Transfer hydrogenation

This study focused on the preparation of silver nanoparticles embedded on the supports such as bentonites, zeolites, activated carbon, zinc oxide, and aluminum oxide. Catalytic activity was evaluated via the transfer hydrogenation of 4-methoxybenzaldehyde. The results will be presented in this report.

5p vikwong 29-09-2024 4 2   Download

The results showed that the overall diffusioncontrolled rate constant is equal to 4.82×109 M-1 s -1 at 298.15K. The zwitterionic form is the main existing form that plays an essential role in the HO - initiated oxidation of Ile (99.98%). The most preponderant reactions are found at C6-H (36.19%) and C8-H (37.77%) positions. Finally, the influence of temperature on the overall rate is also evaluated.

8p dianmotminh02 03-05-2024 7 2   Download

The geometries and relative stabilities of 15 tautomeric forms and the corresponding isomers of the studied molecules have been identified and their relative stabilities are investigated. The potential energy profiles and intrinsic reaction coordinates (IRC) calculations along the proton transfer coordinates both in the ground and in the excited state are monitored as well. The impact of the donating (OMe) and withdrawing (NO2) groups on the single and double proton transfers are investigated both in the gas phase and solution.

9p dianmotminh02 03-05-2024 10 2   Download

TiO2-Graphene Oxide-Hemin (TiO2/GO/Hemin) ternary composite hybrid material was prepared by the sol-gel method and used as a heterogeneous catalyst for the photocatalytic degradation of organic contaminants. The catalytic activity of GO-TiO2-Hemin was evaluated by the degradation of Rhodamine B (RhB) under the UV-visible light irradiation and in the presence of hydrogen peroxide.

9p tamynhan4 06-09-2020 18 3   Download

Many biological C-H activation reactions exhibit nonclassical kinetic isotope effects (KIEs). These nonclassical KIEs are too large (kH/kD 7) and/or exhibit unusual temperature dependence such that the Arrhenius prefactor KIEs (AH/AD) fall outside of the semiclassical range near unity. The focus of this minireview is to discuss such KIEs within the context of the environmentally coupled hydrogen tunneling model.

9p system191 01-06-2013 37 4   Download

Recent years have witnessed high levels of activity in identifying enzyme systems that catalyse H-transfer by quantum tunneling. Rather than being restricted to a small number of specific enzymes as perceived initially, it has now become an accepted mechanism for H-transfer in a growing number of enzymes. Furthermore, H-tunneling is driven by the thermally induced dynamics of the enzyme. In some of those enzymes that break stable C–H bonds the reaction proceeds purely by quantum tunneling, without the need to partially ascend the barrier.

7p system191 01-06-2013 40 3   Download

Galloylated and nongalloylated catechin conjugates with cysteine deriva-tives have been synthesized and evaluated for their capacity to scavenge free radicals and to influence crucial functions (cell cycle, apoptosis) in HT29 colon carcinoma cells. We show that the nonphenolic part of the molecule modified the capacity of catechins to donate hydrogen atoms and to transfer electrons to free radicals.

12p inspiron33 26-03-2013 34 4   Download

His334 facilitates catalysis byCorynebacterium callunaestarch phosphory-lase through selective stabilization of the transition state of the reaction, partly derived from a hydrogen bond between its side chain and the C-6 hydroxy group of the glucosyl residue undergoing transfer to and from phosphate.

11p media19 04-03-2013 38 2   Download

At least half of all enzyme-catalysed reactions are thought to involve a hydrogen transfer. In the last 10 years, it has become apparent that many of these reactions will occur, in part, or in full, by quantum mechanical tunnelling. We are particularly interested in the role of promoting vibra-tions on H transfer, and the Old Yellow Enzyme family of flavoproteins has proven to be an excellent model system with which to examine such reactions.

12p vinaphone15 25-02-2013 25 4   Download

A look on energy, renewable energies, energy storage and synthetic fuels, hybrid architecture, fuel cells, hydrogen as a vector of energy of the future.The Earth resources are quite limited in quantity Many challenges to mankind in 21st century: development, health, water, food, demography, education, energy.In physics, energy (Ancient Greek: ἐνέργεια energeia "activity, operation"[1]) is a quantity that is often understood as the ability a physical system has to produce changes on another physical system.

156p dienquochuy 21-12-2012 82 21   Download

Catalytic oxidation of organic compounds is an extremely important field of chemistry, spanning the range from biological oxidations to large scale industrial production of commodity chemicals. However, many of these transformations can hardly be classified as organometallic reactions, since the catalysts (often simple metal salts) and the intermediates can be rather regarded as coordination complexes than organometallic compounds.

7p boyminsk 10-06-2010 103 18   Download