Reaction Model Research Articles

Solvent Exsolution and Liberation from Different Heavy Oil–Solvent Systems in Bulk Phases and Porous Media: A Comparison Study

In this paper, experimental and numerical studies were conducted to differentiate solvent exsolution and liberation processes from different heavy oil–solvent systems in bulk phases and porous media. Experimentally, two series of constant-composition-expansion (CCE) tests in a PVT cell and differential fluid production (DFP) tests in a sandpacked model were performed and compared in the heavy oil–CO2, heavy oil–CH4, and heavy oil–C3H8 systems. The experimental results showed that the solvent exsolution from each heavy oil–solvent system in the porous media occurred at a higher pressure. The measured bubble-nucleation pressures (Pn) of the heavy oil–CO2 system, heavy oil–CH4 system, and heavy oil–C3H8 system in the porous media were 0.24 MPa, 0.90 MPa, and 0.02 MPa higher than those in the bulk phases, respectively. In addition, the nucleation of CH4 bubbles was found to be more instantaneous than that of CO2 or C3H8 bubbles. Numerically, a robust kinetic reaction model in the commercial CMG-STARS module was utilized to simulate the gas exsolution and liberation processes of the CCE and DFP tests. The respective reaction frequency factors for gas exsolution (rffe) and liberation (rffl) were obtained in the numerical simulations. Higher values of rffe were found for the tests in the porous media in comparison with those in the bulk phases, suggesting that the presence of the porous media facilitated the gas exsolution. The magnitudes of rffe for the three different heavy oil–solvent systems followed the order of CO2 > CH4 > C3H8 in the bulk phases and CH4 > CO2 > C3H8 in the porous media. Hence, CO2 was exsolved from the heavy oil most readily in the bulk phases, whereas CH4 was exsolved from the heavy oil most easily in the porous media. Among the three solvents, CH4 was also found most difficult to be liberated from the heavy oil in the DFP test with the lowest rffl of 0.00019 min−1. This study indicates that foamy-oil evolution processes in the heavy oil reservoirs are rather different from those observed from the bulk-phase tests, such as the PVT tests.

Combined treatment of All-trans retinoic acid with Tamoxifen suppresses ovarian cancer.

Ovarian cancer is a malignant tumor of the female reproductive system, and its mortality rate is as high as 70%. Estrogen receptor α (ERα)-positive ovarian cancer accounted for most of all ovarian cancer patients. ERα can promote the growth and proliferation of tumors. The combined effect of All-trans retinoic acid (ATRA) and tamoxifen was obtained by the combination screening of tamoxifen and compound library by MTS. In addition, colony formation assay, flow cytometry analysis, immunofluorescence staining, quantitative real-time polymerase chain reaction (PCR), western blot, and tumor xenotransplantation models were used to further evaluate the efficacy of tamoxifen and ATRA in vitro and in vivo for ER-α-positive ovarian cancer. In our study, we found that All-trans retinoic acid (ATRA) can cooperate with tamoxifen to cause cell cycle arrest and apoptosis and inhibit ERα-positive ovarian cancer in vivo and in vitro. Further exploration of the mechanism found that ATRA can Inhibit genes related to the ERα signaling pathway, enhance the sensitivity of ERα-positive ovarian cancer cells to tamoxifen, and ascertain the effectiveness of tamoxifen and ATRA as treatments for ovarian cancer with an ERα-positive status. Combination of ATRA and tamoxifen is a new way for the treatment of ERα-positive ovarian cancer.

Carbon Atom Condensation on NH3-H2O Ices. An Alternative Pathway to Interstellar Methanimine and Methylamine.

The recent discovery of the nature and behavior of carbon atoms interacting with interstellar ices has prompted a number of investigations on the chemistry initiated by carbon accretion on icy interstellar dust. In this work, we expand the range of processes promoted by carbon accretion to the chemistry initiated by the interaction of this atom with ammonia (NH3) using quantum chemical calculations. We found that carbon addition to the ammonia molecule forms a rather stable radical, CNH3, that is easily hydrogenated. The complete hydrogenation network is later studied. Our calculations reveal that while conversion to simpler molecules like HCN and HNC is indeed a possible outcome promoted by H-abstraction reactions, methylamine is also easily formed (CH3NH2). In fact, the stability of methylamine against hydrogen abstraction makes this molecule the preferred product of the reaction network. Our results serve as a stepping stone toward the accurate modeling of C-addition reactions in realistic astrochemical kinetic models.

Chemical insight into thermal degradation, chemical kinetics, and thermodynamics behavior of sewage sludge through thermogravimetry and Fourier transform infrared analysis

Pyrolysis emerges as a promising path for sewage sludge (SS) management and value creation by producing compounds with enhanced utility. This study focuses on a comprehensive analysis of the thermal decomposition of SS using thermogravimetric analysis (TGA) and Fourier transform infrared spectrometry (FTIR). The TGA and FTIR were employed to evaluate the pyrolysis behavior, kinetics, and characteristics during pyrolysis of SS. The process revealed three distinct stages: 1st stage ranged between 30–185 °C with the removal of moisture, 2nd stage saw devolatilization of SS in the range of 185–595 °C, and the 3rd stage was mainly the formation of char in the temperature range of 595–900 °C. Pyrolysis kinetics, reaction mechanisms, and thermodynamic properties were extensively investigated at three different heating rates of 10, 20, and 30 °C /min. It was observed that with the temperature rise, the decomposition rate also increased rapidly, notably for the heating rate of 30 °C/min. Using Flynn-Wall-Ozawa, Kissinger-Akahira-Sunose, Starink, and Tang methods, activation energies for SS pyrolysis were estimated for α in the range of 0.2–0.85, and the average value for that range was found to be 84.72, 92.29, 91.99, and 91.76 kJ/mol, respectively for different iso-conversional methods. The chemical kinetics analysis through Coats-Redfern methods identified that 3-D diffusion-reaction mechanisms have the highest coefficient of determination among the other models. Criado z-master plot emphasizes the prevalence of Avrami-Erofeev (A4) as the bestsuited reaction model in combination with α, providing a detailed examination that illuminates the complex processes and mechanisms inherent in the pyrolysis of sewage sludge.

Hydrogen Tunneling Exhibiting Unexpectedly Small Primary Kinetic Isotope Effects.

Probing quantum mechanical tunneling (QMT) in chemical reactions is crucial to understanding and developing new transformations. Primary H/D kinetic isotopic effects (KIEs) beyond the semiclassical maximum values of 7‒10 (room temperature) are commonly used to assess substantial QMT contributions in one-step hydrogen transfer reactions, because of the much greater QMT probability of protium vs. deuterium. Nevertheless, we report here the discovery of a reaction model occurring exclusively by H-atom QMT with residual primary H/D KIEs. A 2-hydroxyphenylnitrene, generated in N2 matrix, was found to isomerize to an imino-ketone via sequential (domino) QMT involving anti to syn OH-rotamerization (rate determining step) and [1,4]-H shift reactions. These sequential QMT transformations were also observed in the OD-deuterated sample, and unexpected primary H/D KIEs between 3 and 4 were measured at 3 to 20 K. Analogous residual primary H/D KIEs were found in the anti to syn OH-rotamerization QMT of 2-cyanophenol in a N2 matrix. Evidence strongly indicates that these intriguing isotope-insensitive QMT reactivities arise due to the solvation effects of the N2 matrix medium, putatively through coupling with the moving H/D tunneling particle. Should a similar scenario be extrapolated to conventional solution conditions, then QMT may have been overlooked in many chemical reactions.

Complex Droplet Microreactor for Highly Efficient and Controllable Esterification and Cascade Reactions.

A highly efficient complex emulsion microreactor has been successfully developed for multiphasic water-labile reactions, providing a powerful platform for atom economy and spatiotemporal control of reaction kinetics. Complex emulsions, composing a hydrocarbon phase (H) and a fluorocarbon phase (F) dispersed in an aqueous phase (W), are fabricated in batch scale with precisely controlled droplet morphologies. A biphasic esterification reaction between 2-bromo-1,2-diphenylethane-1-ol (BPO) and perfluoro-heptanoic acid (PFHA) is chosen as a reversible and water-labile reaction model. The conversion reaches up to 100% under mild temperature without agitation, even with nearly equivalent amounts of reactants. This efficiency surpasses all reported single emulsion microreactors, i.e., 84~95%, stabilized by various emulsifiers with different catalysts, which typically necessitate continuous stirring, a high excess of one reactant, and/or extended reaction time. Furthermore, over 3 times regulation threshold in conversion rate is attained by manipulating the droplet morphologies, including size and topology, e.g., transition from completely engulfed F/H/W double to partially engulfed (F+H)/W Janus. Addition-esterification, serving as a model for triple phasic cascade reaction, is also successfully implemented under agitating-free and mild temperature with controlled reaction kinetics, demonstrating the versatility and effectiveness of the complex emulsion microreactor.

Verification and validation of detonation-shock-dynamics relations for explosives described by general equation of state and chemical reaction models

Detonation shock dynamics is a powerful method to model the behaviour of High Explosives (HE). However in order to use this method, the underlying relationship between the local radius of curvature and the detonation speed must be known. Previous work has developed methods to calculate this effect using simple, single-step Arrhenius and polytropic gas, models for the chemical reaction and the equation of state, respectively. In recent years, more complex models for both reaction rates and equations of state have been developed which show better agreement with experimental data than these simple models, especially when considering condensed phase explosives.. This work presents the governing equations for solving these problems in a way that is generalised to use arbitrary equations of state as well as reaction models which may have more than a single step and multiple product species. This implementation is verified against exact solutions, demonstrating that the equations were implemented properly. The verified algorithm is then validated against experimental data and high fidelity simulations, showing that it is able to make accurate predictions in a regime where the underlying assumptions of the governing equations are valid. This approach has many applications: from creating equivalent detonation shock dynamics models for existing reactive burn calibrations for HE; to developing new functional forms and calibrations of reactive burn models for condensed phase high explosives.

A role for conformational changes in enzyme catalysis

The role played by conformational changes in enzyme catalysis is controversial. In addition to examining specific enzymes, studying formal models can help identify the conditions under which conformational changes promote catalysis. Here, we present a model demonstrating how conformational changes can break a generic trade-off due to the conflicting requirements of successive steps in catalytic cycles, namely high specificity for the transition state to accelerate the chemical transformation and low affinity for the products to favor their release. The mechanism by which the trade-off is broken is a transition between conformations with different affinities for the substrate. The role of the effector that induces the transition is played by a substrate “handle,” a part of the substrate that is not chemically transformed but whose interaction with the enzyme is nevertheless essential to rapidly complete the catalytic cycle. A key element of the model is the formalization of the constraints causing the trade-off that the presence of multiple states breaks, which we attribute to the strong chemical similarity between successive reaction states—substrates, transition states, and products. For the sake of clarity, we present our model for irreversible one-step unimolecular reactions. In this context, we demonstrate how the different forms that chemical similarities between reaction states can take impose limits on the overall catalytic turnover. We first analyze catalysts without internal degrees of freedom and then show how two-state catalysts can overcome their limitations. Our results recapitulate previous proposals concerning the role of conformational changes and substrate handles in a formalism that makes explicit the constraints that elicit these features. In addition, our approach establishes links with studies in the field of heterogeneous catalysis, where the same trade-offs are observed and where overcoming them is a well-recognized challenge.

Deformation in the wrinkle–crease transformation

We investigate deformation in the wrinkle–crease transformation to reveal the missing link between the wrinkling and creasing instabilities, which occur on the surface of elastomers under compression. Plane-strain finite element (FE) analysis is performed by combining a nonlinear perturbation approach to find two bifurcated solutions for the flat surface in a metastable state. The first solution is the stable deformation path for crease evolution, and the second solution is the previously unknown unstable deformation path from wrinkling to creasing. The two deformation paths are not independent, and they are connected at the critical strain for creasing εC. The resulting deformation at εC acts as a precursive deformation to cause creasing. Although the unstable path is initiated by the wrinkling instability as a bifurcation, the creasing instability (i.e., εC) is interpreted as the singular point at which the unstable path switches to the stable path. A chain reaction model is developed to describe the mechanism and deformation of the wrinkle–crease transformation, and it shows good agreement with the FE prediction within an inevitable limitation of FEs.

Nano-roughness effect on the interfacial thermal oxidation and surface catalytical recombination characteristics for silicon carbide based materials under non-equilibrium flow

With the rapid development of high-speed aircraft, the demanding for light, strong, reliable and high temperature resistive thermal protection material (TPM) is becoming urgent. High temperature material interface, such as silicon carbide (SiC) ceramic matrix composite, has received strong interest recently due to its high mechanical and thermochemical stability. For reactive interface development with nano-roughness under extremely hyperthermal non-equilibrium flow conditions for TPM applications, however, has not been reported yet. This work performs a systematic reactive molecular dynamics (RMD) study of the SiC surface morphology effect withstanding hyperthermal atomic oxygen (AO) impact via a gas–solid interface reaction model. The results show that a self-healing trend of the defect-rich silicon carbide surface with original nano-roughness is revealed towards a flatter interface accompanying with the oxidation process. The surface catalytic recombination coefficient is more sensitivity to the surface defects when wall temperature Tw > 500 K. Nano-roughness structure can also vary the main thermochemical reaction path at the thermochemical reactive interface: For the nano-groove surface model, the thermal oxidation reaction becomes dominant, while more pronounced surface catalytic recombination characteristics are revealed for the flat surface model. The mechanisms of roughness effect, surface temperature and gas impacting angle on the surface catalytic recombination, surface oxidation, and interface evolution are revealed, which advance our microscopic understanding of SiC interfacial performance with nano-roughness under non-equilibrium flow conditions.

One-pot strategy for the preparation of nanoparticles grafted with bimodal polymers: An in-silico insight

Polymer nanocomposites composed of polymer-grafted nanoparticles (NPs) have garnered significant interest due to their diverse functional applications in various domains. The emerging concept of bimodal polymer brushes within the grafting-nanoparticle framework offers control over interfacial entropic and enthalpic interactions. Here, we introduce a novel one-pot strategy that integrates “grafting-to” and “grafting-from” methods to create polymer-grafted bimodal NPs. Utilizing coarse-grained molecular dynamics simulations with a stochastic reaction model, we explore the factors influencing grafting density and polydispersity in these NPs. Our findings demonstrate that this one-pot strategy achieves a polydispersity similar to the two-step “grafting-from then grafting-to” process, while attaining a moderate grafting density comparable to the “grafting-to then grafting-from” approach. Consequently, we analyze factors such as “grafting-from” reaction rates, and initial feeding ratios, step-addition techniques which collectively influence the final grafting density and polydispersity index within this one-pot strategy. This comprehensive investigation enhances our understanding of the kinetics behind synthesizing bimodal polymer-grafted NPs and offers insights for designing polymer-based nanocomposites with improved performance.

A detailed kinetic submechanism for OH[formula omitted] chemiluminescence in hydrogen combustion revisited. Part 2

In this series of two papers, we present a novel physically sound kinetic submechanism aimed at modeling the formation and decay of chemiluminescent (electronically excited) OH∗ molecules in the ignition and combustion of hydrogen and hydrogen-based mixtures over a wide range of temperatures and pressures. The present Part describes the construction of this detailed reaction submechanism based on the groundwork and findings of the preceding paper. In so doing, we relied both on critical evaluation of known and at times conflicting experimental and theoretical data on the elementary reaction kinetics of OH∗ and on our quantum chemical calculations and rate constant estimates for the key processes. The kinetic model under development was validated against the representative dataset of the observed OH(A2Σ+→X2Π) chemiluminescent emission accompanying the high-temperature (post-shock) oxidation of various H2-containing mixtures. To improve its performance against the collected OH∗ emission data, the rate constants of some reactive and quenching processes, to which the OH∗ kinetics is the most sensitive and for which there is a particular uncertainty, were jointly varied within the limits imposed by theoretical considerations and/or the scatter in the available experimental evidence. Thus, by refining the rate constants of these elementary processes, we obtained a reasonable reaction submechanism for OH∗ that describes the known experimental data better than previous models.Novelty and significance statement Although ultraviolet OH∗ chemiluminescence as an optical signature of the combustion process and the underlying chemistry is known to provide unique capabilities for combustion diagnostics, the development of the detailed reaction mechanisms intended for quantitative interpretation of the OH∗ emission measurements has now almost stagnated. Indeed, existing kinetic models contain a discouragingly small number of elementary processes and, apparently, do not account for the full variety of possible reaction pathways of OH∗ formation and depletion. Therefore, in this serial work, we have intended to revise the current ideas about the kinetics of OH∗ production and consumption during ignition and combustion and focused first on the OH∗ kinetics in a reacting H2/O2/Ar/N2 mixture. The principal outcome of this Part of the series is a new physically based kinetic submechanism aimed at modeling the formation and decay of electronically excited OH∗ molecules in the ignition and combustion of hydrogen and hydrogen-containing mixtures. Its incorporation into any conventional kinetic model of hydrogen oxidation enables quantitative interpretation of the OH(A2Σ+−X2Π) chemiluminescent emission observed experimentally in flames and shock-heated reacting flows with an accuracy higher than that of previous analogous mechanisms. No less importantly, the rate constant approximations for a number of individual elementary processes with OH∗, recommended here based on the critical review of literature data and on our quantum chemical calculations, are also of independent interest for the kinetics of electronically excited OH∗ particles. Finally, the OH∗ reaction subset we suggested for hydrogen flames can form the basis of more complex OH∗ chemiluminescence modeling reaction mechanisms for other fuels and fuel compositions.

Numerical solution of Fisher’s equation through the application of Haar wavelet collocation method

This research article presents algorithm that employs the Haar wavelet collocation method (HWCM) to solve the convection diffusion reaction (CDR) model, specifically Fisher’s equation (F.E.). The proposed method is suitable for addressing both linear and nonlinear problems. The Haar wavelet method is a numerical technique that utilizes wavelet basis functions to provide an approximation of the solution for the Fisher’s equations. Additionally, a forward difference scheme is utilized to approximate the time derivative while the highest order space derivative is replaced by Haar function. The performance of the technique is demonstrated through some examples investigated in this study. The maximum absolute errors are computed for varying numbers of collocation points. The HWCM provides superior accuracy, flexibility, convenience, and computational efficiency compared to alternative methods.

Psychometric Test for Medical Consultancy System

Abstract: Preliminary investigations delve into the possibility of employing chatbots in psychiatric therapy to aid behavior modification through assessments and chatbot interventions. Nevertheless, these platforms overlook the mental conditions of users, neglecting interviews, continuous surveillance, or ethical factors. We propose that enhancing emotion detection could boost user contentment among individuals seeking mental health assistance. Our suggestion encompasses an interactive psychiatric counseling service employing sophisticated natural language comprehension and multimodal emotion detection. This method permits ongoing and delicate observation of emotional fluctuations. Moreover, an instance-oriented reaction model, integrating moral discernment, facilitates suitable clinical reactions in psychiatric consultations.

Investigation of the Leaching Kinetics of Zinc from Smithsonite in Ammonium Citrate Solution

In this study, the response surface method is used to develop a model for analyzing and optimizing zinc leaching experiments. An investigation into the leaching kinetics of smithsonite in ammonium citrate solution is also conducted. A model of kinetics is studied in order to represent these effects. The experimental data show that an increase in the solution temperature, concentration, and stirring speed has a positive impact on the leaching rate, while an increase in the particle size has a negative impact on it. The optimal experimental conditions consist of a leaching temperature of 70 °C, ammonium citrate concentration of 5 mol/L, particle size of 38 µm, and rotational speed of 1000 rpm. Under these optimal conditions, the leaching rate of zinc from smithsonite is 83.51%. It is speculated that the kinetic model will change when the temperature is higher than 60 °C. When the temperature is lower than 60 °C, the leaching process is under the control of the shrinking core model of the surface chemical reactions. The calculated activation energy of the leaching reaction is equal to 42 kJ/mol. The model of the leaching process can be described by the following equation: 1−1−x1/3=k0⋅(C)0.6181⋅r0−0.5868⋅SS0.6901exp⁡−42/RT]t. This demonstrates that an ammonium citrate solution can be used in the leaching process of zinc in smithsonite as an effective and clean leaching agent.

Chemical looping reforming of the micromolecular component from biomass pyrolysis via Fe2O3@SBA-16

AbstractTo solve the problems of low gasification efficiency and high tar content caused by solid–solid contact between biomass and oxygen carrier in traditional biomass chemical looping gasification process. The decoupling strategy was adopted to decouple the biomass gasification process, and the composite oxygen carrier was prepared by embedding Fe2O3 in molecular sieve SBA-16 for the chemical looping reforming process of pyrolysis micromolecular model compound methane, which was expected to realize the directional reforming of pyrolysis volatiles to prepare hydrogen-rich syngas. Thermodynamic analysis of the reaction system was carried out based on the Gibbs free energy minimization method, and the reforming performance was evaluated by a fixed bed reactor, and the kinetic parameters were solved based on the gas–solid reaction model. Thermodynamic analysis verified the feasibility of the reaction and provided theoretical guidance for experimental design. The experimental results showed that the reaction performance of Fe2O3@SBA-16 was compared with that of pure Fe2O3 and Fe2O3@SBA-15, and the syngas yield was increased by 55.3% and 20.7% respectively, and it had good cycle stability. Kinetic analysis showed that the kinetic model changed from three-dimensional diffusion to first-order reaction with the increase of temperature. The activation energy was 192.79 kJ/mol by fitting. This paper provides basic data for the directional preparation of hydrogen-rich syngas from biomass and the design of oxygen carriers for pyrolysis of all-component chemical looping reforming.

Characterization and kinetic analysis of lignocellulosic and algal biochar combustion

The combustion characteristics of biochar obtained from barley straw (BS) and brown algae (BA) are explored. Four different heating rates are utilized to determine the respective activation energies. A master plot analysis is used to identify the appropriate reaction model. The results show that the activation energies vary in the ranges of 6.86–48.36 and 46.34–77.51 kJ mol−1 for BS and BA biochar combustion, respectively. As the heating rate increases, most of the combustion characteristic parameters increase, while the combustion stability index decreases. These observations help provide a deeper understanding of the combustion of lignocellulosic and algal biomass-derived biochar.

Corrosion resistance of Nb and NbTi alloy predicted by hydrogen evolution reaction models modified with Langmuir isotherm adsorption theory

Langmuir isotherm adsorption theory is involved in the conventional model to predict the corrosion resistance of Nb and Nb alloys. It is illustrated that the anti-corrosion properties of Nb are dependent on the crystal plane, pH values and solution temperature. Nb(110) plane with the lowest Esurf/ρ and the highest Eesc present the slower dissolution of Nb atoms, and then exhibits the best anti-corrosion performance. Alloying with Cr, Cu, Mo, Ti and Ta destroys the stability of Nb(110) plane and thus degrades the corrosion resistance performances. Moreover, the anti-corrosion performance is improved with increasing pH values because of the decreasing coverage of H+ ions. The escape rate of Nb atoms will be accelerated at the elevating temperature, and thus the anti-corrosion performance be degraded. Therefore, an appropriate design of coating texture and solution environment could improve the anti-corrosion performances of bipolar plates.

Modeling and experimental analysis of CO2 methanation reaction using Ni/CeO2 monolithic catalyst.

In this study, the effect of the cell density of monolithic catalysts was investigated and further mathematically modeled on cordierite supports used in CO2 methanation. Commercial cordierite monoliths with 200, 400, and 500 cpsi cell densities were coated by immersion into an ethanolic suspension of Ni/CeO2 active phase. SEM-EDS analysis confirmed that, owing to the low porosity of cordierite (surface area < 1 m2g-1), the Ni/CeO2 diffusion into the walls was limited, especially in the case of low and intermediate cell density monoliths; thus, active phase was predominantly loaded onto the channels' external surface. Nevertheless, despite the larger exposed surface area in the monolith with high cell density, which would allow for better distribution and accessibility of Ni/CeO2, its higher macro-pore volume resulted in some introduction of the active phase into the walls. As a result, the catalytic evaluation showed that it was more influenced by increments in volumetric flow rates. The low cell density monolith displayed diffusional control at flow rates below 500mLmin-1. In contrast, intermediate and high cell density monoliths presented this behavior up to 300mLmin-1. These findings suggest that the interaction reactants-catalyst is considerably more affected by a forced non-uniform flow when increasing the injection rate. This condition reduced the transport of reactants and products within the catalyst channels and, in turn, increased the minimum temperature required for the reaction. Moreover, a slight diminution of selectivity to CH4 was observed and ascribed to the possible formation of hot spots that activate the reverse water-gas shift reaction. Finally, a mathematical model based on fundamental momentum and mass transfer equations coupled with the kinetics of CO2 methanation was successfully derived and solved to analyze the fluid dynamics of the monolithic support. The results showed a radial profile with maximum fluid velocity located at the center of the channel. A reactive zone close to the inlet was obtained, and maximum methane production (4.5molm-3) throughout the monolith was attained at 350°C. Then, linear streamlines of the chemical species were developed along the channel.

Tripeptide-Catalyzed Asymmetric Michael Addition Reaction of β-Nitrostyrenes with Cyclohexanone

AbstractA tripeptide catalyst derived from natural l-amino acids was employed in the reaction of β-nitrostyrenes with cyclohexanone, serving as a model for the asymmetric Michael addition reaction. The reaction was conducted in the presence of H-Pro-Tle-Gly-OH and 2-fluoro-4-chlorobenzoic acid as co-catalysts (each at 20 mol%) in DMF-H2O (5:1) at 0 °C for 3 days. This process yielded the desired Michael adducts with excellent efficiency and good stereoselectivity (up to 98% yield, up to 92% ee).