Fibre-reactive groups

Fibre-reactive Groups Reacting by Nucleophilic Substitution... 

By far the most important fibre-reactive groups which react by nucleophilic substitution contain six-membered aromatic nitrogen-containing heterocyclic rings with halogen substituents. The first group of com-... 

The initial success of the reactive dyes based on the triazine ring system was immediately followed by intense research activity into the possibilities offered by other related nitrogen-containing heterocyclic systems. Numerous systems have been patented as fibre-reactive groups although only a few of these have enjoyed significant commercial success. Some examples are illustrated in Figure 8.2. They include the trichloro-pyrimidines 176, the dichloropyridazines 177, the dichloroquinoxalines 178 and the chlorobenzothiazolyl dyes 179. 

There is no doubt that the major weakness of the reactive dyeing process is the hydrolysis reaction and the consequent need for a wash-off" process. The extent to which dye hydrolysis takes place in competition with dye-fibre reaction varies quite markedly within the range 10 40% depending upon the system in question. A considerable amount of research has therefore been devoted to the search for reactive dyes with improved fixation. The most successful approach to addressing this issue has involved the development of dyes with more than one fibre-reactive group in the molecule, which statistically improves the chances of dye fibre bond formation. Examples of products of this type are the Procion H-E... 

Lim, S. H., and Hudson, S. M. (2004). Synthesis and antimicrobial activity of a water-soluble chitosan derivative with a fibre-reactive group. Cgrbghyjj, 339, 313-319. 

Fibre-Reactive Groups Reacting by Nucleophilic Addition... 

The most important reactive dyes in commercial use for application to cellulosic fibres in which the fibre-reactive groups react by nucleophilic addition are the Remazol reactive dyes. These dyes, based on the vinylsulfone reactive group, were introduced by Hoechst soon after the launch of the Procion dyes based on the triazine system by The chemistry of the process in which vinylsulfone... 

A selection of representative chemical structures from the vast range of reactive dyes now available commercially is illustrated in Figure 8.5. Reactive dyes may be prepared, in principle, from any of the chemical classes of colorant by attaching a fibre-reactive group to an appropriate molecule. In common with most application classes of textile dyes and pigments, most reactive dyes belong to the azo chemical class, especially in the yellow, orange and red shade areas. Examples are typified by the structurally related red monoazo reactive dyes, the dichlorotriazine 8.28a, Cl Reactive Red 1, the... 

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