Dielectric Relaxation and Intramolecular Rotation in Aliphatic Ketones

1973 ◽  
Vol 51 (16) ◽  
pp. 2671-2675 ◽  
Author(s):  
John Crossley
Keyword(s):  
Dielectric Relaxation ◽  
Relaxation Times ◽  
Dielectric Constants ◽  
Aromatic Ketones ◽  
Paraffin Oil ◽  
Aliphatic Ketones ◽  
Intramolecular Rotation ◽  
Static Dielectric Constants ◽  
Viscosity Dependence

Dielectric constants and losses have been obtained for a number of aliphatic and aromatic ketones in cycloexane, n-hexadecane, decalin and paraffin oil – cyclohexane mixtures at up to ten frequencies between 1 and 145 GHz at 25 °C. Static dielectric constants have also been measured at 2 MHz. The results for each system have been analyzed in terms of a Cole–Cole distribution. The relaxation times and their viscosity dependence are discussed in terms of dipole reorientation by intramolecular and whole molecule rotations.

scholarly journals Molecular Interactions and Dielectric Relaxation in the Mixtures of Amines with 2-Fluorobenzoic Acid in 1, 4-Dioxane

2019 ◽  
Vol 9 (1) ◽  
pp. 2866-2870
Keyword(s):  
Relaxation Time ◽  
Dielectric Relaxation ◽  
Relaxation Times ◽  
Angular Frequency ◽  
Dielectric Constants ◽  
Intramolecular Interactions ◽  
Dielectric Parameters ◽  
Molar Ratios ◽  
Group Rotation ◽  
Static Dielectric Constants

For the present study, the estimation of the static dielectric constants (0 ), dielectric constant () at an angular frequency and dielectric loss () of methyl, ethyl and propyl amines with 2-fluorobenzoic acid in 1,4-dioxane were carried using Klystron microwave bench at frequency 9.43GHz. Using the dielectric parameters, the overall relaxation time (1 ) and group rotation relaxation time (2 ) of the polar solute molecules and average relaxation times (0 ) were also determined using Higasi and Gopalakrishna method employing Debye’s equations. The obtained results revealed that, out of five different molar ratios, relaxation time () is maximum at 1:1 molar concentration for all the systems due to inter and intramolecular interactions through hydrogen bonding. In addition, the dipole moment, activation viscous flow (f) and dielectric relaxation (f ) due to molar free energy also been discussed.

Dielectric relaxation of some aliphatic ester molecules in solutions

1979 ◽  
Vol 57 (7) ◽  
pp. 1035-1038 ◽  
Author(s):  
M. P. Madan
Keyword(s):  
Relaxation Time ◽  
Dielectric Relaxation ◽  
Relaxation Times ◽  
Activation Parameters ◽  
Dielectric Absorption ◽  
Aliphatic Ketones ◽  
Dielectric Data ◽  
Aliphatic Ester ◽  
Aliphatic Esters ◽  
Intramolecular Rotation

The dielectric absorption of several aliphatic esters has been examined in the microwave region over a range of temperatures in n-heptane, cyclohexane, and benzene. The relaxation times and the thermodynamic parameters have been determined using the measured dielectric data. The values of the relaxation time for those solutions for which there are available known data agree well with other determinations. The relaxation times and the various molar activation parameters have been discussed in terms of dipole reorientation by molecular and intramolecular rotation. It would appear that the relaxation behavior of aliphatic esters is similar to that for other aliphatic molecules, such as aliphatic ketones studied previously.

Relaxation processes of some simple aliphatic molecules in dilute solutions

1977 ◽  
Vol 55 (4) ◽  
pp. 297-301 ◽  
Author(s):  
M. P. Madan
Keyword(s):  
Carbon Tetrachloride ◽  
Dielectric Relaxation ◽  
Thermodynamic Parameters ◽  
Relaxation Times ◽  
Relaxation Processes ◽  
Dilute Solutions ◽  
Microwave Region ◽  
Nonpolar Solvents ◽  
Dielectric Data ◽  
Intramolecular Rotation

The dielectric relaxation processes of acetone, cyclohexanone, 4-methyl-2-pentanone, and 4-heptanone in dilute nonpolar solvents, n-heptane, cyclohexane, benzene, and carbon tetrachloride have been studied in the microwave region over a temperature range 10 to 60 °C. The relaxation times and the thermodynamic parameters for the activated states have been determined using the measured dielectric data. The results have been discussed in terms of dipole reorientation by molecular and intramolecular rotation and compared, wherever possible, with other similar studies on aliphatic molecules.

Macroscopic viscosity and the dielectric relaxation of some substituted benzenes

1976 ◽  
Vol 54 (9) ◽  
pp. 1418-1424 ◽  
Author(s):  
S. C. Srivastava ◽  
J. Crossley
Keyword(s):  
Relaxation Times ◽  
Dielectric Constants ◽  
The Other ◽  
Relaxation Processes ◽  
Substituted Benzenes ◽  
Microwave Dielectric ◽  
Paraffin Oil ◽  
Oil Mixtures ◽  
Insight Into ◽  
Dielectric Results

Microwave dielectric constants and losses, and viscosities (η) have been obtained for acetophenone, anisole, bromobenzene, and p-dimethoxybenzene in n-heptane, n-hexadecane, paraffin oil, and three n-heptane + paraffin oil mixtures between 15 and 60 °C. The dielectric results have been analyzed for mean relaxation times (τ0). Plots of ln τ0T against ln η for bromobenzene are compared with those for the other solutes in an attempt to determine the effect of contributions from intramolecular relaxation processes. The results suggest that measurements employing several solvents at one temperature provide a better insight into mechanisms of dipole reorientation than those with one solvent at several temperatures.

THE DIELECTRIC PROPERTIES OF METHANOL AND METHANOL-d

1957 ◽  
Vol 35 (5) ◽  
pp. 458-473 ◽  
Author(s):  
D. W. Davidson
Keyword(s):  
Dielectric Properties ◽  
Room Temperature ◽  
Freezing Point ◽  
Relaxation Times ◽  
Dielectric Constants ◽  
Gradual Transition ◽  
Kcal Mole ◽  
Limited Temperature ◽  
Limited Temperature Range ◽  
Static Dielectric Constants

The dielectric properties of methanol and methanol-d were examined between liquid nitrogen and room temperature at frequencies between 40 and 106 cycles per second. In addition to the large increase in the dielectric constant within solid CH3OH at 159.6°K., there is evidence of a further, gradual transition at about 155°K. Similar changes in CH3OD occur at 163.2° and about 157°K. Dispersion processes within the solid are discussed in terms of misaligned crystallites and polarization at the interfaces between crystallites and between regions of solid and liquid. Conductance maxima near 130°K. are tentatively related to the methanol–water eutectic. Static dielectric constants of liquid CH3OD are a little lower than those of CH3OH, while relaxation times over a limited temperature range above the freezing point are some 35% higher; the activation energies for dielectric relaxation of the two molecules in the liquid state are approximately the same (3.5 kcal./mole).

Dielectric Relaxation of the Butyl Alcohols in p-Xylene Solution

1971 ◽  
Vol 49 (5) ◽  
pp. 712-718 ◽  
Author(s):  
John Crossley
Keyword(s):  
Dielectric Relaxation ◽  
Relaxation Times ◽  
Alcohol Concentration ◽  
Dielectric Constants ◽  
Pure Liquid ◽  
Frequency Range ◽  
Concentrated Solutions ◽  
Polar Solvents ◽  
Symmetrical Distribution ◽  
Xylene Solution

Dielectric constants and losses of the four butyl alcohols have been measured at concentrations of 0.02–0.12 mol fraction in p-xylene solution over the frequency range 1–35 GHz at 25 °C. The data for the most dilute solutions can be represented by a symmetrical distribution of relaxation times. For the mole concentrated solutions the Cole–Cole plots indicate a separation into two absorption regions and the data can be analyzed in terms of two relaxation times both of which lengthen with increased alcohol concentration. The contribution from the long relaxation time and the apparent dipole moment for each butanol, is independent of alcohol concentration and decreases in the order n-butanol > iso-butanol > sec-butanol > t-butanol. The results are discussed in terms of previous dielectric relaxation studies of pure liquid aliphatic alcohols and their solutions in non-polar solvents.

Dielectric Relaxation Studies of Silver Nanoparticles dispersed Liquid Crystal

2015 ◽  
Vol 8 (3) ◽  
pp. 2176-2188 ◽  
Author(s):  
Keisham Nanao Singh
Keyword(s):  
Activation Energy ◽  
Silver Nanoparticles ◽  
Liquid Crystal ◽  
Dielectric Relaxation ◽  
Relaxation Process ◽  
Relaxation Times ◽  
Low Frequency ◽  
Bulk Liquid ◽  
Molecular Rearrangement ◽  
Relaxation Studies

This article reports on the Dielectric Relaxation Studies of two Liquid Crystalline compounds - 7O.4 and 7O.6 - doped with dodecanethiol capped Silver Nanoparticles. The liquid crystal molecules are aligned homeotropically using CTAB. The low frequency relaxation process occurring above 1 MHz is fitted to Cole-Cole formula using the software Dielectric Spectra fit. The effect of the Silver Nanoparticles on the molecular dipole dynamics are discussed in terms of the fitted relaxation times, Cole-Cole distribution parameter and activation energy. The study indicate a local molecular rearrangement of the liquid crystal molecules without affecting the order of the bulk liquid crystal molecules but these local molecules surrounding the Silver Nanoparticles do not contribute to the relaxation process in the studied frequency range. The observed effect on activation energy suggests a change in interaction between the nanoparticles/liquid crystal molecules.

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