7 research outputs found
The adsorption and decomposition of carbon monoxide on Ni(100) and the oxidation of the surface carbide by oxygen
The interaction of carbon monoxide with Ni(100) has been studied by ellipsometry and Auger electron spectroscopy. Bombardment by electrons of a relatively high energy (2500 eV) leads to the disproportionation of the adsorbed CO (2 COad â Cad + CO2g ). The rate of oxidation of this surface carbide is , where hc is the carbon 272 eV Auger peak height, n=0.5 and the apparent activation energy Eact =13.3 kcal/mole. This relation is valid at 200â400°C and at oxygen pressures of 5 Ă 10â9â8 Ă 10â7 Torr
Heavily fluorinated carbohydrates as enzyme substrates: oxidation of tetrafluorinated galactose by galactose oxidase
Galactose oxidase (GOase) was shown to oxidise several C2/C3 fluorinated galactose analogues. Interestingly, the enzyme was able to distinguish between the 2,3-tetrafluorinated galactose and its epimeric glucose analogue, and this represents the first reported biotransformation of a heavily fluorinated suga
Enantioselective synthesis of tetrafluorinated glucose and galactose
Polyfluorinated carbohydrates have emerged as interesting probes to investigate âpolar hydrophobicityâ effect(s) in protein?carbohydrate interactions. A convenient enantioselective synthesis of tetrafluorinated analogues of two of the most important monosaccharides, d-glucose and d-galactose, is reported, as well as our first results regarding the glycosylation of these sugar analogues
Investigations into the utility of high-âsurface area silica pellets as potential solid-âphase synthesis supports
Grace-Davidson silica pellets (SMR-057-015) are found to be optimal for surface grafting of (RO)3Si(CH2)3FG reagents. While loadings of up to 2.1 mmol gâ1 can be attained (ca. 0.05 mmol per pellet) access of further reagents to the graft sites is problematic above loadings of 0.8 mmol gâ1. 13C CPMAS NMR studies may be carried out on individual pellets (using natural abundance substrates) and the resulting spectra are diagnostic in identifying successful subsequent coupling reactions.
Sequential synthesis can be attained on mesoporous silica pellets and monitored by solid-state 13C NMR spectroscopy
Heavily fluorinated carbohydrates as enzyme substrates: Oxidation of tetrafluorinated galactose by galactose oxidase
Galactose oxidase (GOase) was shown to oxidise several C2/C3 fluorinated galactose analogues. Interestingly, the enzyme was able to distinguish between the 2,3-tetrafluorinated galactose and its epimeric glucose analogue, and this represents the first reported biotransformation of a heavily fluorinated sugar. © 2011 The Royal Society of Chemistry
Enantioselective synthesis of tetrafluorinated ribose and fructose
A perfluoroalkylidene lithium mediated cyclisation approach for the enantioselective synthesis of a tetrafluorinated aldose (ribose) and of a tetrafluorinated ketose (fructose), both in the furanose and in the pyranose form, is described