Oxidation of Disaccharides

Among these three disaccharides, beet- and cane-derived sucrose displays the highest world production, reaching the amount of over 175 million metric tons per year, with Brazil (2014 38 t/year) and India (2014 27 t/year) being the leading producers. Compared with sucrose, lactose (1.2 million tons per year) and maltose (0.6 million tons per year) are produced in much smaller amounts. 

More interestingly, the chemoenzymatic oxidation can be efficiently applied to complex molecules such as water-soluble cellulose, thus justifying further scientific interest and developments. 

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In the a approach by Mombarg et a/.,[59] oxidation of disaccharides, such as trehalose and sucrose (25 mmol), was performed in 25 ml of water at 70 °C, with 100 mg of Ti-MCM-41 (7.2 pmol of Ti) and 25 g of 35 wt% H2O2, at pH = 4. After 20 h of reaction, a deep oxidation is observed leading to C1-C4 mono- and dicarboxylic acids, formic acid, glycolic acid, tartronic acid and tartaric acid. The absence of selectivity is then a major drawback compared with other oxidation processes, but another drawback was identified with Ti leaching from the molecular sieve framework. 

The structures of the disaccharides and higher saccharides (obtained by partial hydrolysis of polysaccharides) can be examined by periodate or lead tetraacetate oxidation. Ahlborg studied the periodate oxidation of disaccharides and starch dextrins in 0.5 N sulfuric acid. Since the intermediate formate esters were hydrolyzed, these conditions were favorable for overoxidation. The (1 — 4)- and (1 —> 6)-linkages in the starch dextrins were each found to be associated with a characteristic consumption of oxidant. Neumtiller and Vasseur studied periodate oxidation in solutions of various acidities, from strongly acid to neutral, and showed that there were differences between different types of disaccharides. 

Some p)Tanosides can be oxidized at C3 using the bacterium Agrobacterium tumefaciens. This method has been particularly successful for oxidation of disaccharides. The conversion of sucrose into 3-keto-sucrose has been studied in detail (O Scheme 13) [118]. Lactose, maltose. 

K. Ahlborg, Oxidation of disaccharides and of dextrins by Pb(OAc)2 and HIO4. An attempt to develop a simple method of determination of the position of the glycoside bonds in various disaccharides and dextrins, Sv. Kem. Tidskr., 54 (1942) 205-217. 

The oxidation of disaccharides and trisaccharides, for example, lactose (V) to lactobionic acid (VI), has proved of value in structural studies since hydrolysis yields an aldose (VII) and an aldonic acid (VIII), the latter being... 

One notices that the data from the oxidation of melezitose by per-iodic acid confirm the pyranose structure of the D-glucose unit in turanose, and therefore also in the case of maltose, in agreement with the original assignments for both of these disaccharides from methylation studies. 

On deamination, C-substance that had been treated with alkali and phosphatase yielded the disaccharide 2-0-(2-acetamido-2-deoxy-D-galactosyl)-D-ribitol. Periodate oxidation of C-substance had revealed that the ribitol residue is substituted at 0-2 and 0-5. 

Actually, on oxidation of the carbohydrate with sodium periodate, three moles of periodate are consumed and one mole of formic acid is formed. These data agree with the assumption that the disaccharide contains a pyranose and a furanose ring. The possibility that the disaccharide is made up of glucofuranose and sorbopyranose can also be eliminated on the basis of the periodate oxidation data. Glucofuranose would contain two pairs of adjacent hydroxyls, on carbon atoms 2 and 3 and on 5 and 6, and the sorbopyranose would have three adjacent hydroxyls, on carbon atoms 3, 4 and 5. In oxidizing such a disaccharide, a total of four moles of periodate would thus be used, giving rise to one mole of formic acid. This is inconsistent with the experimental data. 

On oxidation of the phenylosotriazole derivative of the disaccharide with sodium periodate, three moles of periodate are consumed with the formation of one mole each of formic acid and formaldehyde per mole of the phenylosotriazole derivative. If the D-glucose in the u-glucopyrano-syl-L-arabinose phenylosotriazole were attached to carbon atom 4 of the L-arabinose derivative, oxidation of this compound with sodium periodate would require two moles of periodate and would liberate one mole of... 

Apart from the improvements to be geiined by attention to these factors, much better yields of disaccharides are obtained when acyclic alcoholic compounds eire used and in other modifications of usual procedures it has been recommended that mercuric oxide in the presence of small amounts of mercuric bromide acts efficiently as an acid acceptor and has the added advantage of low cost and photostability 28), German workers in particular have preferred to use trityl ethers rather than... 

Oxidation of carbohydrates is probably the most efficient heterogeneously-catalyzed process since very high yield and selectivity are reported for reactions over solid catalysts. Despite important recent advances, the conversion of carbohydrates to HMF still requires further investigations. For reactions, in water, the yield of HMF is still too low due to the significant formation of side products. Today, several procedures for the conversion of monosaccharides, disaccharides, oligosaccharides, and starch in water into high value added materials are available. With cellulose, its heterogeneously-catalyzed conversion into useful products... 

Trifluoroacetic acid is volatile, and thus readily removed. This acid was used by Albersheim and coworkers for the hydrolysis of plant cell-walls,39 and has since been employed for cell walls,40-43 plant mucilages,44 blood-group oligosaccharides,45 peptidogalactoman-nans,46 heparin,47 and disaccharides in blood and urine.48,49 It has also been suggested as an alternative to 6 M hydrochloric acid in the determination of amino sugars,50 and for the hydrolysis of polyalcohols produced by periodate oxidation of polysaccharides.503 Lee... 

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