Effect of ceria loading on the carbon formation during low temperature methane steam reforming over a Ni/CeO2/ZrO2 catalyst

The characterization and catalytic activity of a Ni/CeO₂/ZrO₂ catalyst for methane steam reforming at 600°C were investigated. The addition of ceria increased the surface area and basicity of the catalysts. The redox reaction capability of the ceria increased the hydrogen yield and carbon monoxide selectivity, and inhibited carbon formation.     

Action of manganese dioxide on carbohydrates—I Some disaccharides

Manganese dioxide degrades 1 → 3, 1 → 4 and 1 → 6 linked hexose disaccharides to, inter alia, 1 → 2, 1 → 3 and 1 → 5 linked hexosyl-pentoses, respectively. The yields (18–31 per cent) compare favourably with those recorded for other degradations. The methods which have been worked out for the isolation of these products are experimentally straightforward, and should be generally applicable to mixtures obtained by oxidation of 3-, 4- and 6-substituted hexoses with manganese dioxide.     

"Molecular chameleons". Design and synthesis of C-4-substituted imidazole fleximers

The synthesis of two flexible nucleosides is presented. The "fleximers" feature the purine ring system split into its imidazole and pyrimidine components. This modification serves to introduce flexibility to the nucleoside while still retaining the elements essential for molecular recognition. As a result, these structurally innovative nucleosides can more readily adapt to capricious binding sites and, as such, should find use for investigating enzyme-coenzyme as well as nucleic acid-protein interactions.     

Conformations of monoacyl and 1,3-diacylbenzimidazoline-2-thiones and dihydrobenzimidazoles

The endo confrontation of monoacyl and 1,3-diacylbenzimidazoline-2-thiones is predominant at ambient temperatures. Nmr temperature-dependent studies suggest that this is also true over a wide range of temperatures. In agreement with previous results (6) the exo-endo conformation in 1,3-diacyl-1,2-dihydrobenzimidazoles is generally the predominant one.     

Reaction of acetylenic ketones with hydrazine derivatives. Synthesis of hydroxypyrazoles

Aroylphenylacetylenes Ia-c react with (-butyl hydrazinecarboxylate (IIa) and 2-furylhydrazide (IIb) to give the corresponding hydroxydihydropyrazole derivatives IVa-f. This cyclic structure is supported by chemical transformations. Thus, when compounds IVa-c are heated with acetic anhydride, they yield the corresponding 5-aryl-1-(t-butoxycarbonyl)-3-phenylpyrazoles Va-c which, upon hydrolysis with methanolic potassium hydroxide, produce the corresponding 5(3)aryl-3(5)phenylpyrazoles VI. Spectroscopic data also confirm the suggested cyclic structure IV.     

Gas‐phase fragmentation study of biotin reagents using electrospray ionization tandem mass spectrometry on a quadrupole orthogonal time‐of‐flight hybrid instrument

In this study, we evaluated, by electrospray ionization mass spectrometry (ESI‐MS) and collision‐induced dissociation tandem mass spectrometry (CID‐MS/MS) using a quadrupole orthogonal time‐of‐flight (QqToF)‐MS/MS hybrid instrument, the gas‐phase fragmentations of some commercially available biotinyl reagents. The biotin reagents used were: psoralen‐BPE 1, p‐diazobenzoyl biocytin (DBB) 2, photoreactive biotin 3, biotinyl‐hexaethyleneglycol dimer 4, and the sulfo‐SBED 5. The results showed that, during ESI‐MS and CID‐MS/MS analyses, the biotin reagents followed a similar gas‐phase fragmentation pattern and the cleavages usually occurred at either end of the spacer arm of the biotin reagents. In general we have observed that the CID‐MS/MS fragmentation routes of the five precursor protonated molecules obtained from the biotin linkers 1–5 afforded a series of product ions formed essentially by similar routes. The genesis and the structural identities of all the product ions obtained from the biotin linkers 1–5 have been assigned. All the exact mass assignments of the protonated molecules and the product ions were verified by conducting separate CID‐MS/MS analysis of the deuterium‐labelled precursor ions. Copyright © 2009 John Wiley & Sons, Ltd.