Densities,Refractive Indices,Ultrasonic Speeds and Excess Properties of Acetonitrile + Poly(ethylene glycol) Binary Mixtures at Temperatures from 298.15 to 313.15 K

The densities, ρ, refractive indices, n _D, and ultrasonic speeds, u, of binary mixtures of acetonitrile (AN) with poly(ethylene glycol) 200 (PEG200), poly(ethylene glycol) 300 (PEG300) and poly(ethylene glycol) 400 (PEG400) were measured over the entire composition range at temperatures (298.15, 303.15, 308.15 and 313.15) K and at atmospheric pressure. From the experimental data, the excess molar volumes, \( V_{\text{m}}^{\text{E}} \) , deviations in refractive indices, \( \Delta n_{\text{D}} \) , excess molar isentropic compressibility, \( K_{{s , {\text{m}}}}^{\text{E}} \) , excess intermolecular free length, \( L_{\text{f}}^{\text{E}} \) , and excess acoustic impedance, Z ^E, have been evaluated. The partial molar volumes, \( \overline{V}_{\text{m,1}} \) and \( \overline{V}_{\text{m,2}} \) , partial molar isentropic compressibilities, \( \overline{K}_{{s , {\text{m,1}}}} \) and \( \overline{K}_{{s , {\text{m,2}}}} \) , and their excess values over whole composition range and at infinite dilution have also been calculated. The variations of these properties with composition and temperature are discussed in terms of intermolecular interactions in these mixtures. The results indicate the presence of specific interactions among the AN and PEG molecules, which follow the order PEG200 < PEG300 < PEG400.     

Volumetric Properties of Sodium Nitrobenzoate in <Emphasis Type="Italic">N</Emphasis>, <Emphasis Type="Italic">N</Emphasis>-Dimethylformamide–Water Mixtures at 298.15 K

Densities of sodium nitrobenzoate (o-, m-, p-) have been measured in dimethylformamide (DMF)–water mixtures at 298.15 K with an oscillating-tube densimeter. From these densities, apparent molar volumes of sodium nitrobenzoate in DMF–H₂O-mixtures have been calculated and partial molar volumes at infinite dilution have been evaluated. Substituent and solvent effects on the transfer volumes of each isomer from water to DMF–H₂O-mixed solvents have also been obtained. The results are explained in terms of solvent–solvent and solute–solvent interactions.     

Volumetric Properties for Binary Mixtures of Nonane + Decane at Temperatures from <Emphasis Type="Italic">T</Emphasis>=283.15 to 353.15 K and at <Emphasis Type="Italic">p</Emphasis>=0.7 atm

Densities of the binary mixture of nonane with decane were measured at temperatures from 283.15 to 353.15 K at atmospheric pressure (0.7 atm). Measurements have been made over the full range of compositions and for the pure compounds by using a vibrating-tube densimeter (VTD). Excess molar volumes have been obtained from these experimental results and were fitted to a Redlich–Kister type expansion. The excess molar volumes exhibit small positive and small negative deviations from ideal behavior in the temperature interval studied. Partial molar volumes and partial molar volumes at infinite dilution have been determined for each component.     

Characteristics of the hydrogen bond and the structure of Н-complexes of <Emphasis Type="Italic">p</Emphasis>-n-propyloxybenzoic acid and <Emphasis Type="Italic">p</Emphasis>-n-propyloxy-<Emphasis Type="Italic">p</Emphasis>′-cyanobiphenyl

The conformational properties of p-n-propyloxybenzoic acid and p-n-propyloxy-p′-cyanobiphenyl molecules, which can exhibit liquid crystalline properties in the formation of Н-complexes, are studied (DFT/B3LYP)/cc-pVTZ method). It is found that a molecule of p-n-propyloxybenzoic acid has 16 conformers that can be divided into four groups with respect to relative energies (0 kcal/mol, 1.6 kcal/mol, 6.5 kcal/mol, and 8.1 kcal/mol), and a molecule of p-n-propyloxy-p′-cyanobiphenyl has six conformers with relative energies of 0 kcal/mol (two conformers, φ(С_Ph–O–C–C)=180°) and 1.6 kcal/mol (four conformers, φ(С_Ph–O–C–C)=64.4°). In all conformers of the 3-AOCB molecule, phenyl rings are turned at 35° relative to each other. A conformation with the planar arrangement of two rings has a higher energy by 1.5 kcal/mol. Barriers to the internal rotation of different groups are determined and it is established that the structural nonrigidity of the molecules is mainly due to the possible rotation of the–C₂Н₅ moiety about the C–C bond. It is shown that with increasing temperature the vibrational amplitudes of the OC₃H₇ substituent, which enhance the probabilities of transitions between the conformers, become appreciably larger. It is found that p-n-propyloxybenzoic acid and p-n-propyloxy-p′-cyanobiphenyl can form Н-complexes with the medium hydrogen bond. Two types of the structural organization of Н-complexes are considered: linear and angular. The similarity of energies of Н-complexes with different structures (NBO analysis) can be the reason for the occurrence of two liquid crystalline subphases of p-n-propyloxybenzoic acid and p-n-propyloxy-p′-cyanobiphenyl system.     

Application of silica-supported Fe–Cu nanoparticles in the selective hydrogenation of <Emphasis Type="Italic">p</Emphasis>-dinitrobenzene to <Emphasis Type="Italic">p</Emphasis>-phenylenediamine

Supported bimetallic Fe–Cu/SiO₂ materials are synthesized, and their catalytic activity in hydrogenation of dinitrobenzene to phenylenediamine at 145–180°С and 1.3 MPa hydrogen pressure is studied for the first time. The best results (89% selectivity toward _p-phenylenediamine at complete conversion of _p-dinitrobenzene) are obtained for the sample synthesized via co-deposition with subsequent calcination at 300°С. The sample contains 7% iron and 3% copper. The formation of separate phases of metal oxides (for the catalysts prepared by impregnation) and mixed bimetallic oxide phases (in case of co-deposition procedure) in calcined samples is revealed via thermoprogrammed reduction with hydrogen.     

1,3-Diamino-2-Hydroxypropane-<Emphasis Type="Italic">N</Emphasis>,<Emphasis Type="Italic">N</Emphasis>,<Emphasis Type="Italic">N</Emphasis>′,<Emphasis Type="Italic">N</Emphasis>′-Tetraacetic Acid: Crystal and Molecular Structures

The synthesis, IR spectroscopic study, and X-ray diffraction analysis (CIF file CCDC no. 1574078) are carried out for 1,3-diamino-2-hydroxypropane-N,N,N′,N′-tetraacetic acid (I). The structural units of a crystal of compound I are (H_4.5HPdta)^0.5– anions, (H_5.5HPdta)^0.5+ cations, and molecules of water of crystallization joined by a branched network of hydrogen bonds: strong intermolecular O–H…O and intramolecular N–H…O bonds.     

Ultrasonic Investigations in Ternary Mixtures Containing Water, 2-Butoxyethanol and <Emphasis Type="Italic">t</Emphasis>-Butanol at 298.15 K

Ultrasonic speeds in, and isentropic compressibilities of, aqueous solutions of water + 2-butoxyethanol (2BE)+t-butanol have been determined at 298.15 K. The concentrations of t-butanol at which the ultrasonic speed becomes maximum and isentropic compressibility becomes minimum are found to decrease with increases in the concentration of 2BE, x _2BE, in the cosolvent (aqueous 2BE). This behavior indicates that the aqueous ternary solutions are less structured than aqueous t-butanol. In the presence of 2-butoxyethanol, enhancement in the hydrogen bonded structure of water due to hydrophobic hydration between t-butanol and water molecules decreases as the concentration of x _2BE in the cosolvent increases. When x _2BE>0.2, the ternary solution behaves like a normal liquid. This behavior is also very well reflected in the concentration dependence of the excess ultrasonic speed and excess isentropic compressibility. The optimum concentrations of t-butanol, ($x_{\mathrm{t}\mbox{-}\mathrm{B}}$x_{\mathrm{t}\mbox{-}\mathrm{B}})_opt, at which extrema in ultrasonic speed, isentropic compressibility, excess ultrasonic speed and excess isentropic compressibility are observed decrease with increase in x _2BE in the cosolvent. The results are explained as being due to a reduction in the strength of hydrophobic interactions responsible for enhancement in the structure of water in aqueous t-butanol in the presence 2BE. Beyond (x_t-Bx_{\mathrm{t}\mbox{-}\mathrm{B}})_opt, the hydrogen bonded network of water collapses and water, 2-butoxyethanol and t-butanol molecules interact with each other as normal liquid molecules.     

Volumetric Properties for Binary and Ternary Mixtures Containing Benzyl Alcohol,Ethyl Butyrate and Diethyl Malonate at <Emphasis Type="Italic">T</Emphasis> = (293.15–313.15) K and <Emphasis Type="Italic">p</Emphasis> = 0.087 MPa

The densities of binary and ternary mixtures of benzyl alcohol + ethyl butyrate and/or diethyl malonate were measured at T = (293.15–313.15) K and p = 0.087 MPa. From these data, the excess molar volumes, partial molar volumes, excess partial molar volumes, partial molar volumes at infinite dilution, thermal expansion coefficients and their excess values were calculated. The Redlich–Kister equations were fitted to the excess molar volumes data. The results show that the excess molar volumes for all considered binary and ternary systems are negative and decrease with increasing temperature. The same behavior was observed for the excess thermal expansion coefficients. Data for excess volumes in ternary system were fitted with the Nagata–Tamura and Cibulka models for which the Cibulka equation showed better fitting. The intermolecular interactions between molecules in these mixtures are discussed and explained based on these experimental data.     

Specific Refractive Index Increment (∂<Emphasis Type="Italic">n</Emphasis>/∂<Emphasis Type="Italic">c</Emphasis>) of Polymers at 660 nm and 690 nm

The specific refractive index increment (?n/?c) is an essential datum for the accurate quantitation of molar mass averages and distributions (inter alia) of macromolecules when refractometry, static light scattering, and/or viscometry detection are coupled on-line to size-based separation techniques. The latter include methods such as size-exclusion and hydrodynamic chromatography, and asymmetric and hollow-fiber flow field-flow fractionation. The ?n/?c is also needed for accurate determination of the weight-average molar mass of polymers by off-line, batch-mode multi-angle static light scattering. However, not only does ?n/?c differ among chemical species, it also depends on experimental conditions such as solvent, temperature, and wavelength. For the last 17 years, the author’s laboratories have measured the ?n/?c of a variety of natural and synthetic polymers, at both 690 nm and, more recently, 660 nm, under a variety of solvent and temperature conditions. In all cases, this has been done by off-line, batch-mode differential refractometry, not by assuming 100% analyte column recovery and 100% accurate peak integration. Results of these determinations are presented here, along with the relevant experimental data.     

Tri-<Emphasis Type="Italic">p</Emphasis>-Tolylbismuth Diperchlorate and μ-Oxo-bis[(perchlorato)tri-<Emphasis Type="Italic">p</Emphasis>-tolylbismuth]: Synthesis and Structure

Tri-p-tolylbismuth perchlorate (1) and μ-oxo-bis[(perchlorato)tri-p-tolylbismuth] (2) have been synthesized by the reaction between tri-p-tolylbismuth dibromide and silver perchlorate and its hydrate. The complexes have been studied by chemical analysis, IR spectroscopy, and X-ray diffraction. Complex 1 is triclinic, space group Pī, Z = 4, a =10.7271(9) Å, b = 13.5585(11) Å, c = 18.1592(13) Å, α = 110.867(3)°, β = 94.944(3)°, γ = 96.888(3)°, V = 2426.3(3) Å3, ρ_calcd = 1.865 g/cm3; complex 2 crystallizes in trigonal symmetry, space group R\(\bar 3\), a = 13.1157(2) Å, c = 22.1959(2) Å, γ = 120°, V = 3306.64(8) ų, ρ_calcd = 1.777 g/cm³. The bismuth atoms in the molecular structure of complex 1 have a distorted trigonal bipyramidal coordination to the apically arranged oxygen atoms of perchlorate ions (Bi–C, 2.180(5)–2.201(5) Å; Bi–O, 2.324(4)–2.355(4) Å; OBiO axial angles, 170.1(1)°, 174.5(1)°). The structure of complex 2 contains binuclear [p-Tol₃Bi(ClO₄)]₂O molecules (Bi–O, 2.371(15), 1.9107(7) Å; OBiO axial angle, 180.0°).     

Thermochemistry of glycyl-<Emphasis Type="Italic">DL</Emphasis>-α-alanine dissolution in water-alcohol solutions at 298.15 K

Integral enthalpies of glycyl-DL-α-alanine dissolution in aqueous solutions of ethanol, 1-propanol, and 2-propanol at concentrations of alcohols up to 0.4 mol fraction were measured by the calorimetry method. Standard values of the enthalpies of the peptide dissolution Δ_sol H ⁰ and transfer Δ_tr H ⁰ from water in mixed solvents were calculated. Dependences of the thermochemical characteristics of glycyl-DL-α-alanine dissolution on the concentration of cosolvents are of an extreme character. Within the limits of McMillan-Mayer’s theory enthalpy coefficients of pairwise interactions (h _xy ) of the studied compound with molecules of alcohols were calculated. They have positive values increasing in the series ethanol, 1-propanol, 2-propanol. The effect of the structure of dipeptides and composition of water-alcohol solvents on the dissolution enthalpy characteristics was considered on the basis of the obtained experimental and calculated data.     

Volumetric,Acoustic and Transport Properties of Metformin Hydrochloride Drug in Aqueous <Emphasis Type="SmallCaps">d</Emphasis>-Glucose Solutions at <Emphasis Type="Italic">T</Emphasis> = (298.15–318.15) K

Apparent molar volumes, apparent molar adiabatic compressibilities and viscosity B-coefficients for metformin hydrochloride in aqueous d-glucose solutions were determined from solution densities, sound velocities and viscosities measured at T = (298.15–318.15) K and at pressure p = 101 kPa as a function of the metformin hydrochloride concentrations. The standard partial molar volumes (\( \phi_{V}^{0} \)) and slopes (\( S_{V}^{*} \)) obtained from the Masson equation were interpreted in terms of solute–solvent and solute–solute interactions, respectively. Solution viscosities were analyzed using the Jones–Dole equation and the viscosity A and B coefficients discussed in terms of solute–solute and solute–solvent interactions, respectively. Adiabatic compressibility (\( \beta_{s} \)) and apparent molar adiabatic compressibility (\( \phi_{\kappa }^{{}} \)), limiting apparent molar adiabatic compressibility (\( \phi_{\kappa }^{0} \)) and experimental slopes (\( S_{\kappa }^{*} \)) were determined from sound velocity data. The standard volume of transfer (\( \Delta_{t} \phi_{V}^{0} \)), viscosity B-coefficients of transfer (\( \Delta_{t} B \)) and limiting apparent molar adiabatic compressibility of transfer (\( \Delta_{t} \phi_{\kappa }^{0} \)) of metformin hydrochloride from water to aqueous glucose solutions were derived to understand various interactions in the ternary solutions. The activation parameters of viscous flow for the studied solutions were calculated using transition state theory. Hepler’s coefficient \( (d\phi /dT)_{p} \) indicated the structure making ability of metformin hydrochloride in the ternary solutions.     

Controlled radical copolymerization of styrene and <Emphasis Type="Italic">tert</Emphasis>-butyl acrylate in the presence of tri-<Emphasis Type="Italic">n</Emphasis>-butylborane–<Emphasis Type="Italic">p</Emphasis>-quinone catalytic system

Radical copolymerization of styrene with tert-butyl acrylate is studied under different conditions. It is found that the addition of tri-n-butylborane or tri-n-butylborane along with p-quinones (2,3-dimethylbenzoquinone, 2,5-di-tert-butylbenzoquinone) results in changes in the relative activities of monomers. Copolymerization in the presence of tri-n-butylborane and p-quinones proceeds via the mechanism of reversible inhibition and is characterized by the linear increase in number-average molecular weight with conversion and by the capacity of copolymers of reinitiation. The hydrolyzed copolymer samples form more stable films compared to copolymers prepared via conventional radical copolymerization.     

SBR composites reinforced with <Emphasis Type="Italic">N</Emphasis>-isopropyl-<Emphasis Type="Italic">N</Emphasis>′-phenyl-<Emphasis Type="Italic">P</Emphasis>-phenylenediamine-modified clay

SBR compounds including the N-isopropyl-N’-phenyl-p-phenylenediamine-modified clay(organoclay) were prepared.Effects of modified clay and antioxidant(IPPD) contents on mechanical and rheological properties of SBR composites were studied.FTIR results confirmed that the clay was chemically modified by IPPD and changed into an organoclay.X-ray diffraction(XRD) results confirmed the increase in interlayer distance of the clay due to the insertion of IPPD.Rheological and cure characteristics of SBR compounds were determined using RPA(Rubber Process Analyzer) and rheometer.Scorch time and cure time of SBR compounds decreased with introduction of the organoclay.Mechanical properties and heat aging resistance of the SBR composites were improved significantly by incorporation of the organoclay.     

<Emphasis Type="Italic">N</Emphasis>′-tetrazolylmethoxyl derivatives of <Emphasis Type="Italic">N</Emphasis>-methyldiazene <Emphasis Type="Italic">N</Emphasis>-oxides

A preparation method was developed for previously unknown tetrazole derivatives containing in the 1, 2, and/or 5 positions of the tetrazole ring N-methyldiazene-N-oxide-N′-oxymethyl groups.     

Densities and Refractive Indices of Binary Mixtures of Olive Oil + Alkanols at 298.15 K

Densities and refractive indices of mixing of olive oil with the alkanols: methanol, ethanol, 1-propanol, 2-propanol and 1-butanol, have been measured as a function of the composition at T = 298.15 K. Excess molar volumes, $ V_{\text{m}}^{\text{E}} $ , and deviation in refractive index, Δn _D, were calculated and correlated by a Redlich–Kister type function, to derive the coefficients and estimate the standard error. For mixtures of olive oil with alkanols, $ V_{\text{m}}^{\text{E}} $ is positive, except with ethanol and methanol where a sigmoidal variation is observed. Δn _D is positive over the entire range of mole fraction. The effect of chain length of the alkanols on the excess molar volumes and deviation in refractive index of the mixtures with olive oil are discussed.     

Adsorption of <Emphasis Type="Italic">N</Emphasis>-hydrocinnamoyl-<Emphasis Type="Italic">N</Emphasis>-phenylhydroxylamine on pure minerals

Equilibrium adsorption studies of N-hydrocinnamoyl-N-phenylhydroxylamine (HCNPHA) on galena, sphalerite, pyrite, chalcopyrite and quartz at pH 9 and 10 are reported. All adsorption isotherms followed Langmuir model, however, Freundlich type was observed for quartz. As HCNPHA is a strong chelating agent, formation of monolayers by chemisorption appeared to be the most probable mechanism of adsorption on the base-metal sulphide minerals. Specific adsorption of HCNPHA on iron containing minerals, namely, chalcopyrite and pyrite, was about three times that on galena and sphalerite, and specific adsorption on quartz was the lowest amongst the minerals studied. Specific adsorptions (in μmol/g) of HCNPHA on the minerals at pH 9 are: sphalerite: 30.5; galena: 26.9; chalcopyrite: 112.3; pyrite: 145.4; quartz: 2.9. Compared to pH 9, specific adsorption of HCNPHA on the minerals decreased at pH 10, indicating hydroxylation of mineral sites due to higher hydroxide ion concentration at pH 10. A spectral-colorimetric procedure was developed for the quantitative estimation of HCNPHA. Due to deprotonation of hydroxamic acids direct estimation using UV absorption was not possible. Hence, complexation of HCNPHA with Fe³⁺ was used to develop a purple coloured complex that absorbs in the visible region with λ _max=500 nm. Change in concentration of HCNPHA was measured from absorbance of the HCNPHA- Fe³⁺ complex at 500 nm.     

Conformational analysis of the structure of <Emphasis Type="Italic">p</Emphasis>-butoxybenzylidene-<Emphasis Type="Italic">p</Emphasis>′-propionyloxyaniline at temperatures of crystal → nematic and nematic → isotropic liquid phase transitions

The molecular structure and conformational properties of the p-butoxybenzylidene-p′-propionyloxyphenylaniline molecule in the crystalline state and at temperatures of the crystal → nematic and nematic → isotropic liquid phase transitions were examined by AM1 calculations. It was found that the nematic → isotropic liquid phase transition is accompanied by a change in the molecular conformation.     

<Emphasis Type="Italic">N</Emphasis>-arylsulfanyl-<Emphasis Type="Italic">N</Emphasis>-arylsulfonyl(acyl)-<Emphasis Type="Italic">N</Emphasis>′-phenylthiourea sodium salts

Reactions of N-arylsulfonyl(acyl)arenesulfenamide sodium salts with phenyl isothiocyanate afforded N-arylsulfanyl-N-arylsulfonyl(acyl)-N-phenylthioura sodium salts which were found to increase thermal stability of finely dispersed poly(vinyl chloride).Translated from Zhurnal Organicheskoi Khimii, Vol. 40, No. 10, 2004, pp. 1532–1535.Original Russian Text Copyright © 2004 by Koval, Oleinik.     

Crystallization and Simulation Studies in <Emphasis Type="Italic">m</Emphasis>-Dinitrobenzene–<Emphasis Type="Italic">p</Emphasis>-Chloroaniline Eutectic System

Thaw-melt method showed that the phase diagram of m-dinitrobenzene (m-DNB)–p-chloroaniline (p-CA) system belongs to simple eutectic type. The kinetics of solidification followed Hillig and Turnbull’s equation. Excess thermodynamic functions and FT-IR spectral studies indicated some weak interaction between the component molecules in the eutectic. The mechanical strength of the eutectic was found to be higher than those of its components. Molecular stability was predicted on the basis of frontier molecular orbital analysis. The value was found to be 0.06073 a.u. for eutectic, indicating. the possibility of charge transfer interaction during the eutectic formation. Results showed that the eutectic is stabilized by hydrogen-bond formation. Calculated interaction energy of reactants and eutectic was found to be–17.4 kJ mol^–1.