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111.
112.
A. N. Karaseva V. V. Karlin A. I. Konovalov V. F. Mironov Yu. Ya. Efremov D. R. Sharafutdinova O. V. Tsepaeva E. R. Yunusov 《Chemistry of Natural Compounds》2000,36(3):269-271
The acid composition of seed oil ofAmaranthus cruentus and the synthesis of their glycidyl and pyridinecontaining esters are studied. It is demonstrated that 67% of the total acids are C18-polyunsaturated linoleic and linolenic. A new method for preparing glycidyl esters of C18-unsaturated carboxylic acids is developed by reacting their salts with ECG in an aprotic medium to produce the corresponding glycidyl esters. The reaction of the glycidyl esters and pyridine salts with carboxylic and phosphonic acids produces the propanolpyridine esters of the acids that combine the properties of the acids and pyridinium salts and are promising in the search for biologically active compounds.A. E. Arbuzov Institute of Organic and Physical Chemistry, Kazan' Scientific Center, Russian Academy of Sciences. Translated from Khimiya Prirodnykh Soedinenii, No. 3, pp. 217–219, May–June, 2000. 相似文献
113.
Samuel Karlin Marcus Feldman 《International Journal of Mathematical Education in Science & Technology》2013,44(2):169-189
A principal area of applications of mathematical ideas is the study of population genetic systems. Such investigations have inspired the development of mathematical statistics, insights for certain classes of stochastic processes of diffusion type and intriguing algebraic structures. In this paper a series of simple mathematical models for evolutionary theory and inbreeding systems are set forth. Included are the Hardy‐Weinberg law and models of selection balance. We also treat several special inbreeding processes for selfing (self fertilization), sib mating, incompatibility systems and imprinting. Calculations of inbreeding coefficients using the notion of ‘identity by descent’ are made. Some classical simple stochastic models exposing the concept of genetic drift are highlighted. 相似文献
114.
On modern processors, data transfer exceeds floating-point operations as the predominant cost in many linear algebra computations. One tuning technique that focuses on reducing memory accesses is loop fusion. Determining the optimum amount of loop fusion to apply to a routine is difficult as fusion can both positively and negatively impact memory traffic. We present a model that accurately and efficiently evaluates how loop fusion choices affect data movement through the memory hierarchy. We show how to convert the model’s memory traffic predictions to runtime estimates that can be used to compare loop fusion variants. 相似文献
115.
Vladimir Karlin 《Flow, Turbulence and Combustion》2011,87(2-3):511-523
In this article the possibility of radiation heat transfer to trigger transition to detonation is studied. It is assumed that the premixed deflagration front is able to emit and the unburnt mixture to absorb radiation heat effectively. Under this assumption the ability of the flame to significantly preheat the unburnt mixture and to form a promoting temperature gradient is investigated. First, we estimate the temperature rise due to the radiation preheating of the unburnt mixture, when it is traveling through deep flame wrinkles. Subsequently, we carry out numerical simulations of premixed gaseous combustion in a tube. The simulations confirm the possibility of formation of promoting temperature gradients within flame folds and initiation of the detonation waves. They demonstrate the plausibility of the proposed mechanism of the deflagration to detonation transition. 相似文献
116.
Observation of a CuII2(μ‐1,2‐peroxo)/CuIII2(μ‐oxo)2 Equilibrium and its Implications for Copper–Dioxygen Reactivity
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Dr. Matthew T. Kieber‐Emmons Jake W. Ginsbach Dr. Patrick K. Wick Dr. Heather R. Lucas Dr. Matthew E. Helton Dr. Baldo Lucchese Prof. Masatatsu Suzuki Prof. Andreas D. Zuberbühler Prof. Kenneth D. Karlin Prof. Edward I. Solomon 《Angewandte Chemie (International ed. in English)》2014,53(19):4935-4939
Synthesis of small‐molecule Cu2O2 adducts has provided insight into the related biological systems and their reactivity patterns including the interconversion of the CuII2(μ‐η2:η2‐peroxo) and CuIII2(μ‐oxo)2 isomers. In this study, absorption spectroscopy, kinetics, and resonance Raman data show that the oxygenated product of [(BQPA)CuI]+ initially yields an “end‐on peroxo” species, that subsequently converts to the thermodynamically more stable “bis‐μ‐oxo” isomer (Keq=3.2 at ?90 °C). Calibration of density functional theory calculations to these experimental data suggest that the electrophilic reactivity previously ascribed to end‐on peroxo species is in fact a result of an accessible bis‐μ‐oxo isomer, an electrophilic Cu2O2 isomer in contrast to the nucleophilic reactivity of binuclear CuII end‐on peroxo species. This study is the first report of the interconversion of an end‐on peroxo to bis‐μ‐oxo species in transition metal‐dioxygen chemistry. 相似文献
117.
The reaction of p-substituted benzyl halides ((Y)BnX; X = Cl, Br, and I; Y = p-substituent, OMe, t-Bu, Me, H, F, Cl, and NO(2)) and copper(I) complexes supported by a series of (2-pyridyl)alkylamine ligands has been investigated to shed light on the mechanism of copper(I) complex mediated carbon-halogen bond activation, including ligand effects on the redox reactivity of copper(I) complexes which are relevant to the chemistry. For both the tridentate ligand (Phe)L(Pym2) [N,N-bis(2-pyridylmethyl)-2-phenylethylamine] and tetradentate ligand TMPA [tris(2-pyridylmethyl)amine] complexes, the C-C coupling reaction of benzyl halides proceeded smoothly to give corresponding 1,2-diphenylethane derivatives and copper(II)-halide complex products. Kinetic analysis revealed that the reaction obeys second-order kinetics both on the copper complex and the substrate; rate = k[Cu](2)[(Y)BnX](2). A reaction mechanism involving a dinuclear copper(III)-halide organometallic intermediate is proposed, on the basis of the kinetic results, including observed electronic effects of p-substituents (Hammett plot) and the rate dependence on the BDE (bond dissociation energy) of the C-X bond, as well as the ligand effects. 相似文献
118.
Chufan EE Verani CN Puiu SC Rentschler E Schatzschneider U Incarvito C Rheingold AL Karlin KD 《Inorganic chemistry》2007,46(8):3017-3026
With the established chemistry of bridged [(porphyrinate)FeIII-X-CuII(ligand)]n+ [X = O2- (oxo), OH- (hydroxo), O22- (peroxo)] complexes, we investigated the effect of cobalt ion substitution for copper or copper and iron. Thus, in this report, the generation and characterization of new mu-oxo, micro-hydroxo, and micro-peroxo (micro-X) assemblies of [(porphyrinate)MIII-X-CoII/III(TMPA)]n+ assemblies is described, where M = FeIII or CoIII and TMPA = tris(2-pyridylmethyl)amine. The mu-oxo complex [(F8TPP)FeIII-O-CoII(TMPA)]+ (1, F8TPP = tetrakis(2,6-difluorphenyl)porphyrinate) was isolated by an acid-base self-assembly reaction of a 1:1 mixture of (F8TPP)FeIII-OH and [CoII(TMPA)(MeCN)]2+ upon addition of triethylamine. The crystal structure of 1.2C4H10O proved the presence of an unsupported Fe-O-Co moiety; angleFe-O-Co = 171.6 degrees and d(Fe...Co) = 3.58 A. Complex 1 was further characterized by UV-vis (lambdamax = 437 (Soret) and 557 nm), 1H NMR [delta 40.6 (pyrrole-H), 8.8 and 8.7 (m-phenyl-H), 8.0 (p-phenyl-H), 4.4 (PY-4H), 2.6 (PY-3H), 1.0 (PY-5H), -1.1 (PY-6H), and -2.7 (TMPA-CH2-) ppm], electrospray ionization (ESI) and matrix-assisted laser desorption ionization time-of-flight (MALDI-TOF) mass spectrometric methods, Evans method NMR (microeff = 3.1), and superconducting quantum interference device (SQUID) susceptometry (J = -114 cm-1, S = 1). The micro-hydroxo analogue [(F8TPP)FeIII-(OH)-CoII(TMPA)]+ (2) [UV-vis lambdamax = 567 nm; delta 78 ppm (pyrrole-H); Evans NMR microeff = 3.7] was generated by addition of 1 equiv of triflic acid to 1. The protonation is completely reversible, and 1 is regenerated from 2 by addition of triethylamine. While (F8TPP)FeII/[CoII(TMPA)(MeCN)]2+/O2 chemistry does not lead to a stable micro-peroxo species, a dicobalt micro-peroxo complex [(TPP)CoIII-(O22-)-CoIII(TMPA)]2+ (3, TPP = meso-tetraphenylporphyrinate) forms from a reaction of O2 with a 1:1 mixture of the CoII precursor components at -80 degrees C [UV-vis lambdamax = 435 (Soret), 548, and 583 (weak) nm; silent EPR spectrum; diamagnetic NMR spectrum]. The oxygenation/deoxygenation equilibrium is reversible; warming solutions of 3 releases approximately 1 equiv of O2 and the reduced complexes are reformed. 相似文献
119.
Dioxygen Activation by a Macrocyclic Copper Complex Leads to a Cu2O2 Core with Unexpected Structure and Reactivity
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Dr. Isaac Garcia‐Bosch Dr. Ryan E. Cowley Daniel E. Díaz Maxime A. Siegler Prof. Wonwoo Nam Prof. Edward I. Solomon Prof. Kenneth D. Karlin 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(15):5133-5137
We report the CuI/O2 chemistry of complexes derived from the macrocylic ligands 14‐TMC (1,4,8,11‐tetramethyl‐1,4,8,11‐tetraazacyclotetradecane) and 12‐TMC (1,4,7,10‐tetramethyl‐1,4,7,10‐tetraazacyclododecane). While [(14‐TMC)CuI]+ is unreactive towards dioxygen, the smaller analog [(12‐TMC)CuI(CH3CN)]+ reacts with O2 to give a side‐on bound peroxo‐dicopper(II) species (SP), confirmed by spectroscopic and computational methods. Intriguingly, 12‐TMC as a N4 donor ligand generates SP species, thus in contrast with the previous observation that such species are generated by N2 and N3 ligands. In addition, the reactivity of this macrocyclic side‐on peroxo‐dicopper(II) differs from typical SP species, because it reacts only with acid to release H2O2, in contrast with the classic reactivity of Cu2O2 cores. Kinetics and computations are consistent with a protonation mechanism whereby the TMC acts as a hemilabile ligand and shuttles H+ to an isomerized peroxo core. 相似文献
120.