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Mechanism of cerium (IV) oxidation of glucose and cellulose

 

作者: Charles R. Pottenger,   Donald C. Johnson,  

 

期刊: Journal of Polymer Science Part A‐1: Polymer Chemistry  (WILEY Available online 1970)
卷期: Volume 8, issue 2  

页码: 301-318

 

ISSN:0449-296X

 

年代: 1970

 

DOI:10.1002/pol.1970.150080203

 

出版商: John Wiley&Sons, Inc.

 

数据来源: WILEY

 

摘要:

AbstractCerium (IV) oxidations of model compounds for the hydroxylic functional groups of cellulose were conducted in 1.0Mperchloric acid. Glucose, the model selected for the reducing end group, was oxidized 360 times faster than Schardinger β‐dextrin, the model for anhydro‐D‐glucose repeating units. In the presence of a fourfold excess of glucose, stoichiometry indicated specific conversion to arabinose; the competitive oxidation of arabinose produced is insignificant. Specific C1–C2bond cleavage was also indicated for 2‐O‐methyl‐D‐glucose, galactose, 2‐O‐methyl‐D‐galactose, and cellobiose. Anhydro‐D‐glucose units were oxidized predominantly by C2–C3bond cleavage as shown by the identification of erythrose and glyoxal in hydrolyzates of cerium (IV) oxidized Schardinger β‐dextrin and cellulose. Kinetic studies showed that chelate complexes were involved in oxidations of glucose, methyl β‐D‐glucopyranoside, 1,5‐anhydro‐D‐glucitol, and Sahardinger β‐dextrin. The oxidations of glucose derivatives which differed with respect to substituents on C1and C2demonstrated the importance of the hemiacetal group and the presence of oxygen on C2. For example, the relative rates of oxidation at 15°C for methyl β‐D‐glucopyranoside, 1,5‐anhydro‐D‐glucitol, 2‐deoxy‐D‐glucose, glucose, and 2‐O‐methyl‐D‐glucose are 1:1:12:360:1860, respectively. The mechanism of glucose oxidation is thought to involve formation of a chelate complex, disproportionation of the complex to form a free radical at either C1or C2and further rapid oxidation to 4‐O‐formyl‐D‐arabinose which is hydrolyzed in the reaction medium. General implications of the experimental results

 

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