Search results for "Reaction"

State-to-State Quantum Dynamics Calculations of the C plus OH Reaction on the Second Excited Potential Energy Surface

2011

Accurate three-dimensional quantum-mechanical scattering calculations using a time-indepedent hyperspherical method have been performed for the C((3)P) + OH(X(2)Π) → CO(a(3)Π) + H((2)S) reaction on the second excited potential energy surface of 1(4)A″ symmetry. State-to-state reaction probabilities at a total angular momentum J = 0 have been computed in a wide range of collision energies. Many pronounced resonances have been found, espcially at low energy. The product vibrational distributions are noninverted. The present results therefore suggest that the title reaction proceeds via a long-lived intermediate complex. An approximate quantum-mechanical rate constant has also been calculated,…

Anomalous solvent extraction behavior of astatine

1997

We studied the solvent extraction behavior of astatine and found the anomalous behavior of this element similar to radioiodine. Astatine was extracted into CS2 from acidic solution over a wide range of carrier iodine concentration. The distribution ratios of astatine were determined by measuring the γ-ray from 210 At with a Nal(TI) detector. A drastic change was observed around at 10−4 mol/l as in the case of 131 I. This tendency is well explained by the kinematics of the chemical reactions concemed.

Species- and Subtype-Specific Recognition by Antibody WF6 of a Sequence Segment Forming an α-Bungarotoxin Binding Site on the Nicotinic Acetylcholine…

1992

The monoclonal antibody WF6 competes with acetylcholine and alpha-bungarotoxin (alpha-BGT) for binding to the Torpedo nicotinic acetylcholine receptor (nAChR) alpha 1 subunit. Using synthetic peptides corresponding to the complete Torpedo nAChR alpha 1 subunit, we previously mapped a continuous epitope recognized by WF6, and the prototope for alpha-BGT, to the sequence segment alpha 1(181-200). Single amino acid substitution analogs have been used as an initial approach to determine the critical amino acids for WF6 and alpha-BGT binding. In the present study, we continue our analysis of the structural features of the WF6 epitope by comparing its cross-reactivity with synthetic peptides corr…

Second-order tensorial calibration for kinetic spectrophotometric determination

1996

Abstract Kinetic-diode array spectrophotometric detection, as well as other multichannel techniques when used in non-equilibrium conditions, constitute second-order instrumentation. The second-order response provided will be bilinear, under certain conditions even trilinear, thus allowing the use of the generalized rank annihilation method (GRAM) and the trilinear decomposition method (TLD). Both numerically simulated and experimental data were used to evaluate the performance of these calibration techniques. The conditions in which the ‘second-order advantage’ (the possibility of quantifying the analytes in the presence of unknown reactions or interferences) is preserved were investigated.…

α1-Adrenoceptors in the rat cerebral cortex: New insights into the characterization of α1L- and α1D-adrenoceptors

2010

36 p., figuras y tablas, bibliografía

The Mechanism of Photoinhibition of Spinach Thylakoids

1990

There is conflicting evidence as to wether D1-protein is the primary target of photoinhibition [1] or P680, the reaction centre of photo-system II [2]. The present paper desribes photoinhibition within a two step process consisting of an oxygen radical induced inactivation at the QB-site followed by damage to reaction centre II through the degradation of the D1-protein.

Studien zum Vorgang der Wasserstoffübertragung, 39. Langlebige Hydrierkatalysatoren durch kovalente Verknüpfung von Phosphin-Rhodium-Komplexen an Aer…

1976

Homogene Phosphin-Rhodium-Katalysatoren werden durch kovalente Bindung an ‘Aminoaerosil’ heterogenisiert. Die Abhangigkeit der Hydriergeschwindigkeit von der Entfernung der aktiven Zentren zur Oberflache, von der Temperatur, vom Losungsmittel und von der Struktur der eingesetzten Olefine wird untersucht. Studies on the Occurrence of Hydrogen Transfer, 39. — Long-Lived Hydrogenation Catalyst by Covalent Fixation of Phosphine-Rhodium-Complexes on the Surface of Aerosil 200 The covalent binding of hitherto homogeneous phosphine-rhodium catalysts to “Amino-aerosil” is described. The dependence of the rate of catalysed hydrogenation upon the distance between the reaction centre and the silica su…

2019

The preparation of unprecedented 6,12-disubstituted methanodibenzo[b,f][1,5]dioxocins from pyrrolidine catalyzed self-condensation of 2′-hydroxyacetophenones is herein described. This method provides easy access to this highly bridged complex core, resulting in construction of two C–O and two C–C bonds, a methylene bridge and two quaternary centers in a single step. The intricate methanodibenzo[b,f][1,5]dioxocin compounds were obtained in up to moderate yields after optimization of the reaction conditions concerning solvent, reaction times and the use of additives. Several halide substituted methanodibenzo[b,f][1,5]dioxocins could be prepared from correspondent 2′-hydroxyacetophenones.

Diastereoselective Synthesis of Spiro[pyrazolone-4,3′-tetrahydrothiophenes] via a Sulfa-Michael/Aldol Domino Reaction

2016

Synthesis : journal of synthetic organic chemistry 48(23), 4091-4098(2016). doi:10.1055/s-0035-1562473

Visible-light-accelerated amination of quinoxalin-2-ones and benzo[1,4]oxazin-2-ones with dialkyl azodicarboxylates under metal and photocatalyst-fre…

2021

A direct sp3 C-H amination of cyclic amines (dihydroquinoxalinones and dihydrobenzoxazinones) with dialkyl azo dicarboxylates accelerated by visible-light irradiation under metal and photocatalyst-free conditions is described. This protocol features very mild reaction conditions for the synthesis of aminal quinoxaline and benzoxazine derivatives with good to high yields (up to 99%). These aminal derivatives respresent versatile building blocks for the divergent synthesis of quinoxalin-2-one derivatives.