Proton transfer reactions

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.

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Ebook "Hydrogen transfer reactions: Reductions and beyond" provides readers with contents including: metal-catalysed transfer hydrogenation of ketones; imino transfer hydrogenation reductions; organocatalytic transfer hydrogenation and hydrosilylation reactions; proton-coupled electron transfer in organic synthesis - fundamentals, applications, and opportunities; hydrogen-atom transfer reactions;...

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Ebook "Advances in photochemistry (Volume 27)" offers critical evaluations written by internationally recognized experts. These pioneering scientists offer unique and varied points of view of the existing data. Their articles are challenging as well as provocative and are intended to stimulate discussion, promote further research, and encourage new developments in the field.

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The acid dissociation constant is an important parameter that affects the physicochemical properties of molecules in solution. A set of 20 phenolic compounds were used to establish a model to predict pKa values of phenolic compounds.

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The electrochemical oxidation of 2,6-diaminopurine (2,6-DAP) was studied in pH 7.4 phosphate buffer solution on multiwall carbon nanotube modified glassy carbon electrode (MWCNT/GCE) over a temperature range of 20 to 50 ◦ C using cyclic voltammetry. 2,6-DAP oxidation on MWCNT/GCE showed a well-defined and irreversible oxidation peak at about 0.72 V vs. Ag/AgCl at pH 7.4. The oxidation potential of 2,6-DAP linearly varied with pH over the range of 3.0 to 10.0 with a slope of –0.0547 V/pH, implying that 2 protons were accompanied by 2 electrons transferred in the electrochemical reaction.

10p langthannam 29-12-2021 10 0   Download

Starting from a chiral secondary alcohol, novel enantiopure 1,4-aminoalkylphenols (AAPs) were prepared by exploiting conventional organic transformations such as the Mitsunobu reaction, Eschweiler–Clarke N -methylation, and demethylation of anisoles. The catalytic activity of the 1,4-AAPs was investigated in enantioselective Et2Zn addition to benzaldehyde. They were found to accelerate the Et2Zn addition to benzaldehyde. High yields and enantioselectivities (e.g., 95% yield and 82% ee) were achieved.

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Exhaled breath volatile organic compound (VOC) analysis for airway disease monitoring is promising. However, contrary to nitric oxide the method for exhaled breath collection has not yet been standardized and the effects of expiratory flow and breath-hold have not been sufficiently studied. These manoeuvres may also reveal the origin of exhaled compounds.

7p vimontana2711 05-04-2021 12 1   Download

The roles of His181, His184 and Tyr186 in PETN reductase have been examined by mutagenesis, spectroscopic and stopped-flow kinetics, and by determination of crystallographic structures for the Y186F PETN reductase and reduced wild-type enzyme—progesterone complex. Residues His181 and His184 are important in the binding of coenzyme, steroids, nitro-aromatic ligands and the substrate 2-cyclohexen-1-one.

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The solubility of a partially soluble salt is decreased when a common ion is added. Consider the equilibrium established when acetic acid, HC2H3O2, is added to water. At equilibrium H+ and C2H3O2- are constantly moving into and out of solution, but the concentrations of ions is constant and equal. If a common ion is added, e.g. C2H3O2- from NaC2H3O2 (which is a strong electrolyte) then [C2H3O2-] increases and the system is no longer at equilibrium. So, [H+] must decrease.

45p tranvtue 02-11-2012 56 3   Download

Acid: vị chua, làm thuốc nhuộm đổi màu Bases: vị đắng, cảm giác nhớt. Arrhenius: acids làm tăng [H+], bases làm tăng [OH-] trong dung dịch. Arrhenius: acid + base  salt + water. Problem: định nghĩa này chỉ áp dụng được trong dung dịch nước The H+ Ion in Water The H+(aq) ion is simply a proton with no electrons. (H has one proton, one electron, and no neutrons.) In water, the H+(aq) form clusters. The simplest cluster is H3O+(aq). Larger clusters are H5O2+ and H9O4+. Generally we use H+(aq) and H3O+(aq) interchangeably....

45p tranvtue 02-11-2012 56 2   Download