Cellulose oxidation with nitrogen dioxide

Formazan of Cellulose Oxidized with Nitrogen Dioxide... 

Full oxidation of monosaccharides by nitric acid to aldaric acids has been an established technique for more than a century. Analogously, oxidation of polysaccharides such as cellulose or starch by nitrogen dioxide (N2O4) yields 6-carboxy starch and 6-carboxycellulose respectively [84]. Subsequent hydrolysis at rigorous conditions (0.5-2M HCl at 150°C) of these materials yields D-glucuronic acid. A drawback of the oxidation with nitrogen dioxide is that depolymerisation may be an important side reaction. An improvement of the process with respect to this aspect can be achieved by conducting the reaction when the polysaccharide is dissolved In 85% phosphoric acid and with sodium nitrite as the oxidant better yield versus a more Important depolymerisation [85-86]. 

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. 

Kenyon and coworkers17 much information concerning the preparation and properties of the product of oxidation of cellulose with nitrogen dioxide has been elaborated. This oxidation has been shown to occur with the initial rapid incorporation of nitrogen by the cellulose followed by a slower loss.174 This is interpreted as an initial nitration followed... 

Yackel and Kenyon and Maurer and Reiff were the first to oxidize cellulose with nitrogen dioxide to obtain a poly(glycosiduronic acid). In addition to the principal reaction, their investigations pointed to the possibility of a number of side reactions. The formazan reaction revealed the presence of aldehyde groups in cellulose wads transformed to... 

Oxidized Cellulose. Absorbable cellulose ceilu-losic acid polyanhydroglucuronic acid Oxycel Hemo-Pak. A cellulose of varied carboxyl content retaining the fibrous structure. Frepd by oxidizing cellulose with nitrogen dioxide Yack el. Kenyon, J. Am. Chem. Soc. 64, 121 (1942). 

The main reaction path of cellulose with nitrogen dioxide gas or solution is the oxidation of the C-6 primary hydroxyl group of the anhydroglucose unit to carboxylic acid. Several schemes proposed to describe this reaction are based on the hypothesis that nitrites of cellulose form as intermediates and subsequently take part in the oxidation process. 

Synonyms Cellulose, oxidized Cellulosic acid Oxycellulose Definition Cellulose produced by treatment with nitrogen dioxide Properties SI. of-wh. gauze, lint, or powd. si. charred odor acid taste sol. in aq. org. bases, dll. alkali, ammonium hydroxide insol. in water, acids, common org. sol vs. 

Shoryghin and Khait [57] brought cellulose into contact with vapours of nitrogen dioxide at room temperature and obtained a product largely oxidized and degraded, that contained up to 3.2% N. 

The use of nitrogen dioxide for the selective oxidation of polysaccharides to polyuronic acids was introduced by Kenyon and his coworkers13,63 in 1941. By this means extensive oxidation of the primary alcohol groups in cellulose was obtained, through the mechanism of preferential nitration followed by decomposition of the nitric acid ester with carboxyl forma-tion.68(0< > Apparently some undissociated nitration products also were formed, since infrared absorption studies54 indicated the presence of nitrate radicals in the polyuronic acid. Side reactions produced carboxyl,... 

The affinity of variously oxidized cellulosic materials for certain basic dyes, notably methylene blue, has long been known. Kenyon and coworkers have recently shown that in the case of nitrogen dioxide oxycelluloses, the methylene blue absorption is a function of the carboxyl group content. Application of the reversible methylene blue method to the determination of carboxyl groups in purified cellulose has been made by Davidson and by Weber, who was able to show good agreement with the cation-exchange methods previously considered as well as with viscosity and osmotic pressure measurements. 

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