Dielectric properties of hexafluoroacetone and hexachloroacetone

1969 ◽  
Vol 47 (12) ◽  
pp. 2253-2256 ◽  
Author(s):  
R. K. Chan
Keyword(s):  
Dipole Moment ◽  
Dielectric Properties ◽  
Liquid State ◽  
Dipole Moments ◽  
Dielectric Constants ◽  
Pure Liquid ◽  
Gaseous State ◽  
Vector Addition ◽  
Inductive Effects ◽  
Experimental Values

The dielectric constants of hexafluoro- and hexachloro-acetone are measured in the solid and liquid state. They show negligible association in the liquid state. The dipole moments are 0.648 D measured in the gaseous state and 0.63 D in pure liquid for hexafluoroacetone, and 1.24 D in carbon tetrachloride solution and 1.34 D in pure liquid for hexachloroacetone. If the differences between inductive effects due to CX3 and C=O groups can be ignored, the vector addition of bond moments gives values of dipole moment which are compatible with the experimental values.

Experimental and computed dipole moments in donor–bridge–acceptor systems with p-phenylene and p-carboranediyl bridges

2009 ◽  
Vol 74 (1) ◽  
pp. 131-146 ◽  
Author(s):  
Ladislav Drož ◽  
Mark A. Fox ◽  
Drahomír Hnyk ◽  
Paul J. Low ◽  
J. A. Hugh MacBride ◽  
...  
Keyword(s):  
Dipole Moment ◽  
Dipole Moments ◽  
Electronic Effects ◽  
Electronic Interactions ◽  
Donor And Acceptor ◽  
Homo And Lumo ◽  
Pull Systems ◽  
The Difference ◽  
Experimental Values ◽  
2D And 3D

Dipole moments were measured for a series of substituted benzenes, biphenyls, terphenyls, C-monoaryl- and C,C′-diaryl-p-carboranes. For the donor–bridge–acceptor systems, Me2N–X–NO2, where X is 1,4-phenylene, biphenyl-4,4′-diyl, terphenyl and 1,4-C6H4-p-CB10H10C-1,4-C6H4, the measured interaction dipole moments are 1.36, 0.74, 0.51 and 0.00 D, respectively. The magnitude of the dipole moment reflects the ability of the bridge to transmit electronic effects between donor and acceptor groups. Thus, whilst the 1,4-phenylene bridges allow moderate electronic interactions between the remote groups, the p-carboranediyl unit is less efficient as a conduit for electronic effects. Averaged dipole moments computed at the DFT (B3LYP/6-31G*) level of theory from two distinct molecular conformers are in good agreement with the experimental values. Examination of the calculated electronic structures provides insight into the nature of the interactions between the donor and acceptor moieties through these 2D and 3D aromatic bridges. The most significant cooperative effect of the bridge on the dipole moment occurs in systems where there is some overlap between the HOMO and LUMO orbitals. This orbital overlap criterion may help to define the difference between “push-pull” systems in which electronic effects are mediated by the bridging moiety, and simpler systems in which the bridge acts as an electronically innocent spacer unit and through-space charge transfer/separation is dominant.

The Electrostatic Moments of a Charge Distribution

1997 ◽  
Author(s):  
Philip Coppens
Keyword(s):  
Dipole Moment ◽  
Charge Distribution ◽  
Dipole Moments ◽  
Practical Importance ◽  
Diffraction Method ◽  
Quadrupole Moments ◽  
Charge Densities ◽  
Moment Vector ◽  
Experimental Values ◽  
A Charge

The moments of a charge distribution provide a concise summary of the nature of that distribution. They are suitable for quantitative comparison of experimental charge densities with theoretical results. As many of the moments can be obtained by spectroscopic and dielectric methods, the comparison between techniques can serve as a calibration of experimental and theoretical charge densities. Conversely, since the full charge density is not accessible by the other experimental methods, the comparison provides an interpretation of the results of the complementary physical techniques. The electrostatic moments are of practical importance, as they occur in the expressions for intermolecular interactions and the lattice energies of crystals. The first electrostatic moment from X-rays was obtained by Stewart (1970), who calculated the dipole moment of uracil from the least-squares valence-shell populations of each of the constituent atoms of the molecule. Stewart’s value of 4.0 ± 1.3 D had a large experimental uncertainty, but is nevertheless close to the later result of 4.16 ± 0.4 D (Kulakowska et al. 1974), obtained from capacitance measurements of a solution in dioxane. The diffraction method has the advantage that it gives not only the magnitude but also the direction of the dipole moment. Gas-phase microwave measurements are also capable of providing all three components of the dipole moment, but only the magnitude is obtained from dielectric solution measurements. We will use an example as illustration. The dipole moment vector for formamide has been determined both by diffraction and microwave spectroscopy. As the diffraction experiment measures a continuous charge distribution, the moments derived are defined in terms of the method used for space partitioning, and are not necessarily equal. Nevertheless, the results from different techniques agree quite well. A comprehensive review on molecular electric moments from X-ray diffraction data has been published by Spackman (1992). Spackman points out that despite a large number of determinations of molecular dipole moments and a few determinations of molecular quadrupole moments, it is not yet widely accepted that diffraction methods lead to valid experimental values of the electrostatic moments.

Dielectric Properties of Morpholine and Some of Its Derivatives in the Pure Liquid State and in Mixtures with Benzene or Water

1990 ◽  
Vol 94 (2) ◽  
pp. 162-168 ◽  
Author(s):  
A. H. Beine ◽  
A. Lux ◽  
M. Stockhausen ◽  
J. Jadyn ◽  
G. Czechowski ◽  
...  
Keyword(s):  
Dielectric Properties ◽  
Liquid State ◽  
Pure Liquid

scholarly journals Table of Dielectric Constants and Electric Dipole Moments of Substances in the Gaseous State

Physics Today ◽  
1954 ◽  
Vol 7 (6) ◽  
pp. 26-26
Author(s):  
Arthur A. Maryott ◽  
Floyd Buckley
Keyword(s):  
Electric Dipole ◽  
Dipole Moments ◽  
Dielectric Constants ◽  
Electric Dipole Moments ◽  
Gaseous State

scholarly journals Dipole moments and molecular structure. Part I.— A simple resonance method for the measurement of dielectric constants

1932 ◽  
Vol 136 (829) ◽  
pp. 251-255 ◽  
Keyword(s):  
Molecular Structure ◽  
Dipole Moment ◽  
Dipole Moments ◽  
Resonance Method ◽  
Dielectric Constants ◽  
Present Communication ◽  
Dilute Solutions ◽  
Resonance Circuit ◽  
Low Resistance ◽  
Voltage Resonance

Numerous types of resonance methods for the measurement of dielectric constants have been described by different investigators. That detailed in the present communication has no claim to originality, but it is a simple, whilst at the same time reliable, form, which has proved to be very useful for the measurement of the dielectric constants of dilute solutions for the purpose of dipole moment determination. A fairly powerful oscillator is used, enabling the valveless resonance circuit to be some distance removed from it, whilst still receiving ample “pick-up” for the measurements. Resonance in the pick-up circuit is detected by means of a low-resistance thermo-junction, introduced directly into the circuit. The resistance thus introduced does not damp the oscillation unduly. The very small conductivity of the solvent liquids employed does not produce any appreciable error owing to the current resonance not occurring at the same tuning capacity as the voltage resonance.

ChemInform Abstract: Dielectric Properties of Morpholine (Ia) and Some of Its Derivatives (Ib) and (II) in the Pure Liquid State and in Mixtures with Benzene or Water

ChemInform ◽  
1990 ◽  
Vol 21 (19) ◽  
Author(s):  
A. H. BEINE ◽  
A. LUX ◽  
M. STOCKHAUSEN ◽  
J. JADZYN ◽  
G. CZECHOWSKI ◽  
...  
Keyword(s):  
Dielectric Properties ◽  
Liquid State ◽  
Pure Liquid

Principle of additivity of dipole moments: 1,3- and 1,3,5-derivatives of benzene

1985 ◽  
Vol 50 (1) ◽  
pp. 188-199 ◽  
Author(s):  
Juraj Koudelka ◽  
Otto Exner
Keyword(s):  
Dipole Moments ◽  
Bond Angles ◽  
Vector Addition ◽  
Inductive Interaction ◽  
Donor Acceptor ◽  
Experimental Values ◽  
Derivatives Of

Dipole moments of fourteen 1,3-derivatives and thirteen 1,3,5-derivatives of benzene, with axially symmetrical substituents only, were measured in two solvents. After excluding the compounds forming the donor-acceptor complexes with benzene, the experimental values are well reproduced by the vector addition of group moments, i.e. the accuracy achieved is sufficient for practical purposes. Nevertheless, small systematic deviations were observed: the experimental moments were as a rule less than additive in the case of 1,3-derivatives but greater in the case of 1,3,5-derivatives. These deviations cannot be accounted for by deformation of bond angles from the hexagonal geometry but they can be semiquantitatively interpreted by mutual inductive interaction of dipoles. The latter interpretation was supported by CNDO/2 calculations.

Thermodynamic and physical behaviour of some water + polyethyleneglycol mixtures. II. Dielectric properties

1979 ◽  
Vol 57 (6) ◽  
pp. 608-613 ◽  
Author(s):  
Gérard Douhéret ◽  
Maurice Morénas
Keyword(s):  
Dielectric Properties ◽  
Composition Range ◽  
Dipole Moments ◽  
Partial Molar Volumes ◽  
Correlation Factor ◽  
Dielectric Constants ◽  
Treatment Results ◽  
Rich Region ◽  
Physical Behaviour ◽  
Water Lattice

Dielectric constants of water + glycol (mono-, di-, tri-, and tetraethyleneglycol) mixtures have been measured at 298.15 K over the entire composition range. The mixtures involving monoethyleneglycol have also been studied at temperatures from 308.15 to 288.15 K. Calculated deviations from ideality are always positive and show one maximum. Related properties have been computed: polarizability volume and excess polarizability volume, correlation factor of mixtures, and dipole moments of both components using the Mecke–Reuter treatment. Results support conclusions previously deduced from excess and partial molar volumes; they suggest that the addition of glycol molecules gives rise to a slight enhancement of the water-lattice in the water-rich region, followed by a progressive destructuring; the ether functions do not seem to play a prominent role.

Principle of additivity of dipole moments: Halogen derivatives of adamantane

1985 ◽  
Vol 50 (1) ◽  
pp. 200-207 ◽  
Author(s):  
Otto Exner ◽  
Juraj Koudelka
Keyword(s):  
Dipole Moments ◽  
Tetrahedral Geometry ◽  
General Applicability ◽  
Smith Method ◽  
Vector Addition ◽  
Moment Approach ◽  
Experimental Values ◽  
Derivatives Of ◽  
Mutual Induction

Dipole moments of halogenated adamantanes II-IV were measured in two solvents using the Guggenheim-Smith method. The reliability of the method was checked on non-polar symmetrical compounds I, V. The dipole moments of 1,3-dihalogen and 1,3,5-trihalogen derivatives reveal small but real deviations from the additive behaviour: the experimental values are less than those calculated by vector addition from the moments of monoderivatives, assuming tetrahedral geometry. This fact can be explained by mutual induction of dipole rather than by angle deformation, although both effects can contribute. The deviations from the additive behaviour are qualitatively represented by CNDO/2 calculations with fixed geometry. However, even the greatest deviations observed amount only several percent in relative values and do not impair the general applicability of the bond moment approach.

Static and dynamic dielectric properties of aminoalcohols in their pure liquid state and in mixtures with dioxane

1996 ◽  
Vol 69 ◽  
pp. 201-209 ◽  
Author(s):  
S.v. Hornhardt ◽  
M. Stockhausen ◽  
H. Herba ◽  
J. Jadżyn ◽  
G. Czechowski ◽  
...  
Keyword(s):  
Dielectric Properties ◽  
Liquid State ◽  
Pure Liquid
Sign in / Sign up

Export Citation Format

Share Document