Adsorption of organic substances with different physicochemical properties

The linear regions of the adsorption isotherms of freon 13B1 (CF₃Br) on active carbons with different porous structures were studied by gas chromatography at 343–573 K. The Henry's constants were determined, and the isosteric heats of adsorption (Q) were calculated in the region of zero filling. It was established that theQ values for active carbons with different pore size distributions are almost the same and vary within 38–41 kJ mol^–1. This coincidence can be explained assuming that the interaction between the adsorbed molecules and the active carbons occurs in the pores whose sizes are comparable with those of the adsorbed molecules.For part 1, see Ref. 1.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 439–441, March, 1995.     

Preparation and some physicochemical properties of benzylammonium sulfates

New method of preparation of multisubstituted benzylammonium cations via interaction in the SO₂-L-H₂O systems (L is benzylamine, α-phenylethylamine, N,N-dimethylbenzylamine, or dibenzylamine) has been developed. The products have been studied by X-ray diffraction, IR, Raman spectroscopy, and mass spectrometry.     

Substituent effects on some physicochemical properties of chalcones and their vinylogues

Carbonyl stretching frequencies (ν_CO), dipole moments (μ), longwave maxima (λ_max), half-wave potentials (°_1/2), and relative intensities (Z/Z₀) of benzoyl-ion in mass-spectra oftrans chalcones and their vinylogues of the general type PhCO(CH=CH)_nC₆H₄R-p (I) were measured. Contrary to the previously investigated polyenes of the type R(CH=CH)_nR′ (R′ = CHO or COOEt) variation of the substituent R in compounds I has little influence on properties of I in the ground state and a satisfactory linear relationship between (ν_CO) or μ and σ constants exists only in the case of I (n = 0, 1); the best correlation with σ⁺ indicates that the mesomeric mechanism plays a great part in the transmission of electronic effects. λ_max.,E_1/2, orZ/Z₀ of all series I (n = 0–3) correlate with σ_p or σ⁰ constants, and the separation of mesomeric and inductive effects by multiparametric correlation reveals that in this case inductive effect is of great importance in the transmission of electronic effects. These features were accounted for by the non-planar structure of molecules of I, which was confirmed by X-ray analysis of I (R = Br). The Pariser-Parr-Pople method has also been applied to the calculation of π-electronic density in molecules I and it was found that the introduction of various substituents in para position of I exercises a very little influence on the electronic distribution in compounds I.     

Research of some physicochemical properties of basic aluminum sulfates

Properties of hydroxoaluminum sulfates produced by autoclave hydrolysis of aluminum containing sulfuric acid solutions in the absence and presence of ammonium sulfates.     

Synthesis and some physicochemical properties of the carbazine acid silyl esters

Structure of the dimethylcarbazine acid trimethylsilyl ether and pyrolysis of its derivative, the trimethylsilyl ester of N,N-dimethyl-N′-trimethylsilylcarbazine acid, were studied by the metods of X-ray diffraction and gas chromatography/mass spectrometry. The presence of the bifurcated hydrogen bonds between the trimethylsilyl dimethylcarbazinate molecules was detected. It was revealed why impossible to obtain dimethylaminoisocyanate even by the low-temperature pyrolysis.     

Synthesis and physicochemical properties of some spirochromenes obtained on the basis of 4-azaindoline

The condensation of N-methyl(ethyl)-3,3-dimethyl-2-methylene-4-azaindoline with salicylic acid derivatives was used to synthesize thermo- and photochromic spirochromenes. The kinetics of the spontaneous decolorization of these compounds in ethanol and toluene were studied. The photosensitivity to UV rays of the 4-azaindoline spirochromes is greater by a factor of 1.5 than that of the indoline analogs.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1367–1369, October, 1982.     

Polydispersity of pectins and some physicochemical properties of their solutions

Pectin solutions obtained in the presence of HNO₃, HCl, H₂SO₄, and H₃PO₄ have been studied by viscometry, turbidity spectra, and ultracentrifugation. Cotton pectin extracts with phosphoric acid proved to be the most unstable. The molecular masses of pectins obtained from various materials (apple, lemon, and grape press residues, beet pulp, and cotton boll valves) ranged between 14,000 and 37,000. The polydispersity of the pectins isolated was studied.Tashkent State Technical University, fax (3712) 29 48 36. Translated from Khimiya Prirodnykh Soedinenii, No. 3, pp. 349–353, May–June, 1998.     

Deriving the phylogenetic information from some physicochemical properties of protein sequences computed

The evolutionary relationships of organisms are traditionally delineated by the alignment‐based methods using some DNA or protein sequences. In the post‐genome era, the phylogenetics of life could be inferred from many sources such as genomic features, not just from comparison of one or several genes. To investigate the possibility that the physicochemical properties of protein sequences might reflect the phylogenetic ones, an alignment‐free method using a support vector machine (SVM) classifier is implemented to establish the phylogenetic relationships between some protein sequences. There are two types of datasets, namely, the “Enzymatic” (assigned by an EC accession) and “Proteins” used to train the SVM classifiers. By computing the F‐score for feature selection, we find that the classification accuracies of trained SVM classifiers could be significantly enhanced to 84% and 80%, respectively, for the enzymatic and “proteins” datasets classified if the protein sequences are represented with some top 255 features selected. These show that some physicochemical features of amino acid sequences selected are sufficient for inferring the phylogenetic properties of the protein sequences. Moreover, we find that the selected physicochemical features appear to correlate with the physiological characteristic of the taxonomic classes classified. © 2010 Wiley Periodicals, Inc. J Comput Chem, 2010     

On the interrelation between microstructure and physicochemical properties of some polyconjugate systems

Soluble oligoarylenes based on naphthalene and anthracene, and fractions of different molecular weights have been studied by electron microscopy. For the examined samples, a definite interrelation is ascertained between microstructure and physicochemical properties, such as density, x-ray parameters, heat of solution, electron paramagnetic resonance (EPR) spectra, and dark conductivity. The molecular-weight distribution of oligoarylenes is shown to decisively influence the degree of packing of macromolecules and their physicochemical properties. This allows interpretation of some anomalous properties of oligoarylenes in comparison with the first members of the corresponding homologous series.     

Electrical transport properties of some liquid metals

In the present article, we report the electrical transport properties viz. the electrical resistivity (ρ), the thermoelectric power and thermal conductivity (σ) of several monovalent, divalent and polyvalent liquid metals of the different groups of the periodic table on the basis of model potential formalism. The well-known empty core model potential of Ashcroft is used for the first time with seven local field correction functions proposed by Hartree, Hubbard–Sham, Vashishta–Singwi, Taylor, Ichimaru–Utsumi, Farid et al. and Sarkar et al. in the present computation and found suitable for such study. In the calculation of these properties we have used the values of the theoretical structure factors due to hard core fluid theory. It is concluded that the comparisons of present and theoretical or experimental findings wherever exists are highly encouraging.     

Structural properties of some liquid transition metals

This article addresses the computation of structural properties of liquid transition metals, namely, 3d (Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu and Zn), 4d (Zr, Pd, Ag and Cd) and 5d (Pt, Au and Hg). We have calculated the structure factor S(q), pair distribution function g(r), interatomic distance r ₁, coordination number n ₁, long wavelength limit of structure factor S(0) and isothermal compressibility χ_T for liquid transition metals. To describe electron–ion interaction, we have used our own model potential along with one component plasma reference system. To see the influence of exchange and correlation effect, Sarkar et al.'s [Mod. Phys. Lett. B12, 639 (1998)] local field correlation function is used. Thus, our newly constructed model potential has successfully generated the structural properties (structure factor S(q), pair distribution function g(r), interatomic distance r ₁, coordination number n ₁, long wavelength limit of structure factor S(0) and isothermal compressibility χ_T ) for liquid transition metals.     

Molecular architecture and physicochemical properties of some vinyl alcohol-vinyl acetate copolymers

Two series of vinyl alcohol-vinyl acetate copolymers were prepared by homogeneous and heterogeneous acetylation of the same precursor poly(vinyl alcohol). Their intramolecular monomer distributions were analyzed by IR spectrometry, calorimetry, and differential thermal analysis. The results show a more blocky distribution for the heterogeneously prepared copolymers. The properties of these (co)polymers in dilute aqueous solution were determined by means of viscometry. Whereas the copolymer-solvent interaction parameter of the homogeneously acetylated, random copolymers hardly varied with acetate content, a definite minimum was found for the blocky copolymers at about 7 mole% vinyl acetate. These findings were attributed to the incompatibility of dissimilar sequences, which sharply decreases with decreasing vinyl acetate sequence length. Up to about 17 mole% vinyl acetate content, the solvent quality for the copolymers is at least as good as for poly(vinyl alcohol). In addition, the dilute solution properties of the samples were established in water saturated with 1-butanol. For copolymers with up to about 17 mole% vinyl acetate, at 25°C this mixture is a better solvent than water. The highest increase in solvent quality was found for the homopolymer, whereas the increase diminished with acetate content, irrespective of the intramolecular vinyl acetate distribution. These findings are explained in terms of preferential adsorption of 1-butanol onto the (co)polymer backbone due to hydrophobic interactions and prevention of this process by the bulky acetate groups.     

Effect of electrolytes on the critical temperature of separation and physicochemical properties of binary liquid systems

The effect ions have on the equilibrium and kinetic properties of solutions near the critical temperature of separation is studied. From an analysis of the experimental data obtained in the work and from the literature it is shown that adding ions to a solution increases the correlation length of the system and changes the magnitude of the fluctuation part of the thermodynamic potential and the forces of interaction among the order parameter fluctuations in the vicinity of the critical point. This changes the parameters of the extended equation of state, increases the viscosity of substances, and lowers the coefficient of volume expansion of the system.     

Synthesis and some physicochemical properties of antamanide, retroantamanide, and perhydroantamanide

Summary The synthesis of antamanide, retroantamanide, and perhydroantamanide has been effected. It has been shown that the inversion of the direction of acylation — the equilibrium interchange of the valine and alanine residues (retroantamanide) — lowers the stability of the complexes with sodium and potassium in ethanolic solutions, while the replacement of the phenyl groups by cyclohexyl groups has practically no effect on complex formation.M. M. Shemyakin Institute of the Chemistry of Natural Compounds, Academy of Sciences of the USSR. Translated from Khimiya Prirodnykh Soedinenii, No. 4, pp. 469–474, July–August, 1971.     

The physicochemical properties of some imidazolium-based ionic liquids and their binary mixtures

The density, viscosity and conductivity of ionic liquids (ILs), 1-octyl-3-methylimidazolium tetrafluoroborate ([omim][BF4]), 1-octyl-3-methylimidazolium chloride ([omim][Cl]), 1-hexyl-3-methylimidazolium tetrafluoroborate ([hmim] BF4]), 1-hexyl- 3-methylimidazolium chloride ([hmim][Cl]), 1-hexyl-3-methylimidazolium hexafluorophosphate ([hmim][PF6]), and the [omim][BF4] + [omim][Cl], [hmim][BF4] + [hmim][Cl], and [hmim][PF6] + [hmim][Cl] binary mixtures were studied at dif- ferent temperatures. It was demonstrated that the densities of both the neat ILs and their mixtures varied linearly with temper- ature. The density sensitivity of a binary mixture is between those of the two components. The excess molar volumes (VE) of [hmim][BF4] + [hmim][Cl] and [hmim][PF6] + [hmim][Cl] mixtures are positive in the whole composition range. For [omim][BF4] + [omim][Cl], the VE is also positive in the [omim][Cl]-rich region, but is negative in the [omim][BF4]-rich re- gion. The viscosity or conductivity of a mixture is in the intermediate of those of the two neat ILs. For all the neat ILs and the binary mixtures studied, the order of conductivity is opposite to that of the viscosity. The Vogel-Tammann-Fulcher (VTF) equations can be used to fit the viscosity and conductivity of all the neat ILs and the binary mixtures. The neat ILs and their mixtures obey the Fractional Walden Rule very well, and the values of the Walden slopes are all smaller than unit, indicating obvious ion associations in the neat ILs and the binary mixtures.     

Influence of molecular weight on some properties of liquid crystalline polyurethanes

This investigation extends our previous investigations of liquid crystalline polyurethanes prepared from 4,4′-bis(2-hydroxyethoxy)biphenyl (BHBP), 2,4-tolylene diisocyanate, and poly(oxytetramethylene)diols as the flexible spacers. The influence of molecular weight of investigated polyurethanes on their properties is discussed for two series with the same content of BHBP and different lengths of flexible spacers. The polyurethanes were investigated by means of DSC, polarizing microscopy, x-ray diffractometry, and IR spectroscopy. The molecular weight distribution was determined by GPC. Morphology was studied by the SALS method. The molecular weight of polyurethanes and the length of flexible spacer influence the phase transition temperature and the range of mesophase occurrence. © 1993 John Wiley & Sons, Inc.     

The confinement and anion type effect on the physicochemical properties of ionic liquid/halloysite nanoclay ionogels

This work is the first attempt to study the physicochemical properties of ionogels - quasi-solid hybrid materials formed by ionic liquids (ILs) − 1-butyl-3-methylimidazolium (BMIm⁺) salts with dicyanamide- (DCA⁻), bis(trifluoromethylsulfonyl)imide- (TFSI⁻), and trifluoromethanesulfonate- (Otf⁻) anions - and halloysite, a powdered clay filler with nanotube particles (at the IL:Hal molar ratio of 2:1) in order to find possible new applications of ionic liquids and industrial minerals. The electron microscopy, TG, and DSC analysis, FTIR spectroscopy, X-ray diffraction analysis, conductometry and cyclic voltammetry methods are used to investigate the anion effect on the IL interaction with halloysite. It has, for the first time, been found that the distinguishing feature of halloysite interaction with an IL determining the structural changes in the clay mineral and electrochemical characteristics of the ionogels is partial dehydration of the clay and absorption of the released water by the ionic liquid. It is shown that the halloysite dehydration effect depends on the IL hydrophilicity determined by the anion type, corresponds to the series: BMImDCA > BMImOtf > BMImTFSI. The electrochemical and thermal behaviour of ILs confined within a halloysite matrix differs from that of bulk ILs and is controlled by the anion type. Temperature dependences of the structural resistance of the halloysite filler are radically different for the ILs with high and low hydrophilicity. The effects resulting from the formation of halloysite-based ionogels can be of interest to those who develop quasi-solid ionic conductors that can work within a wide temperature range.