Glucose in cellulose

The glucose in cellulose, however, is slightly different from the glucose in starch and glycogen. In the glucose of starch and glyco-... 

FIGURE 23.17 Both starch (a) and cellulose (b) are polymers of glucose. In starch, all the cyclic glucose units are a-D-glucose. In cellulose, all the monomer units are /3-D-glucose. 

Both cellulose and starch are polymers of glucose. In cellulose, the monomers are joined by a p-glycosidic linkage, whereas in starch they are joined by an a-glycosidic linkage. 

Figure 3.4 Reaction mechanism for Cl-oxidation of a glucose in cellulose. One ojq gen in the carbojg l group originates from molecular otygen, while the other oxygen comes from a water molecule. Two electrons and two hydrogens are consumed in the reaction.

Supercritical fluid solvents have been tested for reactive extractions of liquid and gaseous fuels from heavy oils, coal, oil shale, and biomass. In some cases the solvent participates in the reactions, as in the hydrolysis of coal and heavy oils with water. Related applications include conversion of cellulose to glucose in water, dehgnincation of wood with ammonia, and liquefaction of lignin in water. 

The most abundant organic molecule in the biosphere is cellulose, a polysaccharide that is the principal building material for plants. Like amylose, cellulose is a linear polymer of glucose. Unlike amylose, however, the glucose monomers in cellulose are in the ji configuration (see Figure IS-lSt. 

Figure 17-5. Amylose, cellulose. Amylose consists of a water-soluble portion, a linear polymer of glucose, the amylose and a water-insoluble portion, the amylopectin. The difference between amylose and cellulose is the way in which the glucose units are linked. In amylose, a-linkages are present, whereas in cellulose, p-linkages are present. Because of this difference, amylose is soluble in water and cellulose is not. Chemical modification allows cellulose to become water soluble.

A method developed in the MBR involved heating the cellulose with 1% sulfuric acid, from ambient to 215 °C within 2 min, maintaining this temperature for 30 s and cooling. The entire operation was completed within 4 min and afforded glucose in nearly 40% yield, along with fermentable oligomers [26]. 

The final product was subjected to ferric chloride-hydrochloric acid treatment in the same manner as commercial glucose and starch. A linear carbon dioxide-time relationship was observed which was practically identical with that for starch. In other words purified cotton cellulose, on relatively complete hydrolysis, appeared to give glucose in a... 

Langsford et al. reported that Cellulomonas fimi culture supernatants contained cellulase and proteinase activities, for which there appeared to be a relationship. Glucose repressed the synthesis of both activities and cellulose induced both 60), Adding cellulose to Cellulomonas sp. (NRCC 2406) cultures stimulated growth and improved production of cellulases 61). Optimum conditions for growth and cellulase production were pH 6.5 and 30 C. The addition of glucose in the presence of cellulose inhibited growth. Several species of Cellulomonas have cellobiose phosphorylase. 

Since an average of only one hydroxyl group in each repeating glucose unit in cellulose reacts with carbon disulfide, the xanthate product is said to have a degree of substitution (DS) of one out of a potential DS of three. 

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