Eyring Equation Research Articles

A new biodiesel production by water addition to supercritical tert-butyl methyl ether using a plug flow reactor

The water addition to supercritical tert-butyl methyl ether for continuous biodiesel production from rapeseed oil has been carried out to promote an essential enhancement of biodiesel yield. We developed a new biodiesel production by supercritical tert-butyl methyl ether with water and evaluated process variables influence using response surface methodology to obtain an optimum condition. We found that the optimum condition was at water addition of 25 wt%, temperature of 300 °C, and pressure of 20 MPa at space time of 30 min to achieve 77.39 wt% of biodiesel yield. In addition, the reaction rate constants were determined by first-order reaction model. We suggested that water addition to the supercritical tert-butyl methyl ether accelerates reaction rate and diminishes activation energy since the water acts as a catalyst for the reaction. The thermodynamic parameters were calculated using Eyring-Polanyi equation based on the transition state theory. We found that the supercritical reaction was endothermic, endergonic, and non-spontaneous.

A model for the kinetics of high-temperature reactions between polydisperse volcanic ash and SO2 gas

AbstractRapid calcium diffusion occurs in rhyolitic volcanic ash particles exposed to hot SO2 atmospheres. Such chemical transport is important immediately following fragmentation, during proximal transport in eruption plumes and during percolative gas transport through a permeable volcanic edifice. Here we analyze published results of experiments designed to constrain the kinetics of this process. The experiments involve crushed rhyolitic glass particles tumbled in SO2-bearing atmospheres at a wide range of relevant temperatures. We find that the particle-gas reaction is fed by calcium diffusion from the bulk to the particle surfaces where calcium-sulfate crystals grow. The calcium flux is accommodated by local iron oxidation state changes. This process results in time-dependent concentrations of surface calcium that are leachable in aqueous solutions. Those leachate concentrations represent a proxy for the diffusive flux of Ca2+ out of the particle to form the surface deposits. We formulate a mathematical framework to convolve the starting particle size distributions with the solution to Fickian one-dimensional diffusion to find a weighted polydisperse result. Using this framework, we minimize for a temperature-dependent calcium diffusivity and compare our results with published calcium diffusivity data. We demonstrate that calcium diffusivity in rhyolite can be decomposed into two regimes: (1) a high-temperature regime in which the diffusivity is given by the Eyring equation and (2) a low-temperature regime more relevant to rhyolite volcanism and these gas-ash reactions. As a further test of our model, we compare the output against spatially resolved data for the calcium gradients in the experimental particles. Our analysis suggests that surface reaction rates are rapid compared with the diffusion of calcium from the particle to the surface, such that full diffusion models must be solved to predict the rhyolite-SO2 reaction. We conclude by suggesting how this framework could be used to make quantitative predictions of sulfur budgets and iron oxidation during rhyolitic eruptions.

Mechanistic Insight into the O2 Evolution Catalyzed by Copper Complexes with Tetra- and Pentadentate Ligands

The mononuclear complexes ([(bztpen)Cu] (BF4)2 (bztpen = N-benzyl-N,N',N'-tris (pyridin-2-yl methyl ethylenediamine))) and ([(dbzbpen)Cu(OH2)] (BF4)2 (dbzbpen = N,N'-dibenzyl-N,N'-bis(pyridin-2-ylmethyl) ethylenediamine)) have been reported as water oxidation catalysts in basic medium (pH = 11.5). We explore the O2 evolution process catalyzed by these copper catalysts with various ligands (L) by applying the first-principles molecular dynamics simulations. First, the oxidation of catalysts to the metal-oxo intermediates [LCu(O)]2+ occurs through the proton-coupled electron transfer (PCET) process. These intermediates are involved in the oxygen-oxygen bond formation through the water-nucleophilic addition process. Here, we have considered two types of oxygen-oxygen bond formation. The first one is the transfer of the hydroxide of the water molecule to the Cu═O moiety; the proton transfer to the solvent leads to the formation of the peroxide complex ([LCu(OOH)]+). The other is the formation of the hydrogen peroxide complex ([LCu(HOOH)]2+) by the transfer of proton and hydroxide of the water molecule to the metal-oxo intermediate. The formation of the peroxide complex requires less activation free energy than hydrogen peroxide formation for both catalysts. We found two transition states in the well-tempered metadynamics simulations: one for proton transfer and another for hydroxide transfer. In both cases, the proton transfer requires higher free energy. Following the formation of the oxygen-oxygen bond, we study the release of the dioxygen molecule. The formed peroxide and hydrogen peroxide complexes are converted into the superoxide complex ([LCu(OO)]2+) through the transfer of proton, electron, and PCET processes. The superoxide complex releases an oxygen molecule upon the addition of a water molecule. The free energy of activation for the release of the dioxygen molecule is lesser than that of the oxygen-oxygen bond formation. When we observe the entire water oxidation process, the oxygen-oxygen bond formation is the rate-determining step. We calculated the rates of reaction by using the Eyring equation and found them to be close to the experimental values.

Thermal antioxidative kinetics of sesamol in triacylglycerols and fatty acid methyl esters of sesame, olive, and canola oils

AbstractOxidation kinetics of the triacylglycerols (TAGs) and fatty acid methyl esters (FAMEs) of sesame, olive, and canola oils were studied in the presence of the different concentrations of sesamol (0.1%–0.16%) at 60, 80, and 100°C. Sesamol increased the temperature coefficient, TC, and Q10 number of the TAGs more significantly compared to the FAMEs. All the sesamol‐added TAG and FAME systems, respectively, of the olive, canola, and sesame oils, respectively, exerted increased values of the Arrhenius (activation energy, Ea, and frequency factor, A) and Eyring (enthalpy, ΔH++, and entropy, ΔS++) equation parameters. Sesamol improved the Gibbs free energy (ΔG++) of the activated complex formation in the canola, sesame, and olive systems, respectively, and the effect was greater in the FAMEs.

A theoretical approach for the acylation/deacylation mechanisms of avibactam in the reversible inhibition of KPC-2.

Klebsiella pneumoniae carbapenemase (KPC-2) is the most commonly encountered class A β-lactamase variant worldwide, which confer high-level resistance to most available antibiotics. In this article we address the issue by a combined approach involving molecular dynamics simulations and hybrid quantum mechanics/molecular mechanics calculations. The study contributes to improve the understanding, at molecular level, of the acylation and deacylation stages of avibactam involved in the inhibition of KPC-2. The results show that both mechanisms, acylation and deacylation, the reaction occur via the formation of a tetrahedral intermediate. The formation of this intermediate corresponds to the rate limiting stage. The activation barriers are 19.5 kcal/mol and 23.0 kcal/mol for the acylation and deacylation stages, respectively. The associated rate constants calculated, using the Eyring equation, are 1.2 × 10−1 and 3.9 × 10−4 (s−1). These values allow estimating a value of 3.3 × 10−3 for the inhibition constant, in good agreement with the experimental value.Supplementary InformationThe online version contains supplementary material available at 10.1007/s10822-021-00408-3.

Prediction of real tensile properties using extrapolations from atomistic simulations; An assessment on thermoplastic starch

Atomistic molecular dynamics (MD) simulations can be used to predict mechanical properties, such as stiffness and strength, for polymers. A concern is unavoidably high strain rates in simulations compared with those in physical experiments. To quantitatively capture the mechanical properties of the ‘real’ material, i.e., to predict absolute values rather than just qualitative trends, extrapolation to realistic strain rates is required. In this study, different strain-rate extrapolation strategies involving time-temperature shifting with the Williams-Landel-Ferry equation (above Tg) and the Eyring equation (below Tg) were evaluated, using thermoplastic starch as an example. MD simulations were first used to compute the stiffness and strength at three (high) strain rates over a wide range of temperatures. The mechanical MD data were then horizontally time-temperature shifted, resulting in master curves with strain-rate (x-axis) versus mechanical properties (y-axis). The precision in the prediction of experimental data was quite good in several cases, but was dependent on the extrapolation method and the specific thermoplastic starch system. A notable finding was that the simulations could be simplified using fewer simulation strain rates and temperatures. The extrapolation techniques used here are expected to be valid for other polymer systems, but this remains to be validated.

Kinetic modeling of ethyl carbamate formation from urea in Huangjiu during storage

Ethyl carbamate (EC) is a potential carcinogen widely found in various fermented foods and beverages, including Huangjiu (Chinese rice wine). Urea is the main precursor of ethyl carbamate in Huangjiu and the ethyl carbamate concentration increases gradually during storage. In this work, the changes of urea and EC content were investigated during the storage of Huangjiu under different conditions. The results indicated that urea hydrolysis is the dominant mechanism in urea consumption during storage. Then the kinetic models of urea consumption and EC formation were established based on the Arrhenius equation and Eyring equation, respectively. The prediction results of urea and EC concentrations based on these two models were consistent with experimental data, while the model based on the Eyring equation gave a better performance. The corresponding urea control indicators for Huangjiu with different alcohol concentrations under different storage conditions and specific EC benchmark limits can be calculated based on the model. The urea concentration of Huangjiu should be less than 2 mg/L to have a low risk for EC to exceed the standard of 100 μg/L after storage. Low-temperature storage can slow down and reduce the production of EC. These results are helpful to solve critical problems such as content prediction of urea and EC, condition control for storage and limit standards for EC in Huangjiu.

Improving the accuracy of the Eyring equation by pseudo‐ideal solution model to predict the viscosity of the mono‐ethanol amine‐[Bmim] PF6 ionic liquid blends in a CO2 capturing pilot plant

AbstractThe purpose of the present study was to propose a new simulation model for calculation of the viscosity of the mono‐ethanol amine‐ionic liquid (MEA‐IL) solvent in the CO2‐capturing pilot plant. To do so, a combination of the pseudo‐ideal solution model (PISM) and Eyring's mixture viscosity equation was implemented in MATLAB. Moreover, the various thermodynamic models were used to calculate viscosity, using solvent containing MEA‐IL in the high CO2 feed gas. The present study determined the viscosities of the MEA‐IL blends at different concentrations and various temperatures in the CO2 capturing pilot plant. The results were comparable to those obtained from the Eyring‐PISM model, Eyring‐Wilson method, Cheng and Meisen a previous study equation, and the Aspen Plus and Promax with electrolyte non‐random two‐liquid model that presented the actual viscosity values of the liquid solutions. The calculated solvent viscosity values with the Eyring‐PISM model at different temperature profiles were achieved using an average absolute deviation (AAD) of about 1.164% and 1.422% in absorber and desorber for solvent (MEA = 27 wt% and IL = 34.2 wt%) and 1.578% and 1.868% in absorber and desorber for solvent (MEA = 29 wt% and IL = 37.12 wt%), respectively. The consideration of a suitable model for the determination of viscosity has a significant role in energy consumption in the CO2‐capturing pilot plant. The estimated energy consumption with the Eyring‐PISM model was achieved using an AAD of about 0.652% for solvent (MEA = 27 wt% and IL = 34.2 wt%) and 0.502% for solvent (MEA = 29 wt% and IL = 37.12 wt%), respectively. The results obtained from the Eyring‐PISM simulation model using the experimental data revealed a high degree of accuracy.

A New Compromise Design Plan for Accelerated Failure Time Models with Temperature as an Acceleration Factor

An accelerated life test of a product or material consists of the observation of its failure time when it is subjected to conditions that stress the usual ones. The purpose is to obtain the parameters of the distribution of the time-to-failure for usual conditions through the observed failure times. A widely used method to provoke an early failure in a mechanism is to modify the temperature at which it is used. In this paper, the statistically optimal plan for Accelerated Failure Time (AFT) models, when the accelerated failure process is described making use of Arrhenius or Eyring equations, was calculated. The result was a design that had only two stress levels, as is common in other AFT models and that is not always practical. A new compromise plan was presented as an alternative to the widely used “4:2:1 plan”. The three-point mixture design proposed specified a support point in the interval that was optimal for the estimation of the parameters in AFT models, rather than simply the middle point. It was studied in comparison to different commonly used designs, and it proved to have a higher D-efficiency than the others.

Synthesis and Characterization of Palladium Nanoparticles Immobilized on Modified Cellulose Nanocrystals as Heterogeneous Catalyst for Reduction of Nitroaromatic Compounds

AbstractThroughout the present research, cellulose nanocrystals (CNCs) have been modified with 3‐aminopropyltriethoxysilane (APTES) and also they have been exploited as the support for palladium nanoparticles (Pd NPs) using palladium complex. Moreover, Fourier Transform Infrared Spectroscopy(FT‐IR), Powder X‐ray Diffraction(PXRD), Field Emission Scanning Electron Microscopy(FE‐SEM), Energy Dispersive X‐ray Spectroscopy(EDS), Transmission Electron Microscopy(TEM), Inductively Coupled Plasma Optical Emission Spectroscopy(ICP‐OES) and Thermal gravimetric Analysis(TGA) were employed to characterize the Pd@CNC‐APTES nanocatalyst. The catalytic activity of the nanocatalyst has been investigated in the reduction of p‐Nitrophenol(p‐NP) and the other nitroaromatic compounds to the corresponding amine. Furthermore, the catalyst could be recycled four times without the considerable loss of Pd content and with a high level of p‐NP conversion. Using experimental results, thermodynamic parameters were calculated by Arrhenius and Eyring equations. The findings revealed the significant catalytic activity of Pd@CNC‐APTES nanocatalyst for the reduction of p‐NP and its derivatives by sodium borohydride(NaBH4) at room temperature.

Oxidative stability of ternary blends of vegetable oils: A chemometric approach

Unsaturated fatty acids in vegetable oil are prone to lipid oxidation that leads to rancidity, subsequently, the oil's nutritional value is compromised. Edible oils can be tailored to obtain an antioxidant-rich oil blend with better oxidative stability under accelerated storage conditions. In this research, the oxidative stability of the six oil blends containing rice bran oil (RBO: 50–75%), flaxseed oil (FO: 5–10%), peanut oil (PO: 20–40%) at different concentrations is assayed by Arrhenius and Eyring equations (R2 > 0.95, p < 0.05) under Rancimat test conditions (100, 110, 120, 130 °C @ air flowrate 20L/h). The activation energy (Ea), enthalpy change (ΔH), and entropy change (ΔS) of control and oil blends ranged from 74.28 to 93.59 kJ/mol-K, 71.05–90.36 kJ/mol, −41.87 to −100.19 J/mol-K, respectively. Addition of RBO increased tocopherol and oryzanol content in oil blends from 398 to 725 ppm, 0.7 to 1.0 %g, respectively. Hierarchical cluster analysis conferred that RBO-PO-FO: 75-20-5, had better oxidative stability (induction period, IP100: 21.34 h) comparable to RBO with a slower kinetic rate and can be used as a functional oil source. Better understanding of the influence of oil blending on quality traits was delineated by principal component analysis.

Structure, Function, and Thermal Adaptation of the Biotin Carboxylase Domain Dimer from Hydrogenobacter thermophilus 2-Oxoglutarate Carboxylase.

2-Oxoglutarate carboxylase (OGC), a unique member of the biotin-dependent carboxylase family from the order Aquificales, captures dissolved CO2 via the reductive tricarboxylic acid (rTCA) cycle. Structure and function studies of OGC may facilitate adaptation of the rTCA cycle to increase the level of carbon fixation for biofuel production. Here we compare the biotin carboxylase (BC) domain of Hydrogenobacter thermophilus OGC with the well-studied mesophilic homologues to identify features that may contribute to thermal stability and activity. We report three OGC BC X-ray structures, each bound to bicarbonate, ADP, or ADP-Mg2+, and propose that substrate binding at high temperatures is facilitated by interactions that stabilize the flexible subdomain B in a partially closed conformation. Kinetic measurements with varying ATP and biotin concentrations distinguish two temperature-dependent steps, consistent with biotin's rate-limiting role in organizing the active site. Transition state thermodynamic values derived from the Eyring equation indicate a larger positive ΔH⧧ and a less negative ΔS⧧ compared to those of a previously reported mesophilic homologue. These thermodynamic values are explained by partially rate limiting product release. Phylogenetic analysis of BC domains suggests that OGC diverged prior to Aquificales evolution. The phylogenetic tree identifies mis-annotations of the Aquificales BC sequences, including the Aquifex aeolicus pyruvate carboxylase structure. Notably, our structural data reveal that the OGC BC dimer comprises a "wet" dimerization interface that is dominated by hydrophilic interactions and structural water molecules common to all BC domains and likely facilitates the conformational changes associated with the catalytic cycle. Mutations in the dimerization domain demonstrate that dimerization contributes to thermal stability.

Microbial Decolorization of Reactive Black 5 by &lt;i&gt;Bacillus albus&lt;/i&gt; DD1 Isolated From Textile Waste Water Effluent: Kinetic and Thermodynamics Study and Decolorization Mechanism

Reactive Black 5 is one of the most widely used dye in textile and other industries. It is one of the significantly toxic azo dye which poses a serious threat to the environment when discharged into water bodies. A bacterial isolate showed 98% dye removal from aqueous medium within 38hours under optimum parameters pH 7, temperature 400C, in the presence of 1% yeast extract as a co-substrate, and 25% inoculum size at an initial concentration of 50mg/l. Kinetic and thermodynamic study revealed the decolorization reaction is a first order non- spontaneous reaction. The highest rate constant 0.0523 was observed at 318K. Further ΔH, ΔG and ΔS, Ea was estimated using Eyring Polanyi equation was 20.80KJ/mol, -0.1KJ/ Mk respectively. LC-MS analysis revealed that decolorization was due to degradation of RB5 by cleavage of azo-bond by the bacterium, with the formation of s 3,6,8-trihyroxynapthalene and phthalic acid as degradation products.

Kinetics of Electron Transfer Reaction between Co(II) and Chlorate Ions: Experimental and Modeling Study

This research article reports original experimental and modeling detail of kinetics of the electron transfer reaction between Co(II) and chlorate ions in acetic acid solution. Design of experiment methodology has been employed to elucidate the effects of temperature and initial concentrations of reactants on the rate of reaction. Levenberg-Marquardt method has been used to fit processed kinetic data (temperatures, initial concentrations of reactants, and concentrations and rates of production of Co(III)) on to various possible rate equations. This algorithm provides a proficient mean for compensating the capricious effects of the experimental process variables and results in the maximum likelihood estimates of the kinetic parameters. The most significant rate law has been selected, on the basis of statistical analyses of the residuals between the predicted and experimental rates. The analyses suggest that the intrinsic rate of reaction is proportional to first power of chlorate concentration but for Co(II) the order is fractional (0.7455 ≈ and#190;). The effect of temperature on the observed rate constant (precision = 0.02 %) is excellently described by the Arrhenius and Eyring equations and the sluggish nature of the reaction is clearly manifested by the high energy (andgt; 93 kJ/mol), negative entropy (-28.5286 J/mol-K) and very small equilibrium constant of activation. Further fairly negative standard entropy of activation shows there is usually considerable rearrangement of energy among various degrees of freedom during the formation of activated complex and proposes an associative mechanism for formation of the activated complex. This research is performed to develop a kinetic model for the electron transfer reaction between Co(II) and chlorate ion. As a result, a redox couple of Co(II)/Co(III) has been formed which is used as a potent oxidation catalyst in chemical industries.

Kinetics of Electron Transfer Reaction between Co(II) and Chlorate Ions: Experimental and Modeling Study

This research article reports original experimental and modeling detail of kinetics of the electron transfer reaction between Co(II) and chlorate ions in acetic acid solution. Design of experiment methodology has been employed to elucidate the effects of temperature and initial concentrations of reactants on the rate of reaction. Levenberg-Marquardt method has been used to fit processed kinetic data (temperatures, initial concentrations of reactants, and concentrations and rates of production of Co(III)) on to various possible rate equations. This algorithm provides a proficient mean for compensating the capricious effects of the experimental process variables and results in the maximum likelihood estimates of the kinetic parameters. The most significant rate law has been selected, on the basis of statistical analyses of the residuals between the predicted and experimental rates. The analyses suggest that the intrinsic rate of reaction is proportional to first power of chlorate concentration but for Co(II) the order is fractional (0.7455 ≈ and#190;). The effect of temperature on the observed rate constant (precision = 0.02 %) is excellently described by the Arrhenius and Eyring equations and the sluggish nature of the reaction is clearly manifested by the high energy (andgt; 93 kJ/mol), negative entropy (-28.5286 J/mol-K) and very small equilibrium constant of activation. Further fairly negative standard entropy of activation shows there is usually considerable rearrangement of energy among various degrees of freedom during the formation of activated complex and proposes an associative mechanism for formation of the activated complex. This research is performed to develop a kinetic model for the electron transfer reaction between Co(II) and chlorate ion. As a result, a redox couple of Co(II)/Co(III) has been formed which is used as a potent oxidation catalyst in chemical industries.

Thermodynamic Properties of Rifampicin Redox Current Peaks in Human Blood Samples Using Nano-Sensor (Carbon Nanotubes / Glassy Carbon Electrode)

The cyclic voltammetric electrochemical technique was utilized to investigate the effect of different temperatures on the redox current peaks of rifampicin (RF), a drug commonly used to treat many diseases including tuberculosis (TB), in vitro for human blood medium. A modified working electrode of glassy carbon electrode (GCE) with carbon nanotube (CNT) (CNT / GCE) was used as a sensitive nano-sensor to evaluate the impact of temperature on the blood medium in the presence of RF ions. The results confirmed the presence of two oxidation and one reduction current peaks of RF in blood medium at 0.5, 1, and -0.5 V respectively. The redox current peaks of RF ions in blood medium were enhanced with increasing the temperature from 20 to 36oC. The activation energy (E*) values were determined by applying Arrhenius equation with oxidative and anti-oxidative peaks of Ea*(Ipa)= 9.252 and 11.026 kJ.mol-1.K-1,respectively. Other thermodynamic functions such as the change in each of activation Enthalpy (ΔH*), activation Gibbs energy (ΔG*) and activation Entropy (ΔS*) values were estimated using Eyring equation. The present results of the effects of different temperatures on the blood status in presence of RF lead to the explanation of the oxidative stress of the drug which used in an inflammatory of blood at different temperature.

Thermodynamic Properties of Rifampicin Redox Current Peaks in Human Blood Samples Using Nano-Sensor (Carbon Nanotubes / Glassy Carbon Electrode)

The cyclic voltammetric electrochemical technique was utilized to investigate the effect of different temperatures on the redox current peaks of rifampicin (RF), a drug commonly used to treat many diseases including tuberculosis (TB), in vitro for human blood medium. A modified working electrode of glassy carbon electrode (GCE) with carbon nanotube (CNT) (CNT / GCE) was used as a sensitive nano-sensor to evaluate the impact of temperature on the blood medium in the presence of RF ions. The results confirmed the presence of two oxidation and one reduction current peaks of RF in blood medium at 0.5, 1, and -0.5 V respectively. The redox current peaks of RF ions in blood medium were enhanced with increasing the temperature from 20 to 36oC. The activation energy (E*) values were determined by applying Arrhenius equation with oxidative and anti-oxidative peaks of Ea*(Ipa)= 9.252 and 11.026 kJ.mol-1.K-1,respectively. Other thermodynamic functions such as the change in each of activation Enthalpy (ΔH*), activation Gibbs energy (ΔG*) and activation Entropy (ΔS*) values were estimated using Eyring equation. The present results of the effects of different temperatures on the blood status in presence of RF lead to the explanation of the oxidative stress of the drug which used in an inflammatory of blood at different temperature.

Variable-temperature &amp;lt;sup&amp;gt;1&amp;lt;/sup&amp;gt;H-NMR Studies on Three C-glycosylflavones Exhibiting Rotational Isomerism

Rotational isomerism has been observed on some C-glycosyl flavonoids with special chemical strutures. It may bring rotamers arising from restricted rotation about one single bond. C-glycosyl flavonoids showed a wide range of biological activities. This emphasizes the significance to understand the conformational stability of C-glycosyl flavonoids in drug development. Three C-glycosyl flavonoids, vaccarin (1), isovitexin-2”-O-arabinoside (2) and spinosin (3), were found to exist as rotamers in the light of their featured behavior in nuclear magnetic resonance spectroscopy (NMR). Some separated signals were observed in their ¹H-NMR and ¹³C NMR spectra. Variable-temperature (VT) ¹H-NMR experiments were then conducted to study the observation and to determine their rotational energy barriers and then evaluate their conformational stability. The temperature varied from 298K to 363K and separated signals merged at high temperature. With the help of Eyring equation, the rotational energy barriers of compounds 1-3 were calculated and found much lower than 24 kcal/mol. When the energy barrier is high enough (> 24 kcal/mol) and the time scale for interconversion (halflife > 1000 s) is long enough for isolation of individual rotamers, the isomers are termed atropisomers, which thus will display axial charity. According to this standard, the compounds 1-3 may not exhibit atropisomerism and isolation of rotamers should be difficult. Their relatively low energy barriers indicate they can be developed as rapidly equilibrating mixture.

Flow Synthesis of 2‐[Methyl(pyridin‐2‐yl)amino]ethanol: An Experimental and Computational Study

AbstractMicroreactor technology is increasingly applied in the chemical‐pharmaceutical industry for safer and more efficient drug production as compared to the traditional batch process. This technology is employed for the first time to study the production of 2‐[methyl(pyridin‐2‐yl)amino]ethanol, the first intermediate in rosiglitazone synthesis. Under the optimum operating conditions, a single microreactor chip at 160 °C allowed to produce the equivalent of more than five batch reactors at 120 °C. The kinetic study indicated that the reaction is second order. Thermodynamic parameters were determined by the Eyring equation and density functional theory (DFT) calculations with good agreement. DFT results suggested a concerted nucleophilic aromatic substitution reaction mechanism.

Synthesis of ternary nanoparticles using the complexation-reduction method and their catalytic activities for hydrogen generation from formic acid

A complex-reduction method was used for the synthesis of glycine-capped copper nanoparticles (Gly-CuNPs). Glycine-Cu2+ was prepared at room temperature, and the resulting complex was treated with NaBH4. Gly-Cu/Ag and Gly-Cu/Ag/MnO2 were prepared by using the stepwise metal displacement plating method. Gly-Cu, Gly-Cu/Ag and Gly-Cu/Ag/MnO2 were employed as catalysts for hydrogen generation from the decomposition of formic acid. The alkaline barium hydroxide solution was employed to trap CO2 formation, and pseudo-first-order rate constants were calculated by using the kobs = 2.303/t log(Aα-A0/Aα-At) relation. Hydrogen generation followed fractional order kinetics with formic acid, and various kinetic parameters were calculated for various concentrations of promoter (sodium format), catalyst and temperature. The catalytic activity was found to increase with an increasing number of incorporated metals, and the order of reactivity was as follows: Gly-Cu/Ag/MnO2 > Gly-Cu/Ag > Gly-Cu. For Gly-Cu/Ag/MnO2, the values of activation parameters (Ea = 56 kJ/mol, ∆H# = 53 kJ/mol, ∆S# = − 68 J/K/mol) were determined with the Arrhenius and Eyring equations, which show higher catalytic efficiency than that of Gly-Cu/Ag (Ea = 69 kJ/mol, ∆H# = 66 kJ/mol, ∆S# = − 25 J/K/mol) due to the synergistic effect and strong interactions between the three metals. The catalytic stability and recyclability were excellent for five consecutive cycles, but the stability and recyclability decreased due to the higher reactivity of MnO2 NPs.