Cellulose oxidized

Amines can give rise to chloramines during hypochlorite bleaching (Scheme 10.83). In addition to increasing AOX values, this can result in cellulose oxidative degradation by hypochlorite on subsequent hydrolysis of the chloramines (Scheme 10.84) [448]. 

Dinitrobenzenes Dinitrotoluenes 1,4-Dioxane Esters Ethylamine Ethers Ethylene Nitric acid Nitric acid Silver perchlorate Nitrates Cellulose, oxidizers Oxidizing materials, boron triiodide Aluminum trichloride, carbon tetrachloride, chlorine, nitrogen oxides, tetrafluo-roethylene... 

Oxidized cellulose Oxidized cellulose is a surgical gauze treated with nitrogen dioxide. Upon contact with tissue fluids, it forms artificial clots, which support mechanical hanostasis. 

The degree of cellulose oxidation decreases markedly as the concentration of N204 in the solution decreases. The nitrogen content, on the contrary, rises slightly as a result of the initial dilution, remaining constant during further decrease in concentration. 

Cellulose oxidized by means of dinitrogen tetroxide can have surgical applications as a material for dressing wounds, since it is assimilated by the human body (Kenyon et al. [58]). 

Celluloses oxidized to an aldehyde at C6 are found for instance as intermediates of the TEMPO oxidation [50]. Depending on the reaction conditions a large number of such groups may survive in the final products, the poly-glucuronic acids, and also in partially TEMPO-oxidized pulps materials it is highly likely that a large number of carbonyl groups are present as C6-aldehyde. 

While some of the above can occur with cellulose treated with the alkaline earth hydroxides or carbonates, their tendency to insolubilize compounds with carboxyl groups will work against swelling and the increase in accessibility. For example, cellulose oxidized with N204 swells and dissolves in sodium hydroxide but is not soluble in lime solution. 

When cellulose is exposed to the unlimited supply of oxygen present as 21% of the air, unstable peroxide radicals form. In the autocatalytic reaction of cellulose oxidation, decomposition of peroxide forms cellulose radicals that react with oxygen to form R02- radicals. These radicals attack other cellulose molecules to form oxycelluloses (carbonyl, aldehyde, and carboxyl acid groups) along with more cellulose free radicals (34). 

Heat catalyzes free radical formation in cellulose. Aldehydes form from C2 and C3 hydroxyls. Aldehydes oxidize to carboxyls, and with dehydration, carbon monoxide (CO) and carbon dioxide (C02) form as well as conjugated carbonyl-ethylenic chromophoric groups that selectively absorb blue light and impart yellowness (35). During the induction stage of cellulose oxidation, yellowness may increase steadily with selective carbonyl and ethylene group formation. By artificially aging... 

Both natural and forced-convection oven types can be employed they have been described in the section on drying. The forced-convection oven offers the advantages of uniformity of heat distribution and reduction in lag time in comparison with the natural-convection system. The dry-heat method is reserved almost exclusively for glass or metal as other materials char (cellulose), oxidize (rubber), or melt (plastic) at these temperatures. 

Although white-rot fungi also secrete H2O2 (104), they have not been found to depolymerize cellulose oxidatively. One reason might be that they possess oxalate decarboxylase, which decomposes oxalate, whereas brown-rot fungi apparently do not (98). This problem deserves further investigation. 

Formazan of Cellulose Oxidized with Nitrogen Dioxide... 

In 1873, it was first reported that cellulose that has been oxidized with chromic acid or potassium permanganate is weakened in alkaline solutions, and several years later these findings were confirmed. By 1899, it was known that cellulose that had been oxidized with nitric acid, or bromine in the presence of calcium carbonate, afforded oxidized celluloses from which D-glucoisosaccharinates were formed on suitable treatment with lime-water.Hydrocelluloses, alkaline-hypobromite oxycelluloses, and alkaline-hypochlorite oxycelluloses have no internal, alkali-sensitive links. Cellulose oxidized with neutral hypochlorite, acidic hypochlorite, potassium dichromate and sulfuric acid, potassium dichromate and oxalic acid, periodic acid, or metaperiodate gives products which are alkali-sensitive. Periodic acid oxycellulose and metaperiodate oxycellulose are much more alkali-sensitive than the others. ... 

Cellulose, oxidized with nitric acid, yields isosaccharinates and dihy-droxybutanoates when the product is treated with lime-water. Cellulose which has been oxidized with acidic potassium permanganate solution contains some uronic acid groups, and, when placed in dilute alkaline solutions, forms chains with a degree of polymerization (D. P.) of about 90. In more concentrated alkaline solutions, the chains are shortened more, and have a D. P. of about 35. 

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