Anhydroglucose residues

Etherification. The accessible, available hydroxyl groups on the 2, 3, and 6 positions of the anhydroglucose residue are quite reactive (40) and provide sites for much of the current modification of cotton ceUulose to impart special or value-added properties. The two most common classes into which modifications fall include etherification and esterification of the cotton ceUulose hydroxyls as weU as addition reactions with certain unsaturated compounds to produce ceUulose ethers (see Cellulose, ethers). One large class of ceUulose-reactive dyestuffs in commercial use attaches to the ceUulose through an alkaH-catalyzed etherification by nucleophilic attack of the chlorotriazine moiety of the dyestuff ... 

Hydroxyethyl starch (HES) is a derivative of the highly branched starch, amylopectin, in which the anhydroglucose residues are substituted by hydroxyethyl groups to reduce metabolic degradation by plasma a-amylase. The... 

Carbamovlethvlation and CarbQxvethvlation. The purified cotton fibers were carbamoylethylated and carboxyethylated in aqueous solution containing acrylamide and 20 sodium hydroxide for lOh at 20 C. Then the samples were washed with distilled water, 0.1 acetic acid, and distilled water and air-dried. Degree of carbamoylethylation and carboxyethylation per anhydroglucose residue of the samples was determined by micro Kjeldahl method and back-titration technique (l), respectively. 

In assessing the stability of intermolecular hydrogen bonds, the pattern of chemical reactivity of the hydroxyl groups may be an indicator. On the basis of the results of relative reactivities of the hydroxyl groups in the anhydroglucose residues, the more stable Intermolecular hydrogen bonds of cellulose appear likely to involve 6-OH, because it often shows lower reactivity for etherifications than the 2-OH. 

Fig. 4. Solubility of azobenzene in Sephadex G-10 and dextran solution in 0.1 M NaCI relative to that in 0.1 M NaCl plotted against anhydroglucose residue concentration. (Based on data from Janado et al. (ref. 59,86).)...

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