Systematic theoretical studies for the mechanisms of the epoxidation and complete oxidation of ethylene and propylene over silver surface as well as the reactivity and the stability of oxygen species on Cu, Ag, and Au surfaces have been presented. The Ž . Ž . dipped adcluster model DAM combined with the ab initio Hartree]Fock HF , secondŽ . Ž order Møller-Plesset MP2 , and SACrSAC-CI symmetry-a...

Being widely used, medicinal products based on vegetable oils require strict regulation and evaluation of quality attributes, determination shelf-life periods, monitoring storage conditions. The most common testing method for unsaturated compounds in is the iodine value determination, which has a range limitations. An alternative determining degree unsaturation epoxidation. aim study was to eva...

Asymmetric epoxidation is one of the most important transformations in organic synthesis. Although tremendous progress was achieved in this field in the 1980s and 1990s, it is still desirable from both economical and ecological views to develop environmentally friendly catalytic epoxidation with a broad substrate scope. Hydrogen peroxide is a safe and cheap oxidant, which is easy to handle and ...

Presented are density functional calculations on various Mn(salen) systems that are active catalysts in the epoxidation of olefins. Correlation of various structural properties such as Mn=O bond strengths, atomic charges, and C-O distances of evolving bonds in transition state geometries with modified Hammett constants reveal a mechanistic picture of the epoxidation reaction, supporting previou...

[structure: see text] Collagen is the most abundant protein in animals. Interstrand N-H...O=C hydrogen bonds between backbone amide groups form a ladder in the middle of the collagen triple helix. Isosteric replacement of the hydrogen-bond-donating amide with an ester or (E)-alkene markedly decreases the conformational stability of the triple helix. Thus, this recurring hydrogen bond is critica...

The regioselective synthesis of allylic hydroperoxide sulfonates by singlet oxygenation at the air-water interface has been found to depend on the concentration of the alkene sulfonate and added calcium salt. The regioselectivity is proposed to originate from an orthogonal alkene relative to the water surface for preferential methyl hydrogen abstraction by airborne singlet oxygen in an ene reac...

The surface of magnetite nanoparticles as nano-sized solid support was modified with a molybdenum-Schiff base complex to prepare an easily separable heterogeneous catalyst for the epoxidation of olefins. Characterization techniques such as Fourier transform infrared and inductively coupled plasma optical emission spectroscopies, X-ray diffraction, vibrating sample magnetometry, scanning, an...

A solvent-free semihydrogenation of 2-methyl-3-butyn-2-ol (MBY) to 2-methyl-3-buten-2-ol was performed in a capillary reactor (10 m long, 0.53 mm i.d.) coated with a titania supported Pd-Bi catalyst. Several coatings with different Pd/Bi ratio have been prepared. The catalysts have been characterized with SEM, TEM, EDX, XRD analysis and N2 adsorption-desorption measurements. The maximum alkene ...

A broad perspective of various factors influencing alkene selenenylation has been developed by concurrent detailed analysis of key experimental and theoretical data, such as asymmetric induction, stereochemistry, relative reactivities, and comparison with that of alkene sulfenylation. Alkyl group branching α to the double bond was shown to have the greatest effect on alkene reactivity and the s...

The catalytic properties of Al2O3-supported vanadia with a wide range of VOx surface density (1.4-34.2 V/nm) and structure were examined for the oxidative dehydrogenation of ethane and propane. UV-visible and Raman spectra showed that vanadia is dispersed predominately as isolated monovanadate species below ~2.3 V/nm. As surface densities increase, two-dimensional polyvanadates appear (2.3-7.0 ...