Bubble points of hydrogen chloride–water–isopropanol and hydrogen chloride–water–isopropanol–benzene systems and liquid–liquid equilibria of hydrogen chloride–water–benzene and hydrogen chloride–water–isopropanol–benzene systems

Bubble points of the HCl–water–isopropanol and the HCl–water–isopropanol–benzene systems and liquid–liquid equilibria (LLE) of the HCl–water–benzene and the HCl–water– isopropanol–benzene systems were measured at 25–85°C and 30–70°C, respectively. The electrolyte nonrandom two-liquid model proposed by Chen et al. [C.-C. Chen, H.I. Britt, J.F. Boston, L.B. Evans, AIChE J. 28 (1982) 588–596] can satisfactorily correlate bubble points and liquid–liquid equilibria of the present mixed-solvent electrolyte systems over the entire range of temperature and concentrations using only binary adjustable parameters.     

Vapor–liquid equilibria predictions of hydrogen–hydrocarbon mixtures with the Huron–Vidal mixing rule

An excess Gibbs-equation of state (G^E-EoS) framework based on the Huron–Vidal mixing rule, has been applied to study vapor–liquid equilibria (VLE) of hydrogen–hydrocarbon mixtures. The mixing rule couples the Peng–Robinson–Stryjek–Vera (PRSV) EoS with a local composition solution model. The solution model is based on one-fluid theory treatment and assigns a single energy parameter to each binary pair. This energy parameter relates to the preference of the molecules for like to unlike interactions. The allocation of a system's number of interactions to the individual species in a binary mixture, incorporates the use of size parameters which gain significance only in the liquid phase. In a two parameter form, the framework has been used for the simultaneous data reduction of a large number of binary and several ternary hydrogen–hydrocarbon mixtures. These systems were taken over an extended range of pressures and temperatures. Results from the data reduction are reported in both tabular and graphical forms. Correlations for the model parameters have been identified with the acentric factor of the hydrocarbon in hydrogen–hydrocarbon binary mixtures. In a fully predictive mode, the model has shown to describe well VLE of binary hydrogen–linear alkane systems. Comparisons of these results with calculations from the Peng–Robinson (PR) EoS and the classical mixing rule (vdW) are included.     

Enantioselective water-soluble iron–porphyrin-catalyzed epoxidation with aqueous hydrogen peroxide and hydroxylation with iodobenzene diacetate

The asymmetric epoxidation of styrene derivatives by H₂O₂ (or UHP) to give optically active epoxides (ee up to 81%) and hydroxylation of alkanes to give optically active secondary alcohols (ee up to 78%) were carried out in methanol and water using chiral water-soluble iron porphyrins as catalysts.     

Development of hydrogen–air fuel cells with membranes based on sulfonated polyheteroarylenes

Proton-conducting membranes based on sulfonated polynaphthoyleneimide (PNI) and polytriazole (PTA) are synthesized that can be used in portable hydrogen–air fuel cells (HAFC). Membrane–electrode assemblies (MEAs) based on sulfonated PNI and PTA membranes in individual HAFC manifested power and voltammetric characteristics exceeding the characteristics of MEA based on the commercial Nafion-212 membrane. Thus, the current density of 320 mA cm^–2 and the power density of 160 mW cm^–2 are obtained at the room temperature with no pressure or gas humidification at the voltage of 0.5 V. Also activity of the oxygen electroreduction Pt–Fe/C (30 wt % of metals in total) catalyst synthesized on the basis of coordination compounds is tested in MEA HAFC. It is shown that the values of power for MEAs with the cathodic Pt–Fe/C catalyst at the voltage of 0.5 V, at the room temperature, without additional pressure and gas humidification considerably exceed the corresponding values for MEAs with the commercial E-TEK 20% Pt/C catalyst.     

Heterogeneous oxidation of alcohols with hydrogen peroxide catalyzed by polyoxometalate metal–organic framework

HSiW-MOF, PMo-MOF, HPMo-MOF and PW-MOF were synthesized and characterized by elemental analysis, UV–Vis, FT-IR, cyclic voltammetry and XRD. These compounds were used as catalyst for the selective oxidation of alcohols by hydrogen peroxide. Within them, PW-MOF showed a higher catalytic activity compared to other catalysts in a similar reaction condition. Therefore, PW-MOF catalyst system was successfully used for the selective oxidation of the benzylic, linear and secondary alcohols to the corresponding aldehydes and ketones. Also, allylic alcohols were converted to the corresponding aldehydes with high conversion and significant selectivity. Moreover, PW-MOF was stable to leaching, behaved as true heterogeneous catalysts, easily recovered by filtration, and reused four times with the preserve of the catalytic performance.     

Complexes of TETROL with selected heterocyclics: unconventional host–guest hydrogen bonding and the correlation with host selectivity

Here we investigate and compare the more salient characteristics of host–guest complexes of (+)-(2R,3R)-1,1-4,4-tetraphenylbutane-1,2,3,4-tetraol (TETROL) with four heterocyclic guests, morpholine, piperidine, pyridine and dioxane. These guests each formed inclusion compounds with TETROL, and host:guest ratios were either 1:2 or 1:1. Single crystal diffraction experiments revealed unprecedented host behaviour in the presence of both piperidine and dioxane with respect to the mode of host–guest hydrogen bonding employed. Furthermore, by utilizing ¹H-NMR spectroscopy or gas chromatography (as applicable) as methods for analysing complexes obtained from competition experiments, we were able to identify the host selectivity order, and were gratified to discover that this order correlated precisely with host–guest hydrogen bond distance.     

Hydrogen sorption–desorption studies on ZrCo–hydrogen system

The ZrCo–H₂ system was investigated in this study owing to its importance as a suitable candidate material for storage, supply, and recovery of hydrogen isotopes. Desorption hydrogen pressure-composition isotherms were generated at six different temperatures in the range of 524–624 K. A van’t Hoff plot was constructed using the plateau pressure data of each pressure-composition isotherms and the thermodynamic parameters were calculated for the hydrogen desorption reaction of ZrCo hydride. The enthalpy and entropy change for the desorption of hydrogen were found to be 83.7 ± 3.9 kJ mol^?1 H₂ and 122 ± 4 J mol^?1 H₂ K^?1, respectively. Hydrogen absorption kinetics of ZrCo–H₂ system was studied at four different temperatures in the range of 544–603 K and the activation energy for the absorption of hydrogen by ZrCo was found to be 120 ± 5 kJ mol^?1 H₂ by fitting kinetic data into suitable kinetic model equation.     

Selective oxidation of sulfides to sulfoxides with cyanuric chloride and urea–hydrogen peroxide adduct

Although a number of methods have been developed for the selective oxidation of sulfides to sulfoxides, the need remains for alternative efficient, reliable strategies that can be generally applied to various sulfides and that use readily available reagents under mild reaction conditions. Herein, we report the use of urea–hydrogen peroxide adduct (UHP) and cyanuric chloride in CH₃CN at room temperature to convert sulfides to sulfoxides in excellent yields. In particular, this protocol produced sulfoxides with aromatic rings bearing electron-withdrawing groups in excellent yields.     

A new insight on hydrogen bond donor property of bridged B–H–B protons in the interaction of diborane with some hydrogen bond acceptor molecules

Structural Chemistry - Ab initio calculations at the MP2/6-311++G(d,p) computational level were used to analyze the interactions between a molecule of B2H6 with some small molecules which often...     

Visible light-induced conversion of biomass-derived chemicals integrated with hydrogen evolution over 2D Ni2P–graphene–TiO2

Research on Chemical Intermediates - Highly selective photocatalytic conversion of biomass-derived chemicals into value-added chemicals and clean hydrogen energy under mild conditions by...     

Activity of copper–cerium–zirconium catalysts in oxidation of hydrogen

We have studied the catalytic properties in oxidation of hydrogen for copper–cerium oxide systems deposited on supports obtained by calcination of yttrium-stabilized zirconium dioxide at 300–1000 °C. We have shown that the catalytic activity of the samples obtained depends on the specific surface area of the original supports and the amount of reduced copper within the composition of the catalyst. In samples whose support has high specific surface area, the content of reduced metallic copper is greater and the catalytic activity is higher.     

Porous carbon coupled with an interlaced MoP–MoS2 heterojunction hybrid for efficient hydrogen evolution reaction

The design and development of electrocatalysts composed of non-noble-metal catalysts with both large surface area and high electrical conductivities are crucial for the hydrogen evolution reaction(HER).Here,a xylose-based porous carbon is coupled with a MoS2-Mo P heterojunction(MoS2-Mo P/FPC)hybrid and used as a promising catalyst for HER.The hybrid is prepared by immobilizing petal-like MoS2 nanosheets on porous carbon(MoS2/FPC),followed by controlling the phosphidation in Ar/H2 to form MoS2-Mo P/FPC.Red phosphorus provides the P species that can induce the construction of the heterojunction under the reducing atmosphere,along with the generation of a Mo P phase and the splitting of the MoS2 phase.The as-prepared MoS2-Mo P/FPC catalyst offers a low overpotential of 144 mV at a current density of 10 m A cm^-2 and a small Tafel slope of 41 m V dec^-1 for the HER in acidic media,as well as remarkable stability.Apart from the active nature of the hybrid,its outstanding activity is attributed to the MoS2-Mo P heterojunction,and the good charge/mass-transfer ability of porous carbon.This strategy provides a new method to develop and design low-cost and high-performance catalysts for the HER.     

Hemoglobin co-immobilized with silver–silver oxide nanoparticles on a bare silver electrode for hydrogen peroxide electroanalysis

Hemoglobin (Hb) and silver–silver oxide (Ag–Ag₂O) nanoparticles were co-immobilized on a bare silver electrode surface by cyclic voltammetry, and were characterized by UV–vis reflection spectroscopy, scanning electron microscopy, and electrochemical impedance spectroscopy. The immobilized Hb was shown to maintain its biological activity well. Direct electron transfer between Hb and the resulting electrode was achieved without the aid of any electron mediator. The reduction currents to hydrogen peroxide (H₂O₂) at co-immobilized electrodes showed a linear relationship with H₂O₂ concentration over a concentration range from 6.0?×?10^?6 to 5.0?×?10^?2 mol L^?1, and a detection limit of 2.0?×?10^?6 mol L^?1 (S/N?=?3).     

Synthesis of ɛ-caprolactone with stable hydrogen peroxide adducts

Oxidation of cyclohexanone to ?-caprolactone with stable industrially manufactured hydrogen peroxide derivatives: adduct with urea (urea hydrogen peroxide), sodium perborate, sodium percarbonate (Persol), magnesium monoperphthalate (Dismozon) was studied. Oxidation with urea hydrogen peroxide is the most efficient in hexafluoroisopropanol in the case of preliminary removal of urea in the form of an oxalate. Oxidation with sodium perborate and percarbonate provides high yields in trifluoroacetic acid. The lowest cost process consists in interaction with sodium monoperphthalate (Persol and phthalic anhydride) in an aqueous medium.     

Electrooxidation of hydrogen at Pt/carbon nanotube catalysts for hydrogen–air fuel cell

A possibility for application of the method of thin-layer rotating disk electrode (RDE) for investigation of kinetics of hydrogen electrooxidation on highly dispersed platinum catalysts formed on the carbon nanotubes (CNT) is studied. It is shown that the polarization curves of hydrogen oxidation on the studied catalysts approach the calculated curves for the diffusion overpotential of hydrogen reaction both in the acidic and alkaline electrolytes. This is the evidence, on the one hand, for a high activity of proposed catalysts in the hydrogen oxidation reaction and, on the other hand, for incorrect use of the Koutecky–Levich equation for calculating the kinetic currents in the case under consideration. The characteristics of hydrogen–oxygen fuel cell (FC) with anode based of synthesized 40Pt/CNT catalysts are highly comparative with the characteristics of FC containing commercial 60Pt catalyst (HiSPEC 9100) on the anode.     

A novel hydrogen peroxide-initiated reaction of difluorodiiodomethane with alkynes

The reaction of difluorodiiodomethane with alkynes (4a-e) in the presence of hydrogen peroxide afforded the corresponding β-iodo-α,β-unsaturated carboxylic acids.When propargylic alcohol was used as the substrate,β-iodo-α,β-unsaturated γ-butyrolactone (5f) was produced.The mechanism of the reaction was suggested.     

Green and efficient oxidation of benzylic alcohols with hydrogen peroxide catalyzed by an inorganic–organic hybrid catalyst

Inorganic–organic hybrid catalysts 1-POM(M) were prepared by electrostatic interaction between transition metal-substituted polyoxometalates, {[PW₁₁MO₃₉]^4? [M?=?Cr(III), Fe(III)], [PW₁₁MO₃₉]^5?, [M?=?Mn(II), Co(II), Ni(II), Cu(II), Zn(II)], [PW₁₁VO₄₀]^4?}, and branched organic polyammonium, (tris[2-(dimethylammonium)ethyl]-1,3,5-benzenetricarboxylate), and characterized by elemental analyses, UV–vis and FT IR spectroscopic techniques, XRD, SEM, and Thermogravimetric-Differential thermogravimetric analyses. The hybrid material 1-POM(Zn) was an efficient and selective heterogeneous catalyst in the oxidation of benzylic alcohols to their corresponding carbonyl compounds with hydrogen peroxide. The catalyst was reused several times without significant loss of catalytic activity.     

Resolution of β-unsaturated amines with isopropylidene glycerol hydrogen phthalate

1-Phenyl-2-propenylamine 2, 1-phenyl-2-propinylamine 3, 1-(1-cyclohexenyl)ethylamine 4, (E)-2-ethylidenecyclohexylamine 5 and α-methylallylamine hydrochloride 6 were selected as candidates for resolution with isopropylidene glycerol hydrogen phthalate 1, previously described as an efficient resolving agent of 1-arylalkylamines. With only the exception of 5, all these substrates were resolved by (S)-1. In particular both the enantiomers of 2 and 3 were obtained in excellent yields and with very high enantiomeric excesses. The absolute configurations of non-racemic forms of 2, 3 and 4, not prepared before except those of 3, were established by correlation with the respective hydrogenation products. The enantiomeric excesses of all the resolved substrates were accurately determined by chiral HPLC analysis. The fact that 1 resolves 4 and 6 but not their saturated analogues and shows higher efficiency in resolving 2 and 3 than 1-phenylpropylamine indicates the positive influence of the presence of β-unsaturation on the resolvability of aminic substrates with such an acid.     

Generation of hydrogen by hydroreactive compositions with γ-irradiated aluminum

The kinetics of hydrogen generation by heterogeneous hydroreactive compositions with aluminum, which was preliminarily γ-irradiated in air, held in aqueous solutions at room temperature, and annealed at a high temperature, was studied. Changes in the hydrogen generation kinetics depending on the γ-radiation dose, the composition of aqueous solution, and the temperature are caused by the conversion of aluminum oxide coatings, which should be taken into account in the prediction of the corrosion resistance of structural materials under the conditions of exposures at nuclear power plants.