Chemical changes produces in the cellulose macromolecule by oxidizing agents

Autor: E. D. Kaverzneva, Z. I. Kuznetsova, V. I. Ivanov
Rok vydání: 1954
Předmět:
Zdroj: Bulletin of the Academy of Sciences of the USSR Division of Chemical Science. 2:341-350
ISSN: 1573-9171
0568-5230
DOI: 10.1007/bf01171007
Popis: 1. A study has been made of the composition of oxycelluloses obtained by oxidation with hydrogen peroxide in acid, neutral, and alkaline media. 2. It has been shown that chemical modification of the cellulose and fall in degrees of polymerization occurs at all values of pH, though in varying degree: oxidation proceeds most intensively in strongly alkaline (pH 4) media. 3. In the oxidation of cellulose by hydrogen peroxide the same chemical processes occur as in the oxidation of the simplest sugars, namely: the primary OH groups are oxidized to aldehyde and carboxyl groups; secondary OH groups are oxidized with formation of ketone groups and oxidation of 2,3-glycol groupings with rupture of the ring yielding two aldehyde groups, which may be converted further to carboxyls. The introduction of a catalyst(Fe++) accelerate the oxidation processes, particularly those leading to rupture of the pyran ring with formation of nonuronic carboxyls. 4. Certain differences are to be observed between the chemical composition and properties of oxycelluloses obtained by hypochlorite and by peroxide oxidation. The most important cause of these appears to be the breakdown of the glycol groupings into two aldehyde groups, a reaction that has not yet been shown to occur in oxidation with hypochlorites. 5. Owing to the occurrence to a marked extent of the latter type of oxidation with rupture of the pyran ring, the variety of new functional groups formed in the cellulose macromolecule during its oxidation by hydrogen peroxide is even greater than in hypochlorite oxidation: under all pH conditions groups will be formed that reduce the stability of the glucoside linkages in acid and alkaline media and so induce chain-breakdown.
Databáze: OpenAIRE
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