Relaxation processes of quinoline, isoquinoline, and their mixtures

1980 ◽  
Vol 58 (1) ◽  
pp. 20-24 ◽  
Author(s):  
M. P. Madan
Keyword(s):  
Thermodynamic Parameters ◽  
Molecular Motion ◽  
Polar Solvent ◽  
Relaxation Times ◽  
Relaxation Processes ◽  
Polar Components ◽  
Dielectric Absorption ◽  
System A ◽  
Dielectric Data ◽  
Activated State

The dielectric absorption of quinoline, isoquinoline, and their binary mixtures has been studied in the microwave region over a range of temperatures in dilute benzene and n-heptane solutions. The relaxation times and the thermodynamic parameters for the activated state have been determined using the measured dielectric data. The results obtained have been discussed in terms of the molecular motion of the system. A relation has been proposed to represent the relaxation behavior of a system of two Debye-type polar components in a non-polar solvent. The relation has been tested by comparing the calculated values with those determined experimentally for a few systems consisting of similar, simple rigid polar molecules.

Dielectric relaxation of nitromethane, some nitriles, and their mixtures in dilute solutions

1987 ◽  
Vol 65 (12) ◽  
pp. 1573-1576 ◽  
Author(s):  
M. P. Madan
Keyword(s):  
Refractive Index ◽  
Dielectric Relaxation ◽  
Thermodynamic Parameters ◽  
Molecular Motion ◽  
Empirical Relation ◽  
Relaxation Times ◽  
Relaxation Behaviour ◽  
Polar Components ◽  
Dielectric Absorption ◽  
Activated State

The dielectric absorption of nitromethane, benzonitrile, and acetonitrile and their binary mixtures has been studied in the microwave region over a range of temperatures in dilute benzene solutions. The data on static and optical permittivities at 20 °C have also been obtained, from measurements at 100 kHz and from measuring the refractive index for sodium-D lines, for a few cases. These data have been used to determine the relaxation times and the thermodynamic parameters for the activated state. The results obtained have been discussed in terms of the molecular motion of the systems. A new empirical relation has been proposed to represent the relaxation behaviour of a system of two Debye-type polar components in a nonpolar solvent. The relation has been tested, along with a previously suggested relation, by comparing the calculated values with those determined experimentally.

Microwave Absorption and Relaxation Processes of Some Monosubstituted Benzenes and their Mixtures

1973 ◽  
Vol 51 (17) ◽  
pp. 1815-1822 ◽  
Author(s):  
M. P. Madan
Keyword(s):  
Reasonable Agreement ◽  
Molecular Motion ◽  
Relaxation Times ◽  
Liquid Mixtures ◽  
Polar Component ◽  
Relaxation Processes ◽  
Simple Liquid ◽  
Dielectric Absorption ◽  
Dielectric Data ◽  
Monosubstituted Benzenes

The dielectric absorption of benzene solutions of some monosubstituted benzenes and their mixtures has been studied in the microwave region over a temperature range 6 to 60 °C. The relaxation times and the thermodynamic parameters for the activated states have been determined using the measured dielectric data. The results obtained have been discussed in terms of the molecular motion of the system. The values of relaxation time for single polar component solutions are in reasonable agreement at temperatures at which there are available known data. The relaxation times for the mixtures are consistent with the results obtained by other workers for simple liquid mixtures of polar molecules in dilute solutions which they investigated.

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.

Microwave Absorption and Relaxation Behavior of Some Simple Ketones in Dilute Solutions

1975 ◽  
Vol 53 (1) ◽  
pp. 23-28 ◽  
Author(s):  
M. P. Madan
Keyword(s):  
Relaxation Time ◽  
Thermodynamic Parameters ◽  
Microwave Absorption ◽  
Reasonable Agreement ◽  
Relaxation Times ◽  
Relaxation Behavior ◽  
The Other ◽  
Dielectric Absorption ◽  
Dielectric Data ◽  
Thermodynamic Processes

The dielectric absorption of solutions of 2-hexanone, 4- and 5-nonanone, and 2-decanone 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 for the activated states have been determined using the measured dielectric data. The values of relaxation time are in reasonable agreement at the temperature at which there are available known data. Both the relaxation behavior and the thermodynamic processes are discussed and, where possible, compared with corresponding results of the other workers.

The dielectric behaviour of dipolar mixtures I: chlorobenzene–nitrobenzene mixtures

1986 ◽  
Vol 64 (11) ◽  
pp. 1534-1536 ◽  
Author(s):  
F. F. Hanna ◽  
K. N. Abdel-Nour ◽  
A. M. Ghoneim
Keyword(s):  
Relaxation Time ◽  
Thermodynamic Parameters ◽  
Relaxation Times ◽  
Dielectric Behaviour ◽  
Dilute Solutions ◽  
Single Relaxation Time ◽  
Microwave Region ◽  
Dielectric Absorption

The dielectric absorption of dilute solutions of nitrobenzene, chlorobenzene, and their mixtures in cyclohexane and Decalin® have been measured in the microwave region at three temperatures between 20 and 40 °C. The relaxation times and thermodynamic parameters are determined. A single relaxation time is found for the mixtures, and the results are discussed.

Dielectric studies. Part XXV. Methoxy group rotation in anisole and three para-substituted anisoles

1969 ◽  
Vol 47 (24) ◽  
pp. 4645-4650 ◽  
Author(s):  
D. B. Farmer ◽  
S. Walker
Keyword(s):  
Relaxation Process ◽  
Methoxy Group ◽  
Relaxation Times ◽  
Pure Liquid ◽  
Relaxation Processes ◽  
Molecular Relaxation ◽  
Microwave Frequencies ◽  
Dielectric Absorption ◽  
Weight Factors ◽  
Group Rotation

The dielectric absorption at several microwave frequencies of anisole, p-methylanisole, and p-bromoanisole in the solvent p-xylene, and p-dimethoxybenzene in the solvent cyclohexane has been investigated at 4 to 6 temperatures. Anisole, p-methylanisole, and p-dimethoxybenzene were all found to relax mainly by methoxy group rotation, whereas the relaxation process in p-bromoanisole was very largely molecular relaxation. In the literature, considerable divergence exists for the analyses of the dielectric data of anisole and substituted anisoles into contributions from two relaxation times and the magnitude of the weight factors governing each relaxation process. Such divergencies have been explored and justifiable analyses established for these systems where the weight factors governing the relaxation processes are shown to be roughly of the same order as those estimated from group moment data. The weight factor for molecular relaxation in the pure liquid appears considerably greater than that for a dilute solution of it in a non-polar solvent.

Dielectric studies. Part XVII. Relaxation processes and corresponding enthalpies of activation of some mono-substituted benzenes

1968 ◽  
Vol 46 (6) ◽  
pp. 841-845 ◽  
Author(s):  
J. Crossley ◽  
S. Walker
Keyword(s):  
Relaxation Times ◽  
Molecular Size ◽  
Relaxation Processes ◽  
Dielectric Studies ◽  
Molecular Reorientation ◽  
Substituted Benzenes ◽  
Microwave Frequencies ◽  
Dielectric Absorption ◽  
Expected Increase ◽  
Xylene Solution

The dielectric absorption at several microwave frequencies of liquid ethylbenzene, isopropylbenzene, and phenyltrimethylsilane at 15, 37.5, and 50 °C and cyclohexane solutions of t-butylbenzene and benzotrichloride at 15, 37.5, 45, and 50 °C has been examined. Benzotrichloride has also been studied in cyclohexane and p-xylene solution at 25 °C. Only molecular reorientation can be detected for benzotrichloride, whereas the remainder are all characterized by an absorption that may be analyzed into two relaxation times, one associated with molecular reorientation (τ1) and a shorter relaxation time (τ2) which appears to be attributable to an intermolecular process. The enthalpies of activation of the τ1 process show the expected increase with increasing molecular size, while no temperature dependence is detectable for the shorter relaxation process.

Microwave absorption and dielectric relaxation of some rigid molecules and their mixtures

1977 ◽  
Vol 55 (10) ◽  
pp. 878-883 ◽  
Author(s):  
M. P. Madan ◽  
M. Shelfoon ◽  
I. Cameron
Keyword(s):  
Dielectric Constant ◽  
Relaxation Time ◽  
Loss Factor ◽  
Relaxation Times ◽  
Liquid Mixtures ◽  
Polar Component ◽  
Simple Liquid ◽  
Dielectric Data ◽  
Dielectric Constant And Loss ◽  
Activated State

The dielectric constant and loss factor of some rigid molecules, pyridine, quinoline, and isoquinoline, and their mixtures have been measured in dilute benzene solutions in the microwave region over a range of temperatures. The dielectric data have been used to determine the relaxation times and the thermodynamic parameters for the activated state. The values of the relaxation time for single polar component solutions agree well at temperatures at which there are available known data. The relaxation times for the mixtures are consistent with the results on simple liquid mixtures of polar molecules in dilute solutions which were previously studied by us and by some other workers.

Dielectric relaxation of acetyl- and benzoyl-acetones

1989 ◽  
Vol 67 (5) ◽  
pp. 804-808 ◽  
Author(s):  
R. K. Khanna ◽  
Abha Bhatnagar
Keyword(s):  
Dielectric Relaxation ◽  
Dipole Moments ◽  
Relaxation Times ◽  
Weight Fraction ◽  
Relaxation Mechanism ◽  
Relaxation Processes ◽  
Dielectric Absorption ◽  
Molar Polarization ◽  
Distribution Parameters ◽  
Few Data

Dielectric absorption measurements are reported at radio and microwave frequencies (at six different wavelengths) for acetylacetone and benzoylacetone solutions in benzene, in a temperature range 25–60 °C. Analysis of dielectric data in terms of Cole–Cole arc plots and multiple relaxation processes reveals that, at higher temperatures, overall molecular relaxation is the dominant relaxation mechanism in these β-diketones. The observed relaxation times, distribution parameters, and dipole moments are in reasonable agreement with the few data reported for some temperatures, in the literature. The activation energy parameters are also evaluated assuming dielectric relaxation to be a rate process. Molar polarization vs. weight fraction (concentration) plots show anomalous behaviour for acetylacetone. Keywords: dielectric properties, dielectric losses, relaxation times, dipole moment, dielectric absorption and dispersion, microwave measurements.

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.

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