نتایج جستجو برای: deoxygenation
تعداد نتایج: 1314 فیلتر نتایج به سال:
Elevated atmospheric carbon dioxide (CO 2 ) is causing global ocean changes and drives in organism physiology, life-history traits, population dynamics of natural marine resources. However, our knowledge the mechanisms consequences acidification (OA) – combination with other climatic drivers (i.e., warming, deoxygenation) on organisms downstream effects fisheries limited. Here, we explored how ...
The synthesis of 6 beta-bromopenicillanic acid labeled with deuterium and tritium in the beta-methyl group is described. The S-sulfoxide of benzyl- or p-methoxybenzyl 6 alpha-bromopenicillanate is refluxed in benzene containing an excess of tert-BuOD, D2O or HTO. After deoxygenation and deprotection of the ester, the labeled 6 alpha-bromopenicillanic acid is epimerized (N,O-bis(trimethylsilyl)a...
As part of a programme aimed at exploiting lignin as a chemical feedstock for less oxygenated fine chemicals, several catalytic C-C bond forming reactions utilising guaiacol imidazole sulfonate are demonstrated. These include the cross-coupling of a Grignard, a non-toxic cyanide source, a benzoxazole, and nitromethane. A modified Meyers reaction is used to accomplish a second constructive deoxy...
Pyrrolizin-3-ones (e.g. 1) can be easily hydrogenated to their hexahydro (pyrrolizidin-3-one) derivatives in the presence of heterogeneous catalysts. Good diastereoselectivity (up to >97:3, depending on catalysts and solvent) can be achieved if the pyrrolizin-3-one is substituted at the 1- (or 7-) position(s), but the selectivity is reduced if both positions are substituted. Subsequent deoxygen...
Catalytic Pd(OAc)(2) and polymethylhydrosiloxane (PMHS), in conjunction with aqueous KF, and a catalytic amount of an aromatic chloride, effects the chemo-, regio-, and stereoselective deoxygenation of benzylic oxygenated substrates at room temperature in THF. Preliminary mechanistic experiments suggest the process to involve palladium-nanoparticle-catalyzed hydrosilylation followed by C-O redu...
A tandem organosolv pulping and Pd-catalysed transfer hydrogenolysis depolymerisation and deoxygenation has been developed. The tandem process generated 2-methoxy-4-(prop-1-enyl)phenol in 23% yield (92% theoretical monomer yield) starting from pine wood and 2,6-dimethoxy-4-(prop-1-enyl)phenol in 49% yield (92% theoretical monomer yield) starting from birch wood. Only endogenous hydrogen from wo...
Although the rheologic behavior of sickle erythrocytes (SS cells) is highly dependent on oxygen tension (pO2) and temperature, very little data exist regarding the effects of deoxygenation and reoxygenation on the rheology of "individual" SS cells at body temperature. We have devised and assessed a new experiment system, in which micropipette aspiration can be performed on individual cells in a...
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