Fructose platinum

Xylose and fructose. Xylose can be hydrogenated into xylitol (Scheme 13). This reaction was reported using hydrogenation catalysts such as Raney nickel as well as platinum group metal catalysts. ... 

Raney nickel, copper and platinum group metal catalysts have also been used as catalysts for transforming fructose into mannitol via catalytic hydrogenation (Scheme 14) 197-199,203,204 supported on carbon... 

Garcia et al., 1998 [107] Fructose Dietetic products Fructose 5-dehydrogenase/in a polypyrrole (PPY) film Platinum electrode/ +0.25 mV vs. Ag/AgCl Sodium ferricyanide... 

The interest in FDA arises from its possible application as a renewable-derived replacement for terephthalic acid in the manufacture of polyesters. A multitude of oxidation techniques has been applied to the conversion of HMF into FDA but, on account of the green aspect, platinum-catalyzed aerobic oxidation (see Fig. 8.35), which is fast and quantitative [191], is to be preferred over all other options. The deactivation of the platinum catalyst by oxygen, which is a major obstacle in large-scale applications, has been remedied by using a mixed catalyst, such as platinum-lead [192]. Integration of the latter reaction with fructose dehydration would seem attractive in view of the very limited stability of HMF, but has not yet resulted in an improved overall yield [193]. 

Bioelectrocatalytic properties were obtained for FDH at carbon and gold and platinum electrodes [111,113]. The catalytic oxidation current of FDH-modified carbon paste electrodes approached a maximum value at 4-0.5 V vs. Ag/AgCl. At this potential and under optimum conditions, i.e., pH 4.5, fi uctose can be measured between 0.2 and 20 mM in fi uit juices. Most importantly the fructose sensor was insensitive to ambient oxygen. 

Weygand and Bergmann investigated the oxidation of certain derivatives (known as Amadori products) of l-amino-l-deoxy-n-fructose. The oxidation of 1-deoxy-l-p-toluidino-n-fructose in 2 V ammonium hydroxide at 50° in the presence of a platinum-on-carbon catalyst led to the degradation of the compound to n-arabinonic acid, presumably according to the following sequence. 

Potential-controlled adsorption of fructose dehydrogenase onto a platinum electrode Fructose [50]... 

The electrocatal3rtic oxidation of sucrose has only been the subject of a few investigations. The chemical oxidation of sucrose was firstly mentioned in the works of Bresler (1) and Usch (2). Karabinos (3) analysed the oxidation products of fructose, glucose, glucono-y-lactone and sucrose in 0.5 M NaHCOa. The author concluded that the main reaction products were CO2 and H2O. Bockris et al. (4), investigated the electrochemical oxidation of different carbohydrates at platinum electrodes for their possible use in fuel cells. They noticed that the electroactivity was better in alkaline medium than in acidic medium, and that the reactivity of the molecule decreased with increasing molecular weights. 

J. Chen, T. Pill, and W. Beek, Metal complexes of biologieally important ligands. L. Palladiiun(II), platinum(II) and coppeifll) eomplexes of a-amino acid N-glycosides and of fructose amino aeids (Amadori eompounds), Z Naturforsch., B44 (1989) 459 64. 

Several research groups implemented carbohydrate analysis on-chip with direct detection of underivatized sugar molecules. Electrochemical detection is the most attractive approach, as it offers reasonable sensitivity and selectivity, and it is ideally suited for microchip format. Schwarz et al. [203] developed amperometric detection of sugars using microfabricated copper electrode. They separated fructose, sucrose, and galactose in 70 s on a glass chip with 50-p,m wide and 20-p,m deep microchannel and double tee injection geometry. The detection was based on Teflon-coated platinum wire plated with copper and inserted in the end of the separation channel etched in a conical shape. The detection limit down to 1 JtM was achieved. Hebert and coworkers [204] reported an... 

The catalytic oxidation of the carbohydrates in the presence of Cu(II) for the detection of sucrose, galactose, and fructose was exploited using a Teflon-coated platinum wire plated with copper as the working electrode. Therefore, the addition of copper ions in the run buffer increased the sensitivity to an order of magnitude compared to run buffer without copper. Detection limits were 1 pmol 1 ... 

The platinum oxide catalyst converts the hexitols to the corresponding aldoses and ketoses which are carried through the above series of reactions by the oxygen. Mannitol is oxidized by Pt02 to D-mannose, isolated as methyl a-mannoside in a yield of 20%. Fructose is formed simultaneously. With a platinum-activated carbon catalyst, L-sorbose has been converted to 2-keto-L-gulonic acid, 2,3-0-isopropylidene-L-sorbose to2,3-0-isopropyl-... 

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