نتایج جستجو برای: glycoluril based catalysts
تعداد نتایج: 2960450 فیلتر نتایج به سال:
The reaction of glycerol with urea to form glycerol carbonate is mostly reported in the patent literature and to date there have been very few fundamental studies of the reaction mechanism. Furthermore, most previous studies have involved homogeneous catalysts whereas the identification of heterogeneous catalysts for this reaction would be highly beneficial. This is a very attractive reaction t...
preparation of 2-chlorobenzonitrile, and benzonitrile are reported here from the corresponding 2-chlorobenzaldehyde and benzaldehyde by the reaction of ammonium hydroxide/vpo titania, vpo bulk (ammonium metavanadate) cucr catalyst/air system in methanol. all these catalysts showed better conversions with reasonable selectivity to aromatic. the results prove that bet surface area results show vp...
Chiral rhodium complexes covalently anchored on carbon nanotubes for enantioselective hydrogenation.
Chiral rhodium hybrid nanocatalysts have been prepared by covalent anchorage of pyrrolidine-based diphosphine ligands onto functionalized CNTs. This work constitutes the first attempt at covalent anchoring of homogeneous chiral catalysts on CNTs. The catalysts, prepared with two different chiral phosphines, were characterized by ICP, XPS, N2 adsorption and TEM, and have been tested in the asymm...
Having a strong electron-withdrawing ability, poly(diallyldimethylammonium chloride) (PDDA) was used to create net positive charge for carbon atoms in the nanotube carbon plane via intermolecular charge transfer. The resultant PDDA functionalized/adsorbed carbon nanotubes (CNTs), either in an aligned or nonaligned form, were demonstrated to act as metal-free catalysts for oxygen reduction react...
This review focuses on the chemical methods used to prepare supported bimetallic heterogeneous catalysts, i.e., bimetallic nanoparticles deposited on a support. The review is limited to the preparation of gold-based bimetallic catalysts and moreover to bimetallic nanoparticles supported on powder inorganic supports, i.e., on the surface or in the porosity, and not on model supports such as sing...
We report the development of ruthenium-based metathesis catalysts with chelating N-heterocyclic carbene (NHC) ligands that catalyze highly Z-selective olefin metathesis. A very simple and convenient procedure for the synthesis of such catalysts has been developed. Intramolecular C-H bond activation of the NHC ligand, promoted by anion ligand substitution, forms the appropriate chelate for stere...
The activities of a series of MoS(2)-based hydrogen evolution catalysts were studied by biphasic reactions monitored by UV/Vis spectroscopy. Carbon supported MoS(2) catalysts performed best due to an abundance of catalytic edge sites and strong electronic coupling of catalyst to support.
Here, we demonstrate a versatile screening platform for NHC ligand based catalysts by coating fused-silica micro capillaries with a bonded 1,3-bismesityl-2-imidazolidinylidene ligand. Such micro capillaries can be efficiently converted into (pre)-catalysts from various organometallic precursors by solid-phase chemistry techniques and can be quantitatively screened using on-column reaction chrom...
High pressure X-ray photoelectron spectroscopy (XPS) is used to characterize heterogeneous catalytic processes. The success of the new technique based on the possibility to correlate the catalytic activity and the electronic structure of an active surface. The dynamic character of a catalyst surface can be demonstrated impressively by this technique. In this contribution the basics of high pres...
Multimodal tumor imaging with targeted nanoparticles potentially offers both enhanced specificity and sensitivity, leading to more precise cancer diagnosis and monitoring. We describe the synthesis and characterization of phenol-substituted, lipophilic orange and far-red fluorescent dyes and a simple radioiodination procedure to generate a dual (optical and nuclear) imaging probe. MALDI-ToF ana...
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