Cellulose Chloro group

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. 

Another early used derivative is cellulose bromoacetate (36), the bromo group of which can become displaced, for example, by a free amino group of the enzyme, as in 37. Cellulose chloro- and iodo-acetates have also been employed, and preliminary results suggest that greater enzymic activities can be obtained with the latter. ... 

Figure 15. The value of the pitch P as a function of temperature for LC (acetyl)ethyl cellulose/chloro-form (45 wt%, DS of ethyl groups 2.5). The filled and unfilled symbols represent the samples with acetyl DS below and over the compensation of the twist (0.19), respectively. Acetyl DS = 0.05 , 0.06 O, 0.08 A, 0.30 , 0.42 , and 0.50 (adapted from [1]).

Scheme 7.19), leading to dyes with a 5-chloro-4-methyl-2-methylsulphonylpyrimidine reactive system (7.24). During reaction with the cellulosic fibre under alkaline conditions, the methylsulphonyl moiety is a particularly effective leaving group and rapid fixation takes place when the reactive system approaches the cellulosate anion. 

The introduction of Calcobond dyes a few years later by American Cyanamid exploited a similar principle but incorporated the N-methylol groups into the dye molecule itself [132]. The labile chloro substituents in dichlorotriazine dyes were converted to amino groups by substitution with ammonia and the resulting melamine residue made cellulose-reactive again by reaction with formaldehyde (Scheme 7.59). A typical member of this range was Cl Reactive Red 92 (7.120). A characteristic problem of the Procion Resin process and of the... 

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. 

Although cyclic and acyclic carbonates of monosaccharides have been known for some time, little interest had been taken in such derivatives of polysaccharides, probably because the conditions could not be controlled to give any degree of specificity. The formation of cyclic carbonate rings involves treatment of the polysaccharide with ethyl chloro-formate heterogeneous reactions occur, and acyclic carbonate (ethy-oxycarbonyl) groups are also formed. The reaction conditions suitable for maximum cyclic carbonate and minimum acyclic substitution have been investigated in detail for cellulose. Other chloroformates have... 

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