Oxidation of D-fructose

The oxidation of D-fructose with cerium(IV) in sulfuric acid medium is inhibited by an increase in the acidity. A cationic surfactant, CTAB, catalyses the reaction, whereas SDS has no effect. The catalytic role of CTAB has been explained using the pseudophase model of Menger and Portnoy. A mechanism involving the formation of an intermediate complex between /3-D-fructopyranose and Ce(S04)32- has been proposed.61 The oxidation of cycloalkanones with cerium(IV) in sulfuric acid medium showed a negligible effect of acidity. Formation of an intermediate complex, which decomposes in the rate-determining step, has been suggested.62... 

In ammoniacal solutions of copper salts, the oxidation products are likely to contain nitrogen thus, hexoses give oxalic acid, imidazoles, hydrogen cyanide, and urea. Kinetic studies have been reported for the reaction of Cu(II) in the presence of ammonia with maltose, lactose, melibiose, and cellobiose.190 For the oxidation by tetraamminecopper(II) in ammoniacal and buffered media the rate of reaction is first order in disaccharide concentration, order one-half in ammonia concentration, but it is independent of Cu(II) concentration. The reaction rate is decreased by the addition of ammonium chloride, because of the common ion effect. These kinetics suggested mechanisms involving an intermediate enediolate ion, with the rate of reaction being equal to the rate of enolization.191 A similar mechanism has been proposed for the oxidation of D-fructose by a copper-pyridine complex in an excess of pyridine.192... 

A. K. Singh, A. K. Sisodia, A. Parmar, M. Saxena, and P. S. Bajpai, Spectrophotometric studies in kinetics and mechanism of oxidation of D-fructose by GhCsHsN) in presence of free pyridine, Natl. Acad. Sci. Lett. (India), 9 (1986) 309-312 Chem. Abstr., 107 (1987) 96992. 

The kinetics of oxidation of D-fructose and D-glucose in aqueous alkaline medium with nine sodium salts of mono- and di-substituted A-chloroarylsulfonamides have been determined. The Hammett reaction constants, p, for the oxidation of glucose and fructose are 0.28 and 0.54, respectively. The results have been explained by a plausible mechanism, and the related rate laws have been deduced.108... 

Attempts by Smith and ToUens " to oxidize n-fructose with bromine by the method of Clowes and Tollens were unsuccessful a double compound of D-fructose and calcium bromide was obtained. No yield of this product was given. The reaction mixture of D-fructose, calcium carbonate, water and bromine was shaken until all the bromine had dissolved, after which the double compound was separated from the concentrated solution. The calcium bromide was formed from the interaction of calcium carbonate with hydrogen bromide in the reaction solution. The hydrogen bromide could be formed in two ways by the hydrolysis of bromine in water (reaction 1, page 134) or by the reduction of bromine during the oxidation of D-fructose. The former is the more probable explanation, but a blank run without the ketose was not attempted. 

Synthesis from o-fructose D-Fructose has been used for the synthesis of 2R,5S-dihydroxymethyl-31 ,47 -dihydroxypyrrolidine (3) and its analogues (Scheme 4). Thus, microbial oxidation of D-fructose led to 5-keto-D-fructose (24), which was condensed with Ph2CHNH2 to afford a mixture of 25, 26 and 27 in a ratio of 86 8 6. Removal of the benz-hydryl group from 25 by hydrogenation in the presence of Pd(OH)2 afforded 3 in 91 % yield. 

Heinen et al. [35] investigated the oxidation of D-fructose on Pt/C catalyst at 30 °C and pH 7.3. Oxidation of both the C, primary alcohol and the C5 secondary alcohol occurred. The reaction stopped at ca 80 % conversion giving mainly 2-keto-D-gluconic acid (45% selectivity) and D-t/n-eo-hexo-2,5-diulose or 5-ketofructose (27 % selectivity). In the presence of bismuth-promoted catalysts selectivity to the former was slightly increased. This was attributed to the complexation by bismuth of the y9-o-fructofuranose stmcture via the c/s-diol functions. 

In a study of the oxidation of D-mannose and o-galactose with an excess of sodium periodate, the amount of oxidant consumed (determined by potentiometric titration) was found to be less than quantitative for D-galactose after 90 min at pH 8—10. The influence of pH and the concentration of oxidant on the oxidation of D-fructose with periodate ion has also been studied. "... 

Kabir-ud-Din, A. M. A. Morshed, and Z. Khan, Influence of sodium dodecyl sulfate/TritonX-100 micelles on the oxidation of D-fructose by chromic acid in presence of HC104, Carbohydrate Research, vol. 337, no. 17, pp. 1573—1583, 2002. 

The oxidation of aldoses and sugar phosphates by Cr(VI) has been reviewed (23 refs.). The kinetic behaviour and the relative reactivities of several trioses, tetioses, pentoses and hexoses, amino sugars, and methylated sugars towards potassium permanganate in perchloric acid solution have been examined. Mechanisms have been proposed for the oxidation of arabinose and xylose by iodine in alkaline solution and by alkaline NBS under Ru(Vni)-catalysis. For the oxidation of monosaccharides by sodium iV-bromobenzenesulfonamide in alkaline media, reaction via 1,2-enediol intermediates has been postulated. 1 1 Stoichiometry has been observed in the oxidation of D-fructose with PCC. ... 

The enzyme activity of the FDH/Pt and the PP/FDH/Pt electrode was determined by the following method upon oxidation of D-fructose, the electron acceptor ferricyanide is reduced to ferrocyanide, which forms Prussian blue with Fe2(SO )3. The appearance of Prussian blue was measured spectrophotometirically at 660 nm. One unit of FDH catalyzes the oxidation of one micromole D-fructose (the formation of two micromole Prussian blue) per min. 

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