Dielectric Constants and Dipole Moments

The temperature in degrees Celsius at which the dielectric constant and dipole moment were measured is shown in this table in parentheses after the value. In some cases, the dipole moment was determined with the substance dissolved in a solvent, and the solvent used is also shown in parentheses after the temperature. 

Revised material for Section 5 includes the material on surface tension, viscosity, dielectric constant, and dipole moment for organic compounds. In order to include more data at several temperatures, the material has been divided into two separate tables. Material on surface tension and viscosity constitute the first table with 715 entries included is the temperature range of the liquid phase. Material on dielectric constant and dipole... 

Correlations among solvent polarity scales, dielectric constant and dipole moment, and a means to reliable predictions of polarity scale values from current data. T. R. Griffiths and D. C. Pugh. Coord. Chem. Rev., 1979, 29,129-211 (130). 

A macroscopic model for regular air/solution interfaces has been proposed by Koczorowski et al 1 The model is based on the Helmholtz formula for dipole layers using macroscopic quantities such as dielectric constants and dipole moments. The model quantitatively reproduces Ax values [Eq. (37)], but it needs improvement to account for lateral interaction effects. 

Both the dielectric constant and dipole moment are comparable to those of water, indicating that HF is a good solvent for inorganic compounds, but many organic compounds are also soluble. In general, the fluorides of +1 metals are much more soluble than those of +2 or +3 metals. At 11 °C, the solubility of NaF is approximately 30 g per 100 g of liquid HF, that of MgF2 is only 0.025 g, and that of A1F3 is 0.002 g. 

C3Hj C(HS. 03, liq, bp 70° at 0.5 mm, d 1.1361 at 20°, d 1-5132 at 20°. Can be prepd by ozonization of allylbenzene using the method of Harries (Ref 1 for oconization of org compds. A detailed description of its prepn is given by Ryffel(Ref 3). Briner et al (Ref 4) detd the following props of allylbenzeneozonide soly in benz, Raman spectra, UV absorption spectra, dielectric constants and dipole moments Note According to Dr H. Walter of PicArs this ozonide is an explosive... 

From these results it would therefore appear that the bulk electrostatic parameters of the solvent, e.g. dielectric constant and dipole moment, do not predict accurately the changes in redox potential that occur in different solvents. 

Dielectric constants and dipole moments were taken from a table in Wikipedia, http //en. 

Continuum solvent models are normally parameterized with the solvent dielectric constant (but see the COSMO models, Chapter 8). First we note that dielectric constant and dipole moment are not in general well correlated from Chapter 8 ... 

TABLE 2-1 Comparison of Equations Relating Dielectric Constant and Dipole Moment... 

Dielectric constant and dipole moment do not incretise together. (See Table 2-II.)... 

The ability to measure the propagation rate in solvents of widely differing dielectric constant and dipole moment, has provided much information on the active species present. In hydrocarbon solvents both the ion-pair and its aggregates are present, viz. 

The possibility of making use of dielectric measurements for the study of the relaxation times is largely dependent on the very polar nature of amino acids, peptides and proteins. We must therefore discuss briefly the relation between dielectric constant and dipole moment in polar liquids, the discussion being for the moment restricted to static fields, or fields of frequency small compared to the rotary diffusion constants of the molecules. 

Dielectric Constants and Dipole Moments of Dipolar Ions. Chap. 6 in... 

The dielectric constants and dipole moment can serve as first indicators for the solvent parameters. Table 2.1 shows that the dielectric constant is low for hydrocarbons and... 

A polarity ranking is not possible based only on dielectric constant and dipole moment because they do not take into account H-bonding thus, polarity series are often constructed empirically, using such factors as the solvent strength parameter obtained from the observed ability of various solvents to elute solutes from aluminum oxide absorbent. However, for environmental chemicals, a numerical index for polarity does not exist only the consequences of polarity, as reflected in measureable properties such as water solubility and octanol-water partition coefficient, are available for fate predictions. 

The dielectric constants needed for the determination of dipole moments are obtained by a heterodyne beat method or the resonance and bridge methods. The instrument specifically adapted for measurements of dielectric constants for dipole moments is a dipole meter model DM-01 manufactured by Wissenschaflich-Technische Werkstatten, Weilheim, Germany, equipped with two different thermostatted cells for two ranges of dielectric constants (cell DFL-1, e 1.0 to 3.4, cell DFL-2, e 2 0 to 6.9). The other dipole meter which used to be available from Toshniwal Brothers, Ltd., Madras, India, is not sufficiently sensitive for measurements of dielectric constants of diluted solutions and is better suited for measurements of large differences, such as the dielectric constants and dipole moments of different solvents. 

We have already described briefly some of the effects of dipole-dipole association. For example, the more strongly solvated an ion or molecule is, the more difficult it is for desolvation to occur so that an active site is exposed. Reactions in which ions are produced as the transition state forms from reactants will usually be accelerated as the solvent dielectric constant and dipole moment increase for a series of solvents. The increased solvation of the ions that constitute the transition state will cause this effect. In contrast, reactions that involve the combination of ions to produce a transition state of low charge will be retarded by solvents that strongly solvate ions. In order for the ions to combine, they must be separated from the solvent molecules, which is energetically unfavorable. 

An interesting extension of this work is provided by the electron spin resonance spectrum of 2-6 di- -butyl-4-methoxymethylphenoxyl (III), which has been recorded in several hydrocarbon solvents all having extremely low dielectric constants and dipole moments. The hyperfine splitting constant of the para-methylene substituent was found to... 

Dielectric constant A simple measure of solvent polarity (the electrostatic factor is a uoduct of dielectric constant and dipole moment). The electrical conductivity of solvent indicates if there is a need to earth (or ground) the equipment which handles solvent to prevent static spark ignition. Admixtures affect solvent conductivity. These are most important in electronics industry. 

The density difference between H2O and D2O can be used for the determination of the deuterium content of heavy water (Schatenstein 1960). It is interesting to note that the 10% difference in density is within 0.5% entirely due to the molecular weight difference. The molar volume of D2O is larger only by 0.34% and that of H2 0 is smaller by 0.15% than the molar volume of H2 0. The isotope effect on the dielectric constant and dipole moment is very small, which plays an important role in the interpretation of solvent isotope effects in aqueous systems (Van Hook 1975). 

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