Solutions Of Polar Molecules Research Articles

Far Infrared Spectra of Strongly Polar Molecules in Solid Solution. II. Hydrogen Cyanide

AbstractFar infrared matrix isolation spectroscopy of hydrogen cyanide establishes the presence of monomers, linear dimers, and linear multimers in solid Ar. Information is obtained concerning the motion of monomer molecules relative to the cage as well as the intermolecular vibrational behaviour of the dimer. – The comparison with similar studies in the mid IR reveals the high potential of the application of far IR spectroscopy of matrix‐isolated samples to the investigation of association phenomena and intermolecular interactions.

Far infrared spectra of strongly polar molecules in solid solution. I. Acetonitrile

Strongly polar molecules such as acetone, nitromethane, and acetonitrile imbedded in an inert gas matrix give rise to characteristic absorption patterns below 150 cm−1. The bands observed in the case of acetonitrile are due to an activated phonon band, to two vibrations of a monomer molecule within the polarized cage of inert gas atoms, and to two intermolecular vibrations of an antiparallel dimer.

Local order and vibrational coupling in solutions of polar molecules

The separation between the isotropic and the anisotropic component of some Raman bands of polar molecules is studied as a function of concentration in different solvents. It is found that it depends linearly on the ratio between the volume fraction and the static dielectric constant of the solution, and becomes zero at a finite concentration. It is suggested that this concentration threshold is related to the relaxation time of the vibrational energy. An explanation is proposed for the observed dependence on the dielectric constant.

Infinite dilution volatilities of polar solutes in hydrocarbons

AbstractInfinite dilution volatility data have been correlated for alcohols, esters, aldehydes, ketones, and sulfur containing hydrocarbon solutes in aliphatic hydrocarbon solvents over a wide temperature range using a temperature dependent energy parameter for the pure solute.When a polar solute molecule is surrounded entirely by nonpolar molecules, polar molecular interactions such as hydrogen bonding do not play an important role. Therefore, a single, pure solute parameter is sufficient for correlation.Calculated heats of solution at infinite dilution agree well with published calorimetric data.

Gas chromatography in qualitative analysis : XV. Deactivation of diatomaceous supports by amine antioxidants

Errors in qualitative gas chromatographic analysis due to the oxidation of apolar stationay phases and the adsorption of polar solutes are reduced by pre- treatment of diatomaaceous supports with amine antioxidants. Addition of small quantities of N,N′-disubstituted p-phenylenediamines to column packings is shown to prevent peak tailing, due to the adsorption of polar solute molecules at the liquid—solid interface, and solute decomposition. The protective film is shown to have a slightly superior thermal stability to that provided by diglycerol but to have a greater influence upon retention data.

Novel approach for dipole moment laboratory experiments. A physical chemistry laboratory experiment

The determination of the dipole moment of polar molecules in solution is a standard physical chemistry laboratory; this procedure involves a method of direct counting that has several advantages over more traditional approaches.

Dielectric Absorption of Microwave in Dilute Solutions of Polar Molecules in Non-polar Solvents

Dielectric Absorption of Microwave in Dilute Solutions of Polar Molecules in Non-polar Solvents

Spectroscopic investigation of intermolecular interactions of weakly polar molecules in liquid solution

Spectroscopic investigation of intermolecular interactions of weakly polar molecules in liquid solution

Dielectric relaxation of rigid solute molecules in benzene + paraffin solutions

The dielectric relaxation of six rigid polar solute molecules over a 40°C temperature range (20–60°C) has been studied as a function of the solvent composition (benzene + liquid paraffin mixtures).The thermodynamics of the relaxation processes are examined, compared with corresponding results for viscous flow of the solvents, and inferences drawn about the structure of the solvent and the nature of the relaxation process.The effects of solute dimensions and solvent viscosity upon the relaxation times are examined and an equation proposed to relate these factors.

On the theory of the dielectric constant of dilute solutions of polar molecules in non-polar solvents

The dielectric constant of even a very dilute solution of polar molecules in non-polar solvents depends upon the geometry of how the non-polar molecules are arranged and how the polar molecules are placed relative to them. These are topological effects which the usual semi-macroscopic theories employing continuum approximations are inherently incapable of revealing. Their existence is demonstrated by making a microscopic calculation with classical mechanics in which for simplicity the non-polar molecules are treated as forming a cubic lattice, and in which isotropic harmonic oscillators are used to describe the polarizability. When the dipolar interaction between molecules is included in the second order, different formulas are obtained depending on whether the lattice is simple, body-centred or face-centred cubic, and whether the polar molecule goes in interstitially or at a regular lattice point. In the latter case, the formulas of Onsager and Buckingham are recovered if a lattice sum is arbitrarily rep...

Use of Hydrated Polyphenylene Oxide Sulphonate Ion Exchange Membranes for Artificial Kidneys

ION exchange membranes of hydrated polyphenylene oxide sulphonate 0.2 mil thick have been used successfully to purify brackish water and other aqueous salt solutions by reverse osmosis1. Water permeabilities ranged from 0.02 to 0.5 galmil/foot2-day-atm., with salt rejections of dissolved salts in the range of 70 to 95%. Water permeability was directly proportional to the water content of the membrane. Preliminary investigations with highly polar organic solute molecules which ionize little in water suggest that permeability of these species also increases with increasing water content of the membrane. As the water content of the membrane decreases, interaction of the solute molecule with the membrane functional group becomes important.

Dielectric Relaxation and Molecular Structure. V. Application of the Single Frequency Method to Systems with two Debye Dispersions

Abstract There are four Debye equations for dilute solutions which can be used to determine the relaxation time of a polar solute molecule. This paper offers a critical examination of these equations, especially two representative formulas which are mutually independent. If the solute molecule has a non-rigid configuration and has two relaxation times, τ1 and τ2, for overall and internal rotations, respectively, average relaxation times will be obtained from these equations based on measurements at a single frequency. However, the analysis of this paper shows that under a certain condition (if a proper frequency for the measurement and a suitable equation for the calculation are employed) one may make a crude estimate regarding one of the two relaxation times. Further, the ratio of two relaxation times seems to afford a clue for investigating the mechanism of internal rotation. In addition, Cole-Cole dispersion and atomic polarization problems are also discussed.

The nature of cyclopropane. Its interaction as a solvent with polar solutes

The values of the n.m.r. chemical shifts of suitable substituent groups in some ketones, dimethylformamide, and acetonitrile differ in cyclopropane and cyclohexane solutions in a manner which indicates specific interactions between these polar solute molecules and solvent cyclopropane. These solvent shifts are discussed.

High-resolution proton magnetic resonance spectra of polynuclear heterocycles-II : Benzo [ b] thiophen and dibenzothiophen

Full iterative analyses have been carried out of 60 MHz spectra of benzo [ b] thiophen (I) and of 60 and 100 MHz spectra of dibenzothiophen (II) in acetone and carbon tetrachloride solutions at several concentrations. From the 33 peaks in the spectrum of I, analysed as a six-spin system with appreciable inter-ring coupling between H(3) and H(7) and between H(2) and H(6), 15 parameters were determined and 190 transitions assigned. For II, inter-ring coupling is absent but H(2) and H(3) of the ABCD system have closely similar shifts. Deshielding of protons of I and II in acetone solution relative to carbon tetrachloride is attributed to reaction-field effects; some ordering of the polar solute molecules is suggested. For the thiophen rings in I and II, currents calculated from chemical shifts remote from the CS bonds are comparable with those in benzene. In terms of partial bond fixation, the J 4,5, J 5,6 coupling constants observed in I lead to an aromaticity comparable with that in naphthalene, and J 2,3 of II implies a β-bond equivalence approaching that in fluorene.

Dielectric behaviour of poly(olefine sulphone)s in solution. Part 1.—Dielectric relaxation

The dielectric dispersion and absorption of 0–3 % solutions of poly(hexene-1 sulphone) and poly (2-methylpentene-1 sulphone) in several non-polar solvents have been studied for fractionated samples (text-decoration:overlineMn= 20,000–1,066,000) over the frequency range 102–108 Hz at temperatures from –35 to 44°C. Only one dispersion region was found. The critical frequency was inversely proportional to the degree of polymerization raised to the power 1.5–2.0. The results indicate that relaxation occurs by rotation of the molecule as a whole. The absence of an appreciable second dispersion region at higher frequencies shows that the relaxation time for segmental rotation is probably longer than 10–4 sec. The results are discussed in relation to theories of dielectric relaxation of polar polymer molecules in solution.

On the Theory of Shifts and Broadening of Electronic Spectra of Polar Solutes in Polar Media

When a polar-solute molecule undergoes an electronic transition and forms a state of different polarity, the Franck—Condon principle shows that the new system is first formed in a nonequilibrium thermodynamic state. An expression for the spectral shift and broadening by a series of solvents of differing polarity is derived in the present paper in terms of thermodynamic properties of certain equilibrium distribution systems. For this purpose use is made of a recent particle description of nonequilibrium and equilibrium polar media, which emphasizes functional dependence and avoids, thereby, the usual more specific assumptions. A relation between the broadening and the shift is then deduced under certain conditions. Expressions are also derived for the effect of pressure and temperature on the shift, in terms of the polar contribution to the volume and entropy of solvation, respectively, and for the influence of applied electrical fields. An expression is obtained for the solvent-reversal shift of Brooker in terms of the polarizability difference of the initial and final states of the solute. Introduction of more specific assumptions is then made for purposes of comparison with earlier works, which constitute special cases of the present one, and for estimation of dipole moments and polarizabilities of excited states from spectral and electrical shifts.

Dielectric properties of polar solutes in non-polar solvents at microwave frequencies

The dielectric loss and permittivity of solutions of polar molecules in non-polar solvents have been measured at frequencies 9.2 × 109 c/s and 3.5 × 1010 c/s. At the lower frequency independent determinations of absorption and wavelength were made on solutions of benzophenone over the temperature range 10 to 30° C. At the higher frequency the solute investigated was nitromethane and the temperature range was 10 to 40° C. Values of dipole moments obtained were 2.95 Debye units and 2.855 Debye units for benzophenone and nitromethane respectively.

The Dielectric Relaxation of Polar Molecules in Solution

A simple theory of dielectric relaxation is proposed, based on the same model of a liquid as Andrade's theory of viscosity. It is shown that the relaxation time of a polar molecule in solution in a non-polar solvent should be related, not to the viscosity of the solvent, but to the ` mutual viscosity' of the solute and solvent. This quantity can be calculated from the variation of the viscosity of the solution with concentration, since the viscosity ?m of a mixture containing mole fractions fA and fB of the two substances A and B is shown to be ?m = fA2?A ?A/?m + fB2?B ?B/?m + 2fAfB?AB ?AB/?m where the ?'s are intermolecular distances, and ?AB, the mutual viscosity, represents the contribution to the total viscosity of collisions between a molecule of substance A and a molecule of substance B. The theory shows satisfactory agreement with experimental results both for pure liquids and for solutions.

The kinetics of certain reactions between methyl halides and anions in water

The rates at which methyl chloride, methyl bromide and methyl iodide react with the hydroxyl and the thiosulphate ions in water have been measured at various concentrations and temperatures. The apparent energies of activation in both series increase in the same direction as the dipole moment of the methyl halide. The results are discussed in terms of a theory of the kinetics of the reactions between ions and polar molecules in solution.

The Orientation of Dipole Molecules in a Viscous Medium

In order to explain its variation with temperature and frequency the dielectric constant has been defined as a measure of the work done by an external electrical field in orienting molecules against the effect of their thermal agitation. Quantitative studies of the temperature variation of the dielectric constant of particular kinds of systems have been made and have given quite valuable information concerning the structure of molecules, but corresponding studies of the frequency variation of the dielectric constant have not as yet been so successful. It is the purpose of this article to discuss in some detail what seems to us to be the most important theoretical difficulty. By way of introduction it may be stated that in the case of a polar liquid there is a region in which the dielectric constant decreases with increasing frequency, the frequency region being dependent upon the size of the orienting molecule and the viscosity of the medium. The difficulty to be considered has to do with the manner in which in a solution the actual frictional resistance of the solvent molecules to the rotation of the polar solute molecules has been determined.