(Liquid + liquid) equilibria for (benzene + cyclohexane + dimethyl sulfoxide) system at T = (298.15 or 303.15) K: Experimental data and correlation

(Liquid + liquid) equilibrium (LLE) data were measured experimentally at T = (298.15 or 303.15) K and atmospheric pressure for the (benzene + cyclohexane + dimethyl sulfone (DMSO)) system. The Othmer–Tobias equation was applied to verify the reliability of the data. Based on the data, the selectivity of DMSO was estimated and compared with that of ionic liquids. The highest selectivity coefficient of DMSO can reach beyond 14, which means it is able to compete with some ionic liquids and it would be a good extractant to separate benzene from cyclohexane. At the same time, the NRTL model was used to correlate the data and the results show that the model agrees on the experimental data very well.     

Effects of clustering structure on volumetric properties of amino acids in (DMSO + water) mixtures

For a better understanding on the functions of DMSO in biological systems at a relatively lower concentration, apparent molar volumes of three typical amino acids, glycine, l-alanine and l-serine in (DMSO + water) mixtures were determined and the transfer volumes from water to the mixtures were evaluated. Together with static light scattering measurement, the results were utilised to reveal the microscopic solvent structure of (DMSO + water) mixtures and its influence on the interaction between DMSO and amino acids from a clustering point of view. The results demonstrate that the interaction between amino acids and DMSO is greatly related to the clustering structure of the mixed solvent and that amino acids interacted with already established solvent clusters. The linear dependence of transfer volume of amino acids on DMSO concentration up to 2.0 mol ⋅ dm⁻³ could be attributed to the increasing interaction with (DMSO)₁(H₂O)_n clusters. The formation of (DMSO)_m(H₂O)_n cluster via hydrophobic aggregating at higher DMSO concentration led to a decrease in hydrophobic effect of DMSO and its hydrophobic–hydrophilic and hydrophobic–hydrophobic interaction with amino acids. The structure change of solvent and the interaction between amino acid residues and DMSO was reflected by the solvation of proteins. It was found that dependence of hydrodynamic radius of bovine serum albumin and lysozyme on DMSO concentration was the same and similar to that of static light scattered by the mixed solvent, regardless of the difference in conformational change between the two proteins.     

Synthesis,characterization and antibacterial activity of some new triphenyltin(IV) sulfanylcarboxylates: Crystal structure of [(SnPh3)2(p-mpspa)], [(SnPh3)2(cpa)] and [(SnPh3)2(tspa)(DMSO)]

Five new triphenyltin(IV) sulfanylcarboxylates of the general formula [(SnPh₃)₂L] (L = pspa, tspa, fspa, p-mpspa or cpa, where p = 3-(2-phenyl)-, t = 3-(2-thienyl)-, f = 3-(2-furyl)-, p-mp = 3-(4-methoxyphenyl)-, spa = 2-sulfanylpropenoato and cpa = 2-cyclopentilyden-2-sulfanylacetate) have been synthesized by reacting triphenyltin(IV) hydroxide with the corresponding acid in ethanol/acetone. The complexes have been characterized by elemental analysis and mass spectrometry and by vibrational and NMR (¹H, ¹³C, ¹¹⁹Sn) spectroscopies. In the case of [(SnPh₃)₂(p-mpspa)] and [(SnPh₃)₂(cpa)], X-ray structural studies showed that in both compounds each Sn atom is coordinated to three phenyl C atoms and to one S or O atom of the bridge ligand L. All five complexes are active against strains of Staphylococcus aureus, but are inactive against Escherichia coli and Pseudomonas aeruginosa. From a solution of [(SnPh₃)₂(tspa)] in DMSO-d₆ the new complex [(SnPh₃)₂(tspa)(DMSO)] was isolated. The single-crystal X-ray diffractometric study of this complex is also reported, showing that both Sn atoms are bridged by the tspa ligand, whereas the molecule of DMSO is coordinated to one of the tin atoms via the oxygen atom.     

Spin transition in heptanuclear star-shaped iron(III)–antimony(V) NCS- and CN-bridged compounds

The precursor [Fe^III(L)Cl] (LH₂ = N,N′-bis(2′-hydroxy-benzyliden)-1,6-diamino-3-azahexane) has been prepared and Mössbauer spectroscopy assigned a high-spin (S = 5/2) state at room temperature. The precursor is combined with the bridging units [Sb^V(X)₆]^? (X = CN^?, NCS^?) to yield star-shaped heptanuclear clusters [(LFe^III–X)₆Sb^V]Cl₅. The star-shaped compounds are in general high-spin systems at room temperature. On cooling to 20 K some of the iron(III) centers switch to the low-spin state as indicated by Mössbauer spectroscopy, i.e. multiple electronic transitions. While the cyano-bridged complex performs a multiple spin transition the thiocyanate-compound shows no significant population at both temperatures.     

Adiabatic compressibility of pseudo-binary aqueous solutions of tert-butyl alcohol and dimethylsulfoxide as a result of ultrasonic investigations

The tert-butyl alcohol (TBA) and dimethyl sulfoxide (DMSO) are two small molecules geometrically very similar, but having different polar groups. Taking into account the intermolecular interactions in the TBA/H₂O and DMSO/H₂O systems, especially in the water-rich region of concentration, the ultrasonic speeds (high accuracy resonance method at the frequency 7.5 MHz) and densities in pseudo-binary mixtures of the system: (TBA + H₂O + DMSO) with the ratio (TBA + DMSO)/H₂O = 1/25 have been measured. From these data, various thermodynamical parameters such as adiabatic compressibility, molar volume, thermal expansivity, and the deviation from reference system have been calculated. In addition, the isobaric molar heat capacity to convert adiabatic compressibility to the isothermal one has been measured. All these parameters have been discussed to explain solute–solvent and solute–solute interactions, especially the effect of the complexation process between TBA and DMSO molecules. The composition dependence of these deviations functions was interpreted in the light of the mixing schemes in the aqueous solutions of TBA and DMSO.     

Phase equilibrium measurements of (methane + benzene) and (methane + methylbenzene) at temperatures from (188 to 348) K and pressures to 13 MPa

New isothermal pTxy data are reported for (methane + benzene) and (methane + methylbenzene (toluene)) at pressures up to 13 MPa over the temperature range (188 to 313) K using a custom-built (vapor + liquid) equilibrium (VLE) apparatus. The aim of this work was to investigate literature data inconsistencies and to extend the measurements to lower temperatures. For (methane (1) + benzene (2)), measurements were made along six isotherms from (233 to 348) K at pressures to 9.6 MPa. At temperatures below 279 K there was evidence of a solid phase, and thus only vapor phase samples were analyzed at these temperatures. For the (methane (1) + methylbenzene (3)) system, measurements were made along seven isotherms from T = (188 to 313) K at pressures up to 13 MPa. Along the 198 K isotherm, a significant change in the data’s p,x slope was observed indicating (liquid + liquid) equilibria at higher pressures. The data were compared with literature data and with calculations made using the Peng–Robinson (PR) equation of state (EOS). For both binary systems our data agree with much of the literature data that also deviate from the EOS in a similar manner. However, the data of Elbishlawi and Spencer (1951) for both binary systems, which appear to have received an equal weighting to other data in the EOS development, are inconsistent with the results of our measurements and data from other literature sources.     

Thermodynamic and acoustic properties of (heptane + dodecane) mixtures under elevated pressures

The speed of sound in (heptane + dodecane) mixtures was measured over the whole concentration range at pressures up to 101 MPa and within the temperature range from (293 to 318) K. The density of (heptane + dodecane) was measured in the whole composition range under atmospheric pressure and at temperatures from (293 to 318) K. The densities and heat capacities of these binaries at the same temperatures were calculated for pressures up to 100 MPa from the speeds of sound under elevated pressures together with the densities and heat capacities at atmospheric pressure. The effects of pressure and temperature on the excess molar volume and the excess molar heat capacity are discussed.     

Pulse radiolysis studies of the reactions of bromine atoms and dimethyl sulfoxide–bromine atom complexes with alcohols

Dimethylsulfoxide (DMSO)–Br complexes were generated by pulse radiolysis of DMSO/bromomethane mixtures and the formation mechanism and spectral characteristics of the formed complexes were investigated in detail. The rate constant for the reaction of bromine atoms with DMSO and the extinction coefficient of the complex were obtained to be 4.6×10⁹ M⁻¹ s⁻¹ and 6300 M⁻¹ cm⁻¹ at the absorption maximum of 430 nm. Rate constants for the reaction of bromine atoms with a series of alcohols were determined in CBrCl₃ solutions applying a competitive kinetic method using the DMSO–Br complex as the reference system. The obtained rate constants were ∼10⁸ M⁻¹ s⁻¹, one or two orders larger than those reported for highly polar solvents. Rate constants of DMSO–Br complexes with alcohols were determined to be ∼ 10⁷ M⁻¹ s⁻¹. A comparison of the reactivities of Br atoms and DMSO–Br complexes with those of chlorine atoms and chlorine atom complexes which are ascribed to hydrogen abstracting reactants strongly indicates that hydrogen abstraction from alcohols is not the rate determining step in the case of Br atoms and DMSO–Br complexes.     

Far-infrared investigation of kaolinite and halloysite intercalates using terahertz time-domain spectroscopy

Two clay minerals from the kaolin group, namely well-ordered kaolinite and poorly ordered halloysite, were investigated by terahertz time-domain spectroscopy (THz-TDS). Both clay samples were used for preparation of their respective intercalates using dimethyl sulfoxide (DMSO) and potassium acetate (KAc) with water. The intercalates were also characterized by X-ray powder diffraction and Fourier transform infrared spectroscopy. The dielectric behaviour of clay samples was investigated in the far-infrared region of 0.2–2.7 THz corresponding to about 6.7–89.9 cm⁻¹. The frequency dependence of the power absorption coefficient revealed clear absorption bands for DMSO intercalates but not for KAc with water. For kaolinite – DMSO intercalate a distinct doublet at 1.70 THz (56.6 cm⁻¹) and 1.88 THz (62.6 cm⁻¹), and for halloysite – DMSO intercalate a single broad band centred around 1.72 THz (57.3 cm⁻¹) were found. These bands are reported for the first time in this type of intercalation substances and indicate the application potential of THz time-domain spectroscopy for use in the investigation and detection of chemical behaviour of molecular species introduced into the interlayer space of layered substances such as clays and clay minerals. Additionally, the qualitative characteristics of observed bands of DMSO intercalates in the THz region reasonably resembled the structural order/disorder of used kaolinite and halloysite samples.     

(Vapor + liquid) equilibria for the {water + poly(ethylene glycol diacetyl ether) (PEGDAE) and methanol + PEGDAE} systems

We measured binary (vapor + liquid) equilibrium data for the {water + poly(ethylene glycol diacetyl ether) (PEGDAE) and methanol + PEGDAE} systems at pressures up to 400 kPa and temperatures from 333 K to 393 K. A static apparatus was used in this study. The measured data were correlated by the Peng–Robinson equation of state using the Wong–Sandler mixing rules with NRTL as the excess Gibbs free energy model.     

Partial molar volumes of organic solutes in water. XVII: 3-Pentanone(aq) and 2,4-pentanedione(aq) at T = (298 to 573) K and at pressures up to 30 MPa

Density data for dilute aqueous solutions of two aliphatic ketones (3-pentanone, 2,4-pentanedione) are presented together with partial molar volumes at infinite dilution calculated from the experimental data. The measurements were performed at temperatures from T = 298 K up to either T = 573 K (3-pentanone) or T = 498 K (2,4-pentanedione) and at pressure close to the saturated vapour pressure of water, at pressures between 15 MPa and 20 MPa and at p = 30 MPa. The data were obtained using a high-temperature high-pressure flow vibrating-tube densimeter.     

(Solid + liquid) equilibria of (naphthalene + isomeric dichlorobenzenes)

(Solid + liquid) equilibria (SLE) have been measured for naphthalene + o-dichlorobenzene, + m-dichlorobenzene, and + p-dichlorobenzene using differential scanning calorimetry (DSC) over the whole concentration range. It was found that the phase diagram of (naphthalene + m-dichlorobenzene) is of a simple eutectic type with the eutectic point at 244.85 K and 0.058 mole fraction of naphthalene, the phase diagram of (naphthalene + p-dichlorobenzene) is of a simple eutectic type with the eutectic point at 302.85 K and 0.390 mole fraction of naphthalene and in the system of (naphthalene + o-dichlorobenzene), a 1:1 incongruently melting compound is formed and that the phase diagram show a eutectic and a peritectic, the eutectic point is at 232.55 K and 0.130 mole fraction of naphthalene, the peritectic point at 250.15 K and 0.077 mole fraction of naphthalene. Furthermore, the activity coefficients of components in mixtures of (naphthalene + m-dichlorobenzene) and (naphthalene + p-dichlorobenzene) have been correlated by the Scatchard–Hildebrand solubility parameter expression. This approach offers a useful procedure for estimating with good accuracy.     

Isothermal phase (vapour + liquid) equilibrium data for binary mixtures of propene (R1270) with either 1,1,2,3,3,3-hexafluoro-1-propene (R1216) or 2,2,3-trifluoro-3-(trifluoromethyl)oxirane in the temperature range of (279 to 318) K

Isothermal (vapour + liquid) equilibrium data (P–x–y) are presented for the 1-propene 1,1,2,3,3,3-hexafluoro-1-propene and the 1-propene + 2,2,3-trifluoro-3-(trifluoromethyl)oxirane binary systems. Both binary systems were studied at five temperatures, ranging from (279.36 to 318.09) K, at pressures up to 2 MPa. The experimental (vapour + liquid) equilibrium data were measured using an apparatus based on the “(static + analytic)” method incorporating a single movable Rapid On-Line Sampler-Injector to sample the liquid and vapour phases at equilibrium. The expanded uncertainties are approximated on average as T = 0.07 K, 0.008 MPa, and 0.007 and 0.009 for the temperature, pressure, and the liquid and vapour mole fractions, respectively. A homogenous maximum-pressure azeotrope was observed for both binary systems at all temperatures studied. The experimental data were correlated with the Peng–Robinson equation of state using the Mathias–Copeman alpha function, paired with the Wong–Sandler mixing rule and the Non-Random Two Liquid activity coefficient model. The model provided satisfactory representation of the phase equilibrium data measured.     

Photoinduced transformation of camptothecin in the presence of iron(III) ions

To obtain the information on the photoactivated action of camptothecin (CPT) promoted by transition metals, CPT was UVA irradiated (λ = 365 nm) in dimethylsulfoxide (DMSO) solutions. Fe(III) ions present were efficiently reduced to Fe(II) under argon and also in the presence of oxygen. The photoinduced electron transfer under argon resulted into the generation of carbon-centered radicals identified by EPR spin trapping evidencing the cleavage of CPT skeleton. Whereas the absorption UV/vis experiments with equimolar ratio Fe(III):CPT excluded the formation of charge-transfer complexes, the fluorescence spectra of CPT in the presence of Fe(III) revealed a significant fluorescence quenching indicating the probability of physical association between Fe(III) and CPT species in DMSO solutions confirming Fe(III) involvement in the photoinduced transformation.     

Determination of fullerenes (C60) in artificial sediments by liquid chromatography

In this new century, nanotechnology has evolved from a novel concept to an integral aspect of product advancement. With an increasing presence of nanomaterials in commercial products, more concern about the impact of nanomaterials on human health and also the environment has been considered and evaluated. Fullerenes (C60), have been studied in several different areas and applied widely. Wider application of fullerenes into different products in the recent decades has increased the potential of fullerene releases into the environment. Fullerene research involves physical and chemical characteristics, toxicity, environment fate, and interaction with other pollutions. However, few studies have addressed fullerene quantification in solid matrices. Standardized artificial sediment was prepared following OECD guideline 225, and extracted C60 was quantified by HPLC–UV. A normal shaking method was employed for extraction for two times. Extracts were concentrated and analyzed. Recovery results revealed up to 90.7 ± 4.5%, 90.0 ± 3.8%, 93.8 ± 5.4%, respectively for 1.62, 0.65, and 0.32 μg/g C60 in dry sediment, which shows no significant difference between different concentration levels. Furthermore, extraction efficiency did not show significant difference while using Telfon^TM tubes (96.5 ± 6.0%) or silanized glass vessels (90.7 ± 4.5%). This indicated that relative low cost is required for the method to be initially started in any lab. This technique has also been applied in the determination of C60 in sediment samples collected after a 10 day benthic exposure study. Extraction precision has been increased from 4.5% (S.D.) as the validation value up to 15.4% (RSD%) or more. The increased inhomogeneity by bioturbation and matrix complexity of the sediment after the toxicity test could both lower the extraction precision.     

Conductometric study of some alkali metal halides in (dimethyl sulfoxide + acetonitrile) at T = 298.15 K

Electrolytic conductivities of some alkali metal halides, MX (M⁺ = Li⁺, Na⁺, and K⁺; X^? = Cl^?, Br^?, and I^?), NaBPh₄ and Bu₄NBr have been investigated in (20, 40, and 60) mass% {dimethyl sulfoxide (DMSO) in DMSO + acetonitrile} at T = 298.15 K. The conductance results have been analyzed by the Fuoss-conductance-concentration equation in terms of the limiting molar conductance Λ° the association constant K_A and the association diameter R. The ionic contributions to the limiting molar conductance have been estimated using Bu₄NBPh₄ as the “reference electrolyte”. The association constant K_A tends to increase in the order mass percent 20 < 40 < 60 DMSO in (DMSO + acetonitrile) which is explained by the thermodynamic parameter ΔG° and Walden product Λ°η. The results have been interpreted in terms of ion–solvent interactions and structural changes in the mixed solvents.     

Partial molar volumes of organic solutes in water. XVIII: Selected polyethers(aq) and 3,6-dioxa-1-heptanol(aq) at T = (298 to 573) K and at pressures up to 30 MPa

Density data for dilute aqueous solutions of four aliphatic ethers (2,5-dioxahexane, 3,5-dioxaheptane, 3,6-dioxaoctane, and 2,5,8-trioxanonane) and one ether-alcohol (3,6-dioxa-1-heptanol) are presented together with partial molar volumes at infinite dilution calculated from the experimental data. The measurements were performed at temperatures from T = 298 K up to either T = 443 K (3,5-dioxaheptane) or T = 573 K (other solutes) and at pressures close to the saturated vapour pressure of water, at pressures between 15 and 20 MPa and at p = 30 MPa. The data were obtained using a high-temperature high-pressure flow vibrating-tube densimeter.     

High-pressure (up to 140 MPa) density and derivative properties of some (pentyl-, hexyl-, and heptyl-) amines between (293.15 and 353.15) K

This work reports the density data (315 points) of a series of amines consisting of pentylamine, hexylamine, and heptylamine at seven temperatures between (293.15 and 353.15) K, and pressures up to 140 MPa (every 10 MPa) which allows to study the influence of the chain length. A new Anton-Paar vibrating tube densimeter, calibrated with water and vacuum with an uncertainty of ±5 · 10^?4 g · cm^?3 was used to perform these measurements. The experimental density data were fitted with the Tait-like equation with low standard deviations. In addition, the isobaric thermal expansivity and the isothermal compressibility have been derived from this equation.     

Catalytic effects of copper(II) chloride and aluminum chloride on the pyrolytic behavior of cellulose

The cellulose without and with catalyst (CuCl₂, AlCl₃) was subjected to pyrolysis at temperatures from 350 to 500 °C with different heating rate (10 °C/min, 100 °C/s) to produce bio-oil and selected chemicals with high yield. The pyrolytic oil yield was in the range of 37–84 wt% depending on the temperature, the heating rate and the amount of metal chloride. The non-catalytic fast pyrolysis at 500 °C gives the highest yield of bio-oil. The mixing cellulose with both metal chlorides results with a significant decrease of the liquid product. The non-catalytic pyrolysis of cellulose gives the highest mass yield of levoglucosan (up to 11.69 wt%). The great influence of metal chloride amount on the distribution of bio-oil components was observed. The copper(II) chloride and aluminum chloride addition to cellulose clearly promotes the formation of levoglucosenone (up to 3.61 wt%), 1,4:3,6-dianhydro-α-d-glucopyranose (up to 3.37 wt%) and unidentified dianhydrosugar (MW = 144; up to 1.64 wt%). Additionally, several other compounds have been identified but in minor quantities. Based on the results of the GC–MS, the effect of pyrolysis process conditions on the productivity of selected chemicals was discussed. These results allowed to create a general model of reactions during the catalytic pyrolysis of cellulose in the presence of copper(II) chloride and aluminum chloride.     

Proton (3 MeV) and copper (120 MeV) ion irradiation effects in low-density polyethylene (LDPE)

Low-density polyethylene (LDPE) was irradiated with proton (3 MeV) and copper (120 MeV) ions to analyze the induced modifications with respect to optical and structural properties. In the present investigation, the fluence for proton irradiation was varied up to 2×10¹⁵ protons cm⁻², while that for copper beam was kept in the range of 1×10¹ to 1×10¹³ ions cm⁻² to study the swift heavy ion-induced modifications in LDPE. Ultraviolet–visible (UV–vis), FTIR and X-ray diffraction (XRD) techniques were utilized to study the induced changes. The analysis of UV–vis absorption studies reveals that there is decrease of optical energy gap up to 43% on proton irradiation (at 2×10¹⁵ ions cm⁻²), whereas the copper beam (at 1×10¹³ ions cm⁻²) leads to a decrease of 51%. FTIR analysis indicated the presence of unsaturations due to vinyl end groups in the irradiated sample. The formation of OH and CO groups has also been observed. XRD analysis revealed that the semi-crystalline LDPE losses its crystallinity on swift ion irradiation. It was found that the proton beam (2×10¹⁵ ions cm⁻²) decreased the crystallite size by 23% whereas this decrease is of 31% in case of the copper ion-irradiated LDPE at 1×10¹³ ions cm⁻².