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The catalytic photodegradation of diclofenac, which is a non-steroidal anti-inflammatory drug, from synthetic waste water was investigated under a 254 nm ultra-violet light using MgO nanoparticle as a photocatalyst. The kinetics of the catalytic photodegradation of DF was followed in batch system. It was found that DF degrades to form by-products which are in turn degrades further with slower rates to other by-products and /or CO2 and H2O. The reaction was found to be of consecutive type with the observed pseudo first-order rate constants for the overall catalytic photodegradation (kobs1 = 0.1191, 0.0411, 0.0127 and 0.0052 min−1 for the initial concentrations of DF = 10, 20, 50 and 100 mg L−1). 100% degradation efficiency was obtained in 60 min for 10 mg L−1 DF. The pseudo-first order rate constant for the adsorption (kAds) of DF on 0.1 g MgO-NPs was measured as 0.00762 min−1 and the photolysis rate constant (kp) (0.0069 min−1). [ABSTRACT FROM AUTHOR]

Herein, we report a facile synthesis of ethyl-2-(4-aminophenoxy)acetate 4 as a building synthon for novel dual hypoglycemic agents. This building template was synthesized by alkylation of 4-nitrophenol with ethyl bromo-acetate followed by selective reduction of the nitro group. This reduction methoddoes not require nascent hydrogen or any reaction complexity; it goes easily via consecutive reaction in NH4Cl/Fe to yield our target synthon as very pure crystals. This product was characterized by 1HNMR, 13CNMR, COSY, NOESY NMR spectroscopy, and elemental analysis. Additionally, its structure was studied and approved by X-ray single crystal structure determination. The unit cell parameters are a = 8.2104(6)Å, b = 10.3625(9)Å, c = 11.9562(9)Å, α = 101.787(7), β = 91.849(6), and γ = 102.755(7)°, indicating that 4 was crystallized in the triclinic crystal system. The cooperative non-covalent interactions are also discussed with the aid of Hirshfeld surface analysis. The H…H, H…C, and O…H interactions have a major contribution in the molecular packing of 4. Moreover, different quantum chemical parameters were computed and discussed based on DFT calculations. The experimental UV/Vis spectra showed two bands at 299 and 234 nm, which were calculated using the TD-DFT method at 286 (f = 0.068) and 226 nm (f = 0.294), respectively. These bands were assigned to HOMO→LUMO (95%) and HOMO→LUMO+2 (86%) transitions, respectively.

Described herein is an organoborane‐catalysed consecutive borylative reduction of quinolines and isoquinolines to furnish tetrahydro(iso)quinolines bearing a C(sp3)−B bond β to the nitrogen atom. The installed C−B bond is oxidatively transformed to the hydroxy group in one pot. The present double hydroboration is proposed to proceed via a stepwise ionic mechanism involving a boronium ion. The stereo‐outcome was found to be dependent on the position (C2 vs C4) of the substituents in quinolines. [ABSTRACT FROM AUTHOR]

In this study, we developed a strategy for using the Scoggins procedure in the synthesis of acetamidines as novel CO2-triggered switchable surfactants via acetimidates by effectively tuning the chemical equilibrium. The as-synthesized N'-alkyl-N,N-diethylacetamidines exhibit excellent CO2/N2 switchability and their bicarbonate salts have the ability to emulsify oil–water mixtures. [ABSTRACT FROM AUTHOR]

Abstract: The sequential substitution of aqua ligands from [Pt{2‐(phenylthiomethyl)quinoline}(H2O)2]CF3SO3, Pt(L1), [Pt{2‐(4‐tert‐butylphenylthiomethyl)quinoline}(H2O)2]CF3SO3 Pt(L2), and [Pt{2‐(4‐fluorophenylthiomethyl) quinoline}(H2O)2]CF3SO3 Pt(L3) by thiourea nucleophiles (Nu) was studied under pseudo–first‐order conditions as a function of concentration and temperature using stopped‐flow and UV‐visible spectrophotometric techniques. The observed pseudo–first‐order rate constants for the substitutions can be described by the rate law: kobs(1/2) = k2(1/2)[Nu], where the subscript denotes the consecutive substitution steps. The first aqua ligand was substituted opposite to the strong σ‐trans‐directing thioether followed by the aqua ligand opposite to the quinoline or pyridine moieties. Second‐order rate constants, k2(1st), for the substitution of the first aqua ligand by thiourea nucleophiles ranged between 9 and 22 M−1 s−1 for Pt(L1), 86 and 326 M−1 s−1 for Pt(L2), and 58 –287 M−1 s−1 for Pt(L3). The ranges of the second‐order rate constant, k2(2nd), were always lower than the k2(1st)’s and are 0.3‐9 M−1 s‐1 for Pt(L1), 2‐20 M−1 s−1 for Pt(L2), and 0.3‐5 M−1 s−1 for Pt(L3). Aqua substitution from Pt(L2) is slower for both steps than from Pt4, its pyridyl derivative from our previous study. A Job's method of continuous variation plot suggests a species with a metal‐to‐nucleophile ratio of 1:3 as the ultimate product of the chloride substitution from the Pt(II) complexes by the incoming thiourea nucleophiles. The high and negative activation entropy and low and positive activation enthalpy values support an associative mechanism of activation, characteristic of substitution reactions occurring in square‐planar complexes. [ABSTRACT FROM AUTHOR]

The actual temperature control for consecutive reaction problem is a complex optimization problem. Genetic algorithms (GA) is a metaheuristic inspired by imitating the processes observed during natural evolution. It has a strong global search ability and less computation time, but it exists the premature convergence and poor stability. Ant colony optimization (ACO) is a metaheuristic inspired by imitating the behavior of real ants. It has the robustness and parallel computation, but it exists the slow convergence speed and stagnation phenomenon. In this paper, a new genetic and ant colony self-adaptive hybrid (NGASAH) algorithm based on the chaotic searching strategy, multi-populations and self-adaptive parameter control strategies is presented. In the proposed NGASAH algorithm, the chaotic searching strategy is used to avoid the optimal solution. The strategy of the multiple populations is used to avoid to converge to a local extreme point of all particles. The strategy of self-adaptive parameter control is used to dynamically balance the local search ability and the global ability, and improve the convergence speed. The actual temperature control of consecutive reaction problem is used to test the validity of the NGASAH algorithm. The experiment results show that the NGASAH algorithm can obtain the global search ability and the faster convergence speed in solving the complex optimization problems. [ABSTRACT FROM AUTHOR]

This contribution shows, that an optimal experimental design for an accurate determination of kinetic parameters based on bootstrapping can be calculated in reasonable time. As example system, a consecutive reaction with kinetics of first order was used. Bootstrapping for estimation of parameter errors has a significantly higher computational demand than the classical method, based on the Fisher information. But bootstrapping has the big advantage of not requiring the probability densities of the parameters or measurement errors to follow any distribution. They don't even have to be known. [ABSTRACT FROM AUTHOR]

In this study, the catalytic performance of CO 2 hydrogenation reaction over Pt/TiO 2 catalyst has been evaluated. The effect of Pt particle size and reaction conditions ( e.g ., temperature and space velocity) on the selectivity of CO and CH 4 was identified. CH 4 formed over the Pt/TiO 2 catalysts following a consecutive pathway (likely, CO 2 → CO → CH 4 ) and the Pt-CO species derived from the reverse water gas shift (RWGS) reaction was supposed to be the key intermediate for the formation of CH 4 . By introducing an in situ FTIR experiment, the Pt-O v -Ti 3+ species formed at the interface between Pt and reducible TiO 2 support was identified as the active sites for the formation of CO, while large Pt particles facilitate the hydrogenation of CO to produce CH 4 at higher temperature. [ABSTRACT FROM AUTHOR]

Kinetics study of chemical reaction is important in producing optimum product, designing a reactor, analyzing a compound, and many other purposes. This work presents the result of study of consecutive pseudo first order reaction between glycine and isoleucine with o-phthaldialdehyde and 2-mercaptoethanol in borate buffer solution at pH=9.0. Continuous detection was used to follow the change of fluorescence intensity of formed isoindole during the reaction. Although concentrations of initial compound and its derivative were not known; by using iteration method, the reaction constants could be determined with high precision from single experiment data. Result of the work showed that reaction rate constants k1 and k2 for consecutive reaction of glycine with excess of o-phthaldialdehyde and 2-mercaptoethanol were 18.75x10-3 and 26.70x10-5 s-1, respectively; whereas for isoleucine were 6.06x10-3 and 12.59x10-5 s-1, respectively.

This paper reports the effects of introducing oxygen into amorphous silicon films on their anode properties in all-solid-state lithium batteries. Although poor cycling performance is a critical issue in silicon anodes, it has been effectively improved by introducing even a small amount of oxygen, that is, even in Si-rich amorphous silicon suboxide ( a -SiO x ) films. Because of the small amount of oxygen in the films, high cycling performance has been achieved without lowering the capacity and power density: an a -Si film delivers discharge capacity of 2500 mAh g −1 under high discharge current density of 10 mA cm −2 (35 C). These results demonstrate that a -SiO x is a promising candidate for high-capacity anode materials in solid-state batteries. [ABSTRACT FROM AUTHOR]

An efficient and practical copper-catalyzed consecutive synthesis of quinazolin-4(3 H )-ones and pyrido[2,3- d ]pyrimidin-4(3 H )-ones from easily available 2-halobenzamides (or 2-halonicotinamides), aldehydes, and sodium azide has been developed, which gave the corresponding target products in 50–95% yields for 29 examples. This remarkable consecutive process involved sequential copper-catalyzed S N Ar, reduction, cyclization, and oxidation. Notably, this work would provide a novel synthetic strategy for bioactive molecules containing quinazolinone class skeletons. [ABSTRACT FROM AUTHOR]

The reaction of 1-chlorovinyl p -tolyl sulfoxides with excess [chloro( p -tolylsulfinyl)methyl]lithium gave methylenecyclopropanes consisting of a chloro( p -tolylsulfinyl)methylene moiety and a ( p -tolylsulfinyl)cyclopropylidene moiety. Treating the methylenecyclopropanes with butyllithium resulted in the formation of conjugated enynes. [ABSTRACT FROM AUTHOR]

The early age compressive strength development of class C fly ash-based geopolymers under high pressure and high temperatures of curing is considered as an alternative to well cements. Uniaxial compressive strength (UCS) results show how the curing temperature affects the early compressive strength development. As the temperature rises from 87 to 125°C, a consecutive reaction seems to take place at the higher concentrations of NaOH, which decrease the compressive strength at the higher temperature. The taken scanning electron microscope (SEM) images show a change in the morphology of the samples at 125°C with the higher concentrations of NaOH. Ultrasonic cement analyzers (UCA) were employed to investigate the instantaneous strength development of the geopolymeric slurries. As the common cement models were not able to assess the compressive strength development, the custom algorithm option in the UCA software was applied. The developed empirical correlations were not able to accurately estimate the sonic strength of the slurries remarkably at 125°C. The rheological measurements of the prepared geopolymeric slurries showed a Newtonian like behavior. [ABSTRACT FROM AUTHOR]

Abstract: This paper presents electrode properties of silicon nitride (SiN0.92) as a negative electrode in a lithium battery investigated in a solid electrolyte. SiN0.92 thin films formed by using pulsed laser deposition technique show redox reactions below 0.5 V vs. Li+/Li. A 200 nm thick film delivers a high capacity of 1800 mAh g−1 at the first reduction process and retains 1300 mAh g−1 after 100 cycles. Although increasing the film thickness to 500 nm decreases the capacity to some extent, the capacities in the 1st and 100th are 1200 and 700 mAh g−1, respectively, which are quite higher than that of the current carbon negative electrode. [Copyright &y& Elsevier]

Abstract: This paper describes estimation of reaction rate constants and pure ultraviolet/visible (UV–vis) spectra of the component involved in a second order consecutive reaction between Ortho-Amino benzoeic acid (o-ABA) and Diazoniom ions (DIAZO), with one intermediate. In the described system, o-ABA was not absorbing in the visible region of interest and thus, closure rank deficiency problem did not exist. Concentration profiles were determined by solving differential equations of the corresponding kinetic model. In that sense, three types of model-based procedures were applied to estimate the rate constants of the kinetic system, according to Levenberg/Marquardt (NGL/M) algorithm. Original data-based, Score-based and concentration-based objective functions were included in these nonlinear fitting procedures. Results showed that when there is error in initial concentrations, accuracy of estimated rate constants strongly depends on the type of applied objective function in fitting procedure. Moreover, flexibility in application of different constraints and optimization of the initial concentrations estimation during the fitting procedure were investigated. Results showed a considerable decrease in ambiguity of obtained parameters by applying appropriate constraints and adjustable initial concentrations of reagents. [Copyright &y& Elsevier]

Novel 5-amino-1H-1,2,3-triazoles were synthesized by a new synthetic route that involves consecutive tandem cycloaddition between nitriles and azides [ABSTRACT FROM AUTHOR]

A model of a flow ideal mixing reactor for a consecutive two-stage exothermic first-order reaction was considered. The presence of a region of multiplicity of stationary states was established. This multiplicity region can contain regions of three and five stationary states; the region of five states always appears inside the region of three stationary states. Changes in the type of stationary state stability in each of these regions are analyzed. Numerical calculations of phase trajectories in the regions of stationary state stability and instability were performed. A mechanism of the creation of a stable limiting cycle was suggested for the case of three stationary states. [ABSTRACT FROM AUTHOR]

Abstract: The performance of a consecutive reaction of the type was studied in two reactor configurations. A layered herringbone channel, which consists of two rectangular channels and a middle layer containing machined-through herringbone structures, is compared with an unstructured rectangular channel. It was found that when the reactants are not premixed before the inlet, the layered herringbone configuration shows an improved performance compared to the rectangular channel giving a 40% increase in the maximum amount of intermediate produced. The maximum concentration of intermediate is obtained at lower residence times, which indicates that reactor volume could be decreased compared to the rectangular channel. The maximum amount of intermediate and the conversion at which this maximum occurs is dependent also on the ratio (k 2/k 1) which in this work is 0.05. Good mixing characteristics and narrow residence time distribution (RTD) are responsible for the improved behaviour in the layered herringbone channel. When the reactants are premixed before the inlet the differences are more subtle, indicating that the improved reaction behaviour in the layered herringbone channel is mainly due to good mixing and to a smaller extent to narrow RTDs. Residence time distributions were calculated numerically via CFD and particle tracking methods. The RTDs for the layered herringbone channel were found to be narrower as compared to the rectangular one. The model of axial dispersion exchanging mass with a stagnant zone was used for the modelling of the RTD. It was found that the model parameters could be calculated directly from hydrodynamic data obtained from CFD calculations, without the need of particle tracking algorithms. Concepts from turbulent theory were employed for the calculation of an effective diffusion coefficient that replaced the stirring effect of the herringbones. This procedure greatly simplifies the theoretical calculation of RTDs and reaction conversions. [Copyright &y& Elsevier]

Abstract: Rare sugars are defined as monosaccharides and their derivatives that rarely exist in nature, according to the International Society of Rare Sugars. d-Allose (3-epi d-glucose) is one of the rare sugars, for which various physiological activities have recently been found, with increasing attention to its applications to bio-industry. Until now, however, there is no convenient method of measuring these sugars in a specific manner. For detecting d-allose, three consecutive enzyme reactions were devised by fabricating of a reaction batch chamber packed with l-rhamnose isomerase (LRI), d-tagatose 3-epimerase (DTE) and a screen-printed electrode, on which d-fructose dehydrogenase (DFDH) was immobilized. To obtain a substantial sensing system, extensive experimental parameters were optimized. These included the concentration of photo-crosslinkable poly (vinyl alcohol) bearing stilbazolium groups (PVA-SbQ), reaction ratios, and temperature of the batch chamber. By adopting the three consecutive enzyme reactions, an undesirable reverse reaction was minimized. As a result, the developed sensor system exhibited a good linear response on d-allose in the range from 0.1 to 50mM (r 2 =0.998). The system has an apparent advantage over the previous chromatography approach in terms of simplicity and inexpensiveness. [Copyright &y& Elsevier]

Abstract: Kinetics for citral hydrogenation was investigated over a Ni/Al2O3 catalyst both in semibatch and in batch mode with respect to the liquid phase. In the former case the liquid phase was pumped out from the reactor continuously, while the amount of catalyst was kept constant during the hydrogenation in the latter case. The idea with liquid phase drainage was to increase the catalyst bulk density with increasing reaction time. The effect of increasing catalyst bulk density on reaction kinetics and selectivity was investigated both qualitatively and quantitatively. The main parameters were hydrogen pressure (5–21bar) and temperature (50–90°C). The product selectivity, which should theoretically be independent on the changes in catalyst bulk density, varied with varying catalyst bulk density, especially at higher reaction temperatures due to catalyst deactivation. The simplified kinetic model with lumped kinetic and deactivation parameters was applied to the experimental data being able to explain results obtained under semibatch conditions with continuous liquid phase drainage out of the reactor. [Copyright &y& Elsevier]

Abstract: A kinetic spectrophotometric method for the simultaneous determination of iodate and periodate in mixtures was proposed. The method is established on the different kinetic behaviours of the analytes which react with starch–iodide in the presence of sodium chloride in sulfuric acid medium. The kinetic data were collected from 260 to 900 nm every 10 nm, within a time range of 0–180 s at 1 s interval, and the absorbance collected at 291, 354 and 585 nm, respectively, increased linearly with the concentration between 0.1–1.2 mg L−1 for both iodate and periodate. The mechanism investigation revealed that the iodate/periodate–iodide–starch system is a consecutive reaction. Subsequently, the mathematical model for the quantitative kinetic determination based on the consecutive reactions by utilizing chemometric methods was deduced, and the simultaneous determination of synthetic mixtures of iodate and periodate was then applied. Kinetic data collected at 291, 354 and 585 nm, were processed by chemometric methods, such as classical least square (CLS), principal component regression (PCR), partial least square (PLS), back-propagation artificial neural network (BP-ANN), radial basis function–artificial neural network (RBF-ANN) and principle component–radial basis function–artificial neural network (PC-RBF-ANN). The results showed that calibration model with the data collected at 354 nm had some advantages for the prediction of the analytes as compared with the ones of other two wavelengths, and the PLS and PC-RBF-ANN gave the lower prediction errors than other chemometric methods. The proposed method was applied to the simultaneous determination of iodate and periodate in several real samples; and the standard addition method yielded satisfactory recoveries in all instances. [Copyright &y& Elsevier]

Abstract: In the reaction system of alkaline hydrolysis of phenyl benzoate in the ethanol–water media, high performance liquid chromatography-diode array detector (HPLC-DAD) is used to measure the reaction and kinetic profiles are obtained. Nonlinear least squares regression (NLLS) is used to fit the kinetic profiles and then investigate the mechanism. Genetic algorithm (GA) is adopted to optimize the parameters of the postulated mechanisms, and when the minimum standard deviation of mechanical model matches the noise level of measurement, the mechanism of the reaction system can be determined, and parameters, such as rate constants of every reaction step, are resolved simultaneously. The true mechanism of the reaction system that a parallel reaction coexists with a consecutive reaction is determined. In the ethanol–water media, phenyl benzoate hydrolyzes to benzoic acid and phenol, as well as produces a transesterification that ethanyl is substituted for phenyl, and ethyl benzoate, the product of transesterification, consecutively hydrolyzes to benzoic acid and ethanol. The method to resolve online spectroscopic–kinetic data is also studied and the results show that it is hard to obtain the kinetic parameters of all components if their kinetic concentration profiles can be combined linearly in some cases whose pure spectra of components are unknown beforehand. [Copyright &y& Elsevier]

The reaction between dichloro{l-alkyl-2-(arylazo)imidazole)palladium (II), Pd(N,N')CI2 [N,N'= 1-alkyl-2-(arylazo)imidazole ≡ R'aaiR ≡ p- R'-C6H4-N=N-C3H2N2-1-R; where R' = H (a)/Me (b)/CI (e) and R = Ethyl ≡ Et (1)/Benzyl ≡ Bz (2)] and cytosine (C) has been studied spectrophotometrically in acetonitrile-water (1:1; v/v) medium at 465 nm. The product has been isolated and characterized as [Pd(N,N')C2]CI2 . The kinetics of the nucleophilic substitution reactions has been studied under pseudo-first-order conditions at 298 K. This reaction follows two-step consecutive path (A,→B→C); each step follows first order kinetics with respect to each complex and C and follows the rate laws: Rate - I = k'obs[Pd(N,N')CI2]; k'obs= k'0 + k'2[C]0 and Rate - II = k"obs[[Pd(N,N')(C)CI]+]; k"obs= k"0 + k"2[C]0; with first-step-second-order-rate constant (k'2) greater than second-step-second-order-rate constant (k"2). The rate data supports a nucleophilic association path. External addition of CI (LiCI) suppresses the rate. Increase in π-acidity of the ligand (R'aaiR) increases the rate and follows the order: (i) (b) < (a) < (c) and (ii) (1) < (2). The reactions have been studied at different temperatures (298 - 313 K) and the activation parameters (Δ‡ H° and Δ‡S°) of each step of different reactions were calculated using the Eyring plot. [ABSTRACT FROM AUTHOR]

One-step oxidation of benzene with N2O to phenol was studied over the iron–zeolite catalysts Fe/MFI and HMFI containing an Fe impurity. Catalysts were probed at 723 K and near atmospheric pressure using a fixed bed micro-flow reactor and a molar feed ratio of benzene/N2O/He=1/3/36. A plot of the activity as a function of the loading with accessible iron, shows that mono-nuclear sites, are much more active for this reaction than dinuclear sites, which are known to catalyze NOx reduction. The benzene to phenol reaction is found to be of the consecutive type, all CO2 is formed by burning of phenol. The reaction order at these conditions is zero both in benzene and N2O. A steam pretreatment at 923 K of the low Fe-containing catalyst is found to be instrumental in the formation of the “Ex-lattice” Fe sites, required for the reaction. The same treatment when applied to high Fe-load catalysts leads also to growth of Fe oxide particles, and likely favors formation of a solid solution of Fe and Al oxide. The catalyst is deactivated by coke deposits. This can be largely suppressed by water vapor in the feed, resulting in a stable performance. It is assumed that H2O displaces C6H5OH from the sites. [Copyright &y& Elsevier]

The kinetics of the oxidative dehydrodimerisation and aromatisation of isobutene has been studied on a Bi2Sn2O7 system for a mechanistic understanding of the reaction. The rate of disappearance of isobutene has been found to be first order with respect to oxygen and second order with respect to isobutene. A good fit of the kinetic data with the Mars and van Krevelen model has been established. The kred and kox have been found to be 2.3×106 and 32×106 mol min−1 m−2 kPa−1, respectively, proving that the reduction of the catalyst is the rate-determining step. Studies were also done to verify the mechanistic pathway of the reaction. Previous workers have suggested that the reaction is essentially a consecutive reaction proceeding from isobutene to p-xylene through the intermediate dimer (2,5-dimethyl-1,5-hexadiene). Studies were done at increasing contact time to verify the mechanistic pathway of the reaction and the intermediate dimer was used as the reactant. Our results showed that the intermediate dimer is mainly oxidised to COx while p-xylene is formed through some direct parallel pathway from isobutene. [Copyright &y& Elsevier]