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111.
Exceedingly Facile PhX Activation (X=Cl,Br, I) with Ruthenium(II): Arresting Kinetics,Autocatalysis, and Mechanisms
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Dr. Fedor M. Miloserdov Dr. David McKay Dr. Bianca K. Muñoz Dr. Hamidreza Samouei Prof. Stuart A. Macgregor Prof. Vladimir V. Grushin 《Angewandte Chemie (International ed. in English)》2015,54(29):8466-8470
[(Ph3P)3Ru(L)(H)2] (where L=H2 ( 1 ) in the presence of styrene, Ph3P ( 3 ), and N2 ( 4 )) cleave the Ph? X bond (X=Cl, Br, I) at RT to give [(Ph3P)3RuH(X)] ( 2 ) and PhH. A combined experimental and DFT study points to [(Ph3P)3Ru(H)2] as the reactive species generated upon spontaneous loss of L from 3 and 4 . The reaction of 3 with excess PhI displays striking kinetics which initially appears zeroth order in Ru. However mechanistic studies reveal that this is due to autocatalysis comprising two factors: 1) complex 2 , originating from the initial PhI activation with 3 , is roughly as reactive toward PhI as 3 itself; and 2) the Ph? I bond cleavage with the just‐produced 2 gives rise to [(Ph3P)2RuI2], which quickly comproportionates with the still‐present 3 to recover 2 . Both the initial and onward activation reactions involve PPh3 dissociation, PhI coordination to Ru through I, rearrangement to a η2‐PhI intermediate, and Ph? I oxidative addition. 相似文献
112.
Robabeh Baharfar Zahra Rahmani Mojtaba Mohseni Razieh Azimi 《Natural product research》2015,29(22):2145-2148
This study was designed to examine the total phenolic and flavonoid contents, radical scavenging and antibacterial activity of the ethanolic extracts from leaves, berries and stems of Hedera pastuchovii Woron. ex Grossh. The berry extract, which contained the highest phenolic and flavonoid compounds, showed an appreciable DPPH√ scavenging ability in comparison with leaf and stem extracts. The various extracts exhibited moderate to good activity against both Gram-negative and Gram-positive bacteria, and the effectiveness of leaf extract was higher for all tested bacteria. 相似文献
113.
A new furanodihydrobenzoxanthone, artomandin (1), together with three other flavonoid derivatives, artoindonesianin C, artonol B, and artochamin A, as well as β-sitosterol were isolated from the stem bark of Artocarpus kemando. The structures of these compounds were determined on the basis of spectral evidence. All of these compounds displayed inhibition effects to a very susceptible degree in cancer cell line tests. Compound 1 also exhibited significant antioxidant capacity in the free radical 1,1-diphenyl-2-picrylhydrazyl tests. 相似文献
114.
Hamidreza Shahverdi Mehran Sohrabi Mahmoud Jamiolahmady 《Transport in Porous Media》2011,90(3):911-926
We present a new history matching method based on a Genetic Algorithm to estimate three-phase k
r (relative permeability) from unsteady-state coreflood experiments. In this method, relative permeabilities (k
r) are represented by quadratic B-Spline functions. Adjustable coefficients in k
r functions are changed in an iterative process to minimize an objective function. The objective function is defined as the
difference between the measures and simulated values of the pressure drop across the core and fluids recovery during the experiment.
One of the main features of this approach is that water and gas relative permeabilities (k
rw and k
rg) are assumed to be functions of two independent saturations as opposed to most of the existing empirical k
r models in which k
rw and k
rg are assumed to be only dependent of their own saturations. Another important aspect of this algorithm is that it considers
inequality constrains to ensure that physically acceptable k
r curves are maintained throughout the iterative optimization process. A three-phase coreflood simulator has been developed
based on this methodology that generates best k
r values by matching experimental data. The integrity of the developed software was first successfully verified by using two
sets of experimental three-phase k
r data published in the literature. Then, the results of some three-phase coreflood experiments carried out in our laboratory
were used to obtain three-phase k
r curves by this approach. 相似文献
115.
Microchimica Acta - We report on a rapid and effective method for the determination of methylcyclopentadienyl-manganese tricarbonyl (MMT) in water and gasoline samples. It is based on single drop... 相似文献
116.
Tabei ES Samouei H Rashidi M 《Dalton transactions (Cambridge, England : 2003)》2011,40(43):11385-11388
An unprecedented example of a platinum(II) complex with simultaneous formation of intermolecular NH···I-Pt and CH···I-Pt H-bondings (with neighboring platinum center) and an intramolecular CH···Pt hydrogen bonding in solid state is described. There are indications showing that the complex in solution probably forms a different kind of H-bonding type interaction. 相似文献
117.
Parhoodeh P Rahmani M Hashim NM Sukari MA Lian GE 《Molecules (Basel, Switzerland)》2011,16(3):2268-2273
During our phytochemical investigation of Haplophyllum villosum (Rutaceae), a perennial herb from Iran, a new 4,8-diaryl-3,7-dioxobicyclo-(3,3,0)-octane type lignan, eudesmin A (1), together with four known compounds--eudesmin (2), haplamine (3), umbelliferone (4) and scopoletin (5)--were isolated from aerial parts of the plant. The structures of the compounds were elucidated using NMR spectral analysis (1H-NMR, 13C-NMR, HSQC, COSY and HMBC) as well as UV, IR and MS spectra and comparison with previously reported data. 相似文献
118.
A. K. Singh S. Yadav J. Srivastava S. Rahmani R. K. Singh S. Srivastava 《Journal of the Iranian Chemical Society》2011,8(3):622-635
The kinetic and mechanistic studies of homogeneously Rh(III)-catalysed oxidation of D-xylose and L-sorbose by Nbromoacetamide (NBA) in perchloric acid medium were carried out at 40 °C. The reactions were first-order with respect to each of [NBA], [Rh(III)] and [H+] and zero-order in [sugar]. Variation of [Cl?] showed positive effect while variation of [Hg(OAc)2] showed negative effect on the rate of the reactions. Addition of acetamide (NHA) had a negative effect on the rate of the reaction. The rate of the reaction was unaffected by the change in ionic strength (??) of the medium. Various activation parameters were calculated with the help of pseudo-first-order rate constant, k1, obtained at four different temperatures. The mechanisms involving RhCl4(H2O)2 ?, as reactive species of rhodium(III), and H2OBr+, as reactive species of NBA, are proposed which find support from the spectrophotometric evidence and activation parameters, especially the entropy of activation. 相似文献
119.
We compute fractal dimension and permutation entropy for healthy and people who have experienced heart failure. Our result shows that permutation entropy is a suitable approach as well as detrend fluctuation analysis (DFA). The result of DFA shows that the fractal dimensions for healthy and heart failure are different as well as the permutation entropy result. The fluctuation value for permutation entropy for an individual who has experienced heart failure is bigger than for a healthy person. There is some specific change in the interbeat signal of a person who has experienced heart failure, but there is not previous trend for a healthy person. 相似文献
120.
Mohammad Rahmani 《代数通讯》2013,41(11):4361-4372
The purpose of this paper is to calculate all the character tables of Hecke algebras associated with finite Chevalley groups of exceptional type and their maximal parabolic subgroups when they are commutative. In the case when the groups are of classical type, the character values of Hecke algebras are expressed by using the q-Krawtchouk polynomials and the q-Hahn polynomials (See [10] and [15]). On the other hand, the character tables of commutative Hecke algebras associated with exceptional Weyl groups and their maximal parabolic subgroups are given in [12]. In §1, we discuss the structure of Hecke algebras and in §2, we calculate all the character tables of these commutative Hecke algebras associated with finite Chevalley groups of exceptional type. Although some of them are well known, we include them for completeness 相似文献