to 30 g per litre of trisodium phosphate or 1-5 to 7 ml of sodium hydroxide (66°Tw 23 per cent). The temperature necessary for fixation varies from 80 C (176°F) to 90°C (198°F) according to the dye and the method of application. When these dyes are applied in a winch or a package machine the dye, salt, and alkali can all be added at the commencement because there is little danger of the reactive group becoming hydrolysed before it has reacted with the cellulose. The trichloropyrimidyl dyes do not exhaust easily and padding methods are therefore preferable. 

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. 

Reactone dyes, which contain trichloropyrimidinyl groups, react with polysaccharides in an analogous way to chlorotriazinyl dyes, but the extent of reaction is somewhat less, at least in their reaction with cellulose. Reactone Red 2B derivatives of amylose, amylopectin, " starch, and barley )8-glucan provide substrates for amylases and y3-glucanases in the assay of these enzymes. 

Trichloropyrimidinyl and chlorotriazinyl dye derivatives of polysaccharides are considered to be more satisfactory than Ramazol dye derivatives, the ether linkage being considered the weakest of those present. The dyeing of polysaccharides has been advocated as an aid to their identification in gel electrophoresis, gel filtration, and cellulose acetate electrophoresis, although it must be borne in mind that such deriva-tizations alter the characteristics of the polysaccharide under examination. 

The usefulness of these chlorotriazinyl dyes in binding to textiles had been recognized in the 1950 s. However, optimal binding procedures of these dyes to polysaccharide matrices were developed more recently.The application of dye - ligand chromatography to protein purification has been reviewed recently. ... 

Follow the procedure given in Section 4.1.1 using amino-silica (see Section 3.3) and any chlorotriazinyl-dye. The concentration of inunobilized ligand could be up to 25 /imol/g diy gel. 

Reactive dyes typically contain the chlorotriazinyl group. The chloro substituent can be displaced by hydroxy functional groups from cellulosic fibres thereby incorporating the dye molecule into the fabric. Bright and lightfast colors are obtained by this approach. Reactive dyes for cotton generally contain a number of sulfonic groups to provide the water solubility which is required to apply the dyes from aqueous solutions. 

Heterocyclic halogen-containing groups other than dichlorotriazinyl and chlorotriazinyl have been used in the preparation of reactive dyes. The Reactone and Drimarine colours are substitution products of tetrachloro-pyrimidine, (9), and therefore contain a trichloropyrimidyl group in the molecule, (10). An example of such a dyestuff is Reactone Red 2B, (11). 

The choice, until recently, has been between a disperse dye with wetfastness which is not all that could be desired, accompanied by coverage of yarn variations, and faster colours which show up differences in physical and chemical properties of the polymer. When, in 1959, I.C.I. placed the Procinyl dyes on the market an advance of considerable importance was made. They are reactive dyes based on disperse dyestuff molecules containing chlorotriazinyl groups. Under neutral conditions the pattern of behaviour is that of a disperse dye and yarn irregularities are covered up to a great extent. When alkali is added to the dyebath, fixation takes place, giving wet-fastness of a high order. 

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