Enthalpies of Dilution of Aqueous Solutions of HCl, MgCl2}, CaCl2, and BaCl2 at 300, 325, and 350°C

Dilution enthalpies, measured using isothermal flow calorimetry, are reported for aqueous solutions of BaCl₂ at 300°C and 11.0 MPa, MgCl₂, CaCl₂, and BaCl₂ at 325°C and 14.8 MPa, and at 350°C and 17.6 MPa. Previously collected dilution enthalpies for aqueous solutions of MgCl₂ and CaCl₂ at 300°C and 10.3 MPa and for aqueous solutions of HCl at 250, 275, and 300°C at 10.3 MPa and 320°C at 12.8 MPa were included with the new data at 300°C and 11.0 MPa and at 350°C and 17.6 MPa when fitting the Pitzer parameters. The concentration range of the chloride solutions was 0.5 to 0.02 molal. Parameters for the Pitzer excess Gibbs ion–interaction equation were determined from the fits of the experimental heat data. Equilibrium constants, enthalpy changes, entropy changes, and heat-capacity changes for the association of alkaline earth metal ions and H⁺ with chloride ion were estimated from the heat data. For all systems, the enthalpy and entropy changes are positive and show accelerating increases with temperature. The resulting equilibrium constants show significant, but smaller, increases with temperature.     

First-principles study of structural,elastic, electronic and optical properties of rutile GeO2 and α-quartz GeO2

Structural parameters, elastic, electronic, bonding and optical properties of rutile GeO₂ and α-quartz GeO₂ have been investigated using the plane-wave ultrasoft pseudopotential technique based on the first-principles density functional theory (DFT). The ground-state properties obtained by minimizing the total energy are in favorable agreement with the previous work. Two phases of GeO₂ are found to be elastically stable and we have derived the bulk, shear and Young’s modulus, Poisson coefficient for rutile GeO₂ and α-quartz GeO₂. We estimated the Debye temperature of rutile GeO₂ and α-quartz GeO₂ from the acoustic velocity. Electronic and chemical bonding properties have been studied from the calculation of band structure, density of states and charge densities. Furthermore, in order to clarify the mechanism of optical transitions for rutile GeO₂ and α-quartz GeO₂, the complex dielectric function, refractive index, extinction coefficient, optical reflectivity, absorption coefficient, energy-loss spectrum and the complex conductivity function are calculated, which show the significant optical anisotropy in the components of polarization directions (100) and (001) for rutile GeO₂ and α-quartz GeO₂.     

Aggregation Stability of SiO2, FeOOH, ZrO2, CeO2, and Natural Diamond Sols and Their Binary Mixtures: 2. The Photometric Study of Heterocoagulation of SiO2–FeOOH, SiO2–ZrO2, SiO2–CeO2, and CeO2–Natural Diamond Binary Systems in KCl Solutions

The aggregation stability of 1 : 1 and 3 : 1 (by volume) binary mixtures of two hydrophobic (SiO₂–FeOOH), one hydrophobic and one hydrophilic (SiO₂–ZrO₂, SiO₂–CeO₂), and two hydrophilic (CeO₂–natural diamond) sols was studied by photometry over a wide range of KCl concentrations at pH 6 and 3. The stability of the mixed binary sols was determined by the stability of the sol with a predominant particle number concentration. In the SiO₂–FeOOH system, the phenomenon of heteroadagulation stabilization was caused by the electrostatic factor of the stability of adsorbed SiO₂ particles and, in the SiO₂–ZrO₂ system, by the structural factor of the stability of adsorbed hydrophilic ZrO₂ particles. The stability of binary mixtures containing one or two hydrophobic components is qualitatively explained in terms of the Derjaguin theory of heterocoagulation of hydrophobic colloids. The stability of the binary system of two hydrophilic components (CeO₂–natural diamond) is determined by the structural component of the interaction energy of particles.     

Molecular and Crystal Structure of 2, 3, 5, 6-dipropylene-r-pyrone

11NTRODUCT1ONWeattemptedtosynthesizeanextractant(1)bythereactionofadipylchloridewithcyclopentanonepiperidineenamineaccordingtoHunig'sprocedure"',however,wemainlyobtainedthetitlecompound,whichmaybepossiblyapotentialmedicinet2'3i.Itsmolecularstructurewasfinallyconfirmedbythesingle-crystalstructuredeterminationafterconventionalUV,IR,lHNMR,MSandelementana-lyticalworks.2EXPER1MENTALSECT1ON2.1SynthesisToastirredsolutioncontaining8Omlofchloroform,2.8mloftri-ethylamineand1.51g(O-Olmol)…     

Cross-coupling of 2-chlorobenzoxazole with β,γ -unsaturated grignard reagents: regioselective synthesis of 2-allyl-, 2-allenyl-, and 2-propargyl-benzoxazoles

β,γ-unsaturated Grignard reagents react regioselectively with 2-chlorobenzoxazole to give high to excellent yields of 2-allyl-, 2-allenyl-, and 2-propargyl-benzoxazoles. Reduction of 2-allylbenzoxazoles leads to quantitative yields of branched 2-alkylbenzoxazoles.     

Hydrothermal synthesis, structure and photocatalytic property of nano-TiO_2-MnO_2

TiCI4 and MnSO4.H2O as raw materials are hydrolyzed stiochiometrically, following the intermediate of oxide hydrating reacts at 150℃, 0.5 MPa in high-pressure reactor, after filtering, washing and drying, nanometric TiO2-MnO2 (Ti1-xMnxO2) is prepared. The effects of the reaction temperature and time on nanometric TiO2-MnO2 are also discussed. XRD shows that the product is TiO2-MnO2 with amorphous phase. After being sintered at above 780℃, it transfers into Ti1-xMnxO2 with a rutile structure. TEM shows that TiO2-MnO2 is the spherical particle. And the average diameter of the particles is 20 nm. The optical absorbance was determined by UV-265 spec-trophotometer after dispersing the sample in the mixture of water and glycerol with the ratio of 1 : 1 equably. It is found that the nano-material possesses the advantages of both nano-TiO2 and nano-MnO2, and it has strong absorption in the UV and visible region. Photodegradation of dyes in an aqueous solution is investigated using nanometricTiO2-MnO2 as a pho     

Synthesis and Biological Activity of β-Aminoketones,Secondary Aminopropanols and Oximes of 2-Aminothiophene Series

Russian Journal of General Chemistry - The reactions of substituted 3-dietliylaminopropan-1-ones hydrochlorides with 2-amino-6-(H, alkyl)-4,5,6,7-tetrahydrobenzo[b]thiophene-3-carbonitriles and...     

Preparation and spectroscopic properties of 2'''',5''''-dideoxynucleosidylcobalamins

Two new coenzyme B12 analogues, 2',5'-dideoxycytidylcobalamin (2a) and 2',5'-dide-oxyuridinylcobalamin (2b), and two others, 2',5'-dideoxyadenosylcobalamin (2c), and 5'-deoxy-thymidylcobalamin (2d) were prepared by an improved method. All the four analogues were investigated by UV-vis and 2D 1H NMR spectroscopy. The comparisons and discussion about their spectroscopic properties were done.     

Synthesis and Crystal Structure of 2-Amino-I, 1-diferrocenylethanol

2-Amino-l,l-diferrocenylethanol 2 was prepared by reduction of trimethylsilylcyanohydrin ether of diferrocenyl ketone. The crystal structure of 2 was further defined by X-raydiffraction.     

Vibrational spectroscopic study of the hypophosphite and phosphite anions,H2PO2−2 and HPO2−3, and of their deuteriated analogues in the solid state and in aqueous solution

A full vibrational spectroscopic study of sodium hypophosphite, sodium phosphite and their deuteriated analogues has been made. The vibrations characteristic of the hypophosphite anion have been assigned and the presence of a previously unreported band has been established for the Raman spectrum of the aqueous solution. The first Raman study of deuteriated sodium phosphite has been undertaken and a full vibrational assignment is given.     

Infrared and Raman spectra of CuCl2·2(H,D)2O and K2CuCl4·2(H,D)2O. Vibrational modes,assignment and coupling of the water librations

The i.r. and Raman spectra of CuCl₂·2H₂O and K₂CuCl₄·2H₂O and of deuterated samples of these compounds are presented in the range 50–1700 cm⁻¹ at liquid helium, liquid nitrogen, and ambient temperatures. The spectra obtained are discussed and compared with the literature data in terms of both bonding structure of the water molecules and vibrational modes, assignment, intermolecular coupling, and combination bands of the H₂O, HDO, and D₂O librations. The i.r. and Raman bands of the librational modes of CuCl₂·2H₂O are very broad even at liquid helium temperature indicating orientational disorder of the water molecules.     

Coupled cluster,MP2, and DFT study of structures,stabilities, vibrations,and bonding properties of XXeOH (X = F,Cl, Br,and I)

The optimized geometries, molecular properties, and stabilities of new noble gas molecules, XXeOH (X = F, Cl, Br, and I), were studied using CCSD, MP2, CAM-B3LYP, and WB97XD methods and large basis sets. All XXeOH molecules showed equilibrium structures with Cs symmetry. The results also showed that some bonds in XXeOH could be presented as a typical ionic bond. An alteration in ion-pair character was observed for IXeOH, showing two OH ^? and IXe ⁺ parts, while in other molecules, they could be presented as XeOH ⁺ and X ^? . Two decomposition routes were proposed for these molecules that showed high exothermic reactions. However, despite their low thermodynamic stabilities, their decomposition rate constants were small and all molecules (except BrXeOH) had high kinetic stabilities, indicating the possibility for identification and characterization of these molecules. However, in addition to the calculation of their vibrational frequencies, NBO atomic charges, and hybridizations, the bonding properties of XXeOH molecules were studied by AIM calculations (to calculate electron densities, bond elipticities, and Laplacian of electron densities) and second-order intramolecular perturbation energies using NBO calculations. Moreover, the ease of formations and relative stabilities of XXeOH molecules were compared using heats of formations, Gibbs free energies of formations and isodesmic reactions. These calculations showed that the stability of XXeOH molecules was decreased from F to I.     

Study of thermal behavior of α-PbO2, using TG and DSC

Using two techniques of thermogravimetry and differential scanning calorimetry under O₂ gas atmosphere from 25 to 600°C, the thermal behavior of laboratory-produced compound lead(IV) oxide α-PbO₂ was investigated. The identity of products at different stages were confirmed by XRD technique. Both techniques produced similar results supporting the same decomposition stages for the compound. Three distinct energy changes were observed, namely, two endothermic and one exothermic in DSC. The amount of ΔH for each peak is also reported.     

XPS primary excitation spectra of Zn 2p,Fe 2p,and Ce 3d from ZnO, α-Fe2O3, and CeO2

Metal oxides are important for current development in nanotechnology. X-ray photoelectron spectroscopy(XPS) is a widely used technique to study the oxidation states of metals, and a basic understanding of the photoexcitation process is important to obtain the full information from XPS. We have studied core level excitations of Zn 2p, Fe 2p, and Ce 3d photoelectron emissions from ZnO, α-Fe₂O₃, and CeO₂. Using an effective energy-differential XPS inelastic-scattering cross section evaluated within the semiclassical dielectric response model for XPS, we analysed the experimental spectra to determine the corresponding primary excitation spectra, ie, the initial excitation processes. We find that simple emission (Zn 2p) as well as complex multiplet photoemission spectra (Fe 2p and Ce 3d) can be quantitatively analysed with our procedure. Moreover, for α-Fe₂O₃, it is possible to use the software package CTM4XAS (Charge Transfer Multiplet program for X-ray Absorption Spectroscopy) to calculate its primary excitation spectrum within a quantum mechanical model, and it was found to be in good agreement with the spectrum determined by analysis of the experiment.     

Structures and bonding situation of Pb2X2 (X?=?H, F, Cl, Br and I)

Quantum chemical calculations using DFT (BP86) and ab initio methods (MP2, MP4 and CCSD(T)) have been carried out for the title compounds. The nature of the Pb?CPb interactions has been investigated with an energy decomposition analysis. The energy minimum structures of the halogen substituted Pb₂X₂ molecules possess a doubly bridged butterfly geometry A like the parent system Pb₂H₂. The unusual geometry can be explained with the interactions between PbX fragments in the X ²?? ground state which leads to one Pb?CPb electron-sharing ?? bond and two donor?Cacceptor bonds between the Pb?CX bonds as donor and vacant p(??) AOs of Pb. The energy difference between the equilibrium form A and the linear structure XPb??PbX (E) which is a second-order saddle point is much higher when X is a halogen atom than for X?=?H. This is because the a ⁴??^?????X ²?? excitation energies of PbX (X?=?F?CI) are higher than for PbH. The structural isomers B, D1, D2, E, F1, F2 and G of Pb₂X₂ are no minima on the potential energy surface.     

Synthesis and characterization of diblock copolymer of butadiene and 2-ethyl-2-oxazoline

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The volumes of mixing of aqueous solutions of CdCl2, CuCl2, MnCl2, and ZnCl2 with HCl at varying ionic strength at 25°C

The densities of mixtures of aqueous solutions of hydrochloric acid with solutions of cadmium chloride, copper chloride, manganese chloride, and zinc chloride have been measured at constant ionic strengths of 1.0 and 3.0 mol-kg^–1 at 25°C. The density data were used to determine the volumes of mixing (V _m ). The volume of mixing equations of Pitzer were then fit to the resulting V _m data to obtain the Pitzer parameters _V ^MN and _V ^MNX , which are the pressure derivatives of the free energy equation parameters.     

Synthesis of 2-Fluoro- Acids,Esters, and Amides From Ã-Dicyanoepoxides

The opening of Ã-dicyanoepoxides by pyridine polyhdrofluoride yields polymerisable 2-fluorocyanoformyls which may be kept intact when diluated in dichloromethane or ether. These intermediates react with nuclecophiles such as water, methanol or amines to give respectivly 2-fluoroacids, esters or amides.     

Determination of Four Active Oxygen Species Such as H2O2, •OH, •O2 −, and 1O2 by Luminol and CLA-Chemiluminescence Methods and Evaluation of Antioxidative Effects of Hydroxybenzoic Acids

Abstract

Simple and rapid chemiluminescence (CL) assays for H₂O₂, ?OH, ?O₂ ^? and ¹O₂ using 5-amino-2,3-dihydro-1,4-phthalazinedione (luminol) or 2-methyl-6-phenyl-3,7-dihydroimidazo[1,2-α]pyrazin-3-one (CLA) as CL reagents were developed. The means of the intra-assay relative standard deviations of ten replicate measurements of H₂O₂ (25-120 μM), ?OH generated from Fe(II) ion (2.5-10 μM) in the presence of 980 μM H₂O₂, ?O₂ ^? generated from hypoxanthine (HX) (7-50 μM) in the presence of 9 × 10^?3 units xanthine oxidase (XO) and ¹O₂ generated from NaOCl (3-12 mM) in the presence of 97.6 μM H₂O₂ were found to be 4.0%, 2.8%, 2.4% and 8.7%, respectively. To validate the proposed methods, the scavenging abilities of three standard antioxidative compounds, such as L-ascorbic acid, (±)-α-tocopherol and superoxide dismutase (SOD) were examined for four active oxygen species and compared with those by anelectron spin resonance (ESR) spin-trapping method. In addition, the CL methods were also applied to establish the relationships between the decrease of CL intensity and the structures as well as redox characters of syringic acid, 3-hydroxybenzoic acid, 3,4-dihydroxybenzoic acid. From the obtained results, the scavenging effects to H₂O₂, ?OH, ?O₂ ^? and ¹O₂ of other dihydroxybenzoic acids were also evaluated.     

Syntheses and Structures of Facial and Meridional Stereoisomers of κ2-N,S-Chelated Ruthenium Borate Complexes

The trans-mer-[(κ²-N,S-NS₂C₇H₄)PR₃Ru{κ³-H,S,S′-H₂B (NS₂C₇H₄)₂}], (trans-mer -1 a : R=Cy; trans-mer -1 b : R=Ph) complexes are kinetically controlled products that upon thermolysis led to the formation of cis-mer-[(κ²-N,S-NS₂C₇H₄)PR₃Ru{κ³-H,S,S′-H₂B(NS₂C₇H₄)₂}], (cis-mer- 2 a : R=Cy; cis-mer- 2 b : R=Ph) and cis-fac-[(κ²-N,S-NS₂C₇H₄)PR₃Ru{κ³-H,S,S′-H₂B(NS₂C₇H₄)₂}], (cis-fac- 3 a : R=Cy; cis-fac- 3 b : R=Ph) along with complex cis-[(κ²-N,S-NS₂C₇H₄)₂Ru(PPh₃)₂], (cis- 4 ). One of the main intentions of this study was to examine the flexibility of the borate and hemilabile N,S-chelating mercapto-benzothiazole ligands in adapting different spatial arrangements around metal center. Multinuclear spectroscopic analyses have been done to characterize all new complexes and the structures were further confirmed by single-crystal X-ray diffraction analysis. Further, Density Functional Theory (DFT) calculations were performed to provide an insight into the bonding of the complexes.