Oxidation of Sugar Derivatives

Gold nanoparticles supported on nanocrystalline cerium oxide, are extremely effective in the oxidation of aldehydes to acids and also in the oxidation of alcohols (see Vivier and Duprez and references therein).  

A key intermediate in the synthesis of a number of pharmaceuticals, antifungals, and polymer precursors is 5-hydroxymethyl-2-fur-fural (HMF), which is produced by the dehydration of fructose or glucose. Of these applications, the synthesis of polymer precursors is of interest. For example, 2,5-furandicarboxylic acid (FDCA) can replace terephthalic acid commonly used in the manufacture of poly (ethylene terephthalate) (PET). 

HMF has been selectively converted into FDCA (99 mol% yield) in water, under mild conditions (65-130°C, 10 bar air) using gold nanoparticles on nanoparticulated ceria. ° As an alternative to FDCA, 2,5-dimethylfuroate (FDMC) has also been synthesized using the same catalyst in the absence of a base in methanol. The oxidation of HMF into FDCA or FDMC comprises two steps aldehyde oxidation and alcohol oxidation. Kinetic studies show that the rate-limiting step of the reaction is alcohol oxidation to aldehyde. Once the aldehyde is formed, the corresponding hemiacetal is obtained, which is rapidly oxidized into the acid or the ester (Fig. 13.5). 

The selective oxidation of arabinose to arabinonic acid by molecular oxygen has been carried out at 60°C in water on monometallic and bimetallic Pd-Au catalysts supported on nanosized ceria. Arabinose is extracted from a hemicellulose called arabi-nogalactan found in larch species, with galactose and D-glucuronic 

The redox ability and the acid-base properties of CeOg, either alone or in the presence of transition metals, are important parameters that activate complex organic molecules and selectively orient their transformation. The acid-base or redox properties of ceria can also be modified by involving other oxides (ZrOg, LagOg, MnO, ZnO, M0O4, VOx,. ..) thus increasing the scope of the reactions. Ceria has been used as a support of noble metal catalysts (Pd, Pt, Rh, Au) in the 

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Various substituted N-hiomo- and A/-chloroureas have also been prepared (97). These compounds are useful for synthesis of oxazoUdinones, and also hydrazine, hydrazo, and azo compounds. A/-Bromourea [51918-81 -1] is useful for selective oxidation of sugar derivatives (98). 

Fig. 2.—Oxidation of sugar derivatives by lead tetraacetate in dry acetic acid 0.00025 mole substance in 100 cc. ratio of Pb(OAc)4 to substance, 15.2/1 water less than 0.05 %.

J. Kiss, Oxidation of sugar derivatives with bromocarbamide, Chem. Ind. (London), (1964) 73. 

Analytically pure lactones were obtained by oxidation of sugar derivatives, having the anomeric hydroxyl group free, with tetra-ra-propylammonium tetraoxo-ruthenate(VII) and tV-methylmorpholine tV-oxide as cooxidant.138... 

Deoxy-sugars. Part XXVII. The Catalytic Oxidation of Some Derivatives of 2-Deoxy-D-hexoses, W. G. Overend, F. Shafizadeh, M. Stacey, and G. Vaughan,/. Chem. Soc., (1954) 3633-3634. 

Oxidation of Isopropylidene Derivatives of Ketose Sugars. Whenever isopropylidene derivatives can be obtained in which all groups except the primary alcoholic grouping at Cl are blocked this method is undoubtedly the best. It may be illustrated by reference to the preparation of 2-keto-D-gluconic acid from D-fructose.14... 

T. K. M. Shing, W. F. Wong, H. M. Cheng, W. S. Kwok, and K. H. So, Intramolecular nitrile oxide-alkene cycloaddition of sugar derivatives with unmasked hydroxyl group(s), Org. Lett., 9 (2007) 753-756. 

The effects of such oxidants as a mixture of potassium iodate and dichromate in concentrated sulfuric and phosphoric acids (van Slyke reagent), hot solutions of chromic acid, and acidic solutions of ceric sulfate, permanganate, periodate, and hyperoxidized transition metals on a number of sugar derivatives has been described (Ref. 1, pp. 1151-1153). 

Panzer obtained a gel-like carbohydrate substance from defatted bacilli (human strain) by successive extraction with water, hydrochloric acid, sodium carbonate, sodium nitrate, hot water and potassium hydroxide. The resulting liquors each yielded a gum-like substance which was sulfur-, nitrogen- and phosphorus-free. Oxidation of this derivative with nitric acid gave oxalic acid but no mucic acid. Panzer concluded that the substance was probably a pectin but not a galactan. It is now known that drastic oxidation of this nature would give oxalic acid from any sugar derivative. It is possible that by using controlled oxidation, mucic acid could be obtained from this carbohydrate. 

NA hen Harries (2) at the beginning of the present century carried out his fundamental experiments with a view to ozonizing organic compounds, he also studied the effect of ozone on certain sugar alcohols. His initial studies showed that the primary alcoholic hydroxyls of sugar derivatives can be oxidized to form aldehyde groups by utilizing ozone. 

CAS 56-82-6. IKK IUd 1,0010. Isomeric with dihydroxyacetone. It is produced by the oxidation of sugars in the body. As the simplest aldose, the conformation of d- and L-glyceraldehydes has been designated the reference standard for d- and L-carbohy-drates and derivatives. 

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