Dielectric Relaxation of Alkyl Acetates in Aromatic and Aliphatic Solvents at Microwave Frequencies

1972 ◽  
Vol 50 (13) ◽  
pp. 1449-1452 ◽  
Author(s):  
G. P. Srivastava ◽  
P. C. Mathur ◽  
Mrs. Krishna
Keyword(s):  
Dielectric Relaxation ◽  
Dipole Moments ◽  
Relaxation Times ◽  
Strong Interactions ◽  
Dielectric Relaxation Time ◽  
Methyl Ethyl ◽  
Microwave Frequencies ◽  
Aromatic Solvents ◽  
Nonpolar Solvents ◽  
Alkyl Acetates

The dielectric relaxation times and the dipole moments of methyl, ethyl, and amyl acetates are measured in six nonpolar solvents having different viscosities. The dielectric relaxation time is found to increase with the chain length in each nonpolar solvent. The relaxation times in aromatic solvents (benzene and p-xylene) are found to be higher than in carbon tetrachloride, even though the viscosity of the latter is more than that of the aromatic solvents This shows that the dielectric relaxation is not only due to the viscous resistance of the solvent but is also influenced by strong interactions between aromatic solvents and solute molecules.

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.

Dielectric loss measurements for Bis(pentane-2,4-dionato)oxovanadium(IV) in benzene and dioxan

1975 ◽  
Vol 28 (5) ◽  
pp. 1137 ◽  
Author(s):  
MJ Aroney ◽  
RL Angel
Keyword(s):  
Dielectric Loss ◽  
Complex Formation ◽  
Dielectric Relaxation ◽  
Dipole Moments ◽  
Relaxation Times

Dipole moments and dielectric relaxation times determined by dielectric loss measurements are reported for bis(pentane-2,4- dionato)oxovanadium(IV) as a solute in benzene and in dioxan. Evidence is presented for VO(acac)2,dioxan complex formation.

Dielectric studies. Part XX. Molecular relaxation of some heterocyclic amines in dilute solution

1968 ◽  
Vol 46 (14) ◽  
pp. 2369-2372 ◽  
Author(s):  
J. Crossley ◽  
S. Walker
Keyword(s):  
Relaxation Time ◽  
Dipole Moments ◽  
Relaxation Times ◽  
Lone Pair ◽  
Intermolecular Forces ◽  
Dilute Solution ◽  
Microwave Frequencies ◽  
Heterocyclic Molecules ◽  
Dielectric Constant And Loss ◽  
The Difference

Dielectric constant and loss data have been obtained at microwave frequencies for acridine, 4-methyl-pyridine, phthalazine, quinoline, and isoquinoline in both cyclohexane and p-xylene solution. The data have been used to calculate relaxation times and apparent dipole moments. For phthalazine, quinoline, and isoquinoline in cyclohexane at 50 °C the distribution coefficient is zero and their relaxation times are very similar. Although the axes about which these three molecules may relax lead to different volumes being swept out, no variation in relaxation behavior has been detected, and each system can be characterized by one relaxation time. The relaxation times for all the heterocyclic molecules except quinoline and acridine in p-xylene are appreciably longer than in cyclohexane. Relaxation time values appear a sensitive means of detecting the weak molecular interaction between the amine and the p-xylene. The difference in behavior between the quinoline and acridine as opposed to isoquinoline could be attributed to a more appreciable steric effect in the former two, hindering the approach of the π-electrons of the p-xylene molecules to the hybridized lone pair on the nitrogen atom. No interaction is, in fact, detectable in the case of quinoline and acridine. The importance of allowing for weak intermolecular forces, even in dilute solution, when relaxation values are being anticipated, is emphasized.

Dielectric Dispersion Studies of Some Intramolecular Hydrogen Bonded Molecules at Microwave Frequencies

1977 ◽  
Vol 32 (6) ◽  
pp. 604-606 ◽  
Author(s):  
H. D. Purohit ◽  
S. Kumar ◽  
A. D. Vyas
Keyword(s):  
Dielectric Loss ◽  
Complex Plane ◽  
Dipole Moments ◽  
Dielectric Dispersion ◽  
Dielectric Relaxation Time ◽  
Relaxation Processes ◽  
Microwave Frequencies ◽  
Group Rotation ◽  
Intramolecular Hydrogen ◽  
Straight Lines

Abstract The permittivity and dielectric loss of acetyl acetone, benzoyl acetone and dibenzoyl methane have been measured at four microwave frequencies viz., 30.20, 24.50, 18.26, and 9.83 GHz and also at 1 MHz and optical frequency at 35 °C. The permittivity and dielectric loss at different frequen­ cies have been plotted against concentration (wt. fraction). The slopes of these straight lines have been used for the complex plane plots (a″ vs. a′). The complex plane plots for these compounds are Cole-Cole arcs. The dielectric relaxation time (τ0) and distribution parameter (α) have been calculated from these plots. Data have been analysed in terms of two relaxation processes i. e., cor­ responding to overall rotation and group rotation. The dipole moments of these molecules are reported.

ChemInform Abstract: APPARENT DIPOLE MOMENTS AND DIELECTRIC RELAXATION TIMES OF 1,4-BENZOQUINONE AND ITS DERIVATIVES IN SOLUTIONS

1975 ◽  
Vol 6 (8) ◽  
pp. no-no
Author(s):  
TOHRU NAGAI ◽  
HIROAKI TAKAHASHI ◽  
KENITI HIGASI ◽  
LESLIE E. SUTTON ◽  
DAVID WADDINGTON
Keyword(s):  
Dielectric Relaxation ◽  
Dipole Moments ◽  
Relaxation Times

scholarly journals Dielectric Relaxation of Mixtures of N-Methylacetamide and N,N-Dimethylformamide Solved in Benzene Using Microwave Absorption Data

2006 ◽  
Vol 61 (3-4) ◽  
pp. 197-204
Author(s):  
Raman Kumar ◽  
V. S. Rangra ◽  
D. R. Sharma ◽  
N. Thakur ◽  
N. S. Negi
Keyword(s):  
Dielectric Relaxation ◽  
Viscous Flow ◽  
Relaxation Process ◽  
Dipole Moments ◽  
Relaxation Times ◽  
Single Frequency ◽  
Absorption Data ◽  
Dielectric Relaxation Process ◽  
Energy Parameters ◽  
Microwave Techniques

The dielectric relaxation times τ and dipole moments μ of N-methylacetamide (NMA) mixed with N,N-dimethylformamide (DMF) in benzene solutions have been obtained using standard standing wave microwave techniques and Gopala Krishna’s single frequency (9.90 GHz) concentration variational method at 25, 30, 35, and 40 ◦C. The energy parameters (ΔHε , ΔFε , ΔSε ) for the dielectric relaxation process of mixtures with equal amounts of NMA and DMF have been calculated and compared with the corresponding energy parameters (ΔHη , ΔFη , ΔSη ) for the viscous flow. On the basis of the observations it is found that the dielectric relaxation process can be treated as a rate process like the viscous flow. Solute-solute and solute-solvent types of the molecular associations have been predicted

Dipole moment and dielectric relaxation studies in some azo compounds

1982 ◽  
Vol 60 (2) ◽  
pp. 257-260 ◽  
Author(s):  
P. B. K. Sarma ◽  
P. V. G. K. Murthy ◽  
C. R. K. Murty
Keyword(s):  
Dipole Moment ◽  
Solution Method ◽  
Dipole Moments ◽  
Relaxation Times ◽  
Azo Compounds ◽  
Dielectric Anisotropy ◽  
Dilute Solution ◽  
Microwave Frequencies ◽  
Central Group ◽  
Relaxation Studies

Dipole moments (μ) and relaxation times (τ) of seven azo central group liquid crystal compounds have been determined using the dilute solution method at radio and microwave frequencies. The results agree fairly well with the estimated values of the dipole moments. The angle, β, between the direction of the dipole moment and the long axis of the molecule, is determined for each molecule from structural considerations. The predicted sign of the dielectric anisotropy (Δε) from the estimated value of p is confirmed experimentally.

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