Dielectric Studies. Part XXXV. Relaxation Studies of Benzaldehyde and Fourpara-Substituted Aideliydes

1974 ◽  
Vol 52 (18) ◽  
pp. 3229-3234 ◽  
Author(s):  
P. F. Mountain ◽  
S. Walker
Keyword(s):  
Hydrogen Bonding ◽  
Relaxation Time ◽  
Intermolecular Hydrogen Bonding ◽  
Dielectric Studies ◽  
Molecular Relaxation ◽  
Relaxation Data ◽  
Dielectric Absorption ◽  
The Mean ◽  
Relaxation Studies ◽  
Xylene Solution

The dielectric absorption has been determined for benzaldehyde, p-fluoro-, p-chloro-, p-bromo-, and p-nitro-benzaldehyde in p-xylene solution at mainly five or six frequencies in the 6.70 to 70.1 GHz region. For all three p-halo-substituents the mean relaxation time values indicate that some mechanism faster than molecular relaxation occurs whereas none was apparent in benzaldehyde itself. A detailed study has been made of p-chlorobenzaldehyde in p-xylene solution at five temperatures, and the data have been analyzed into contributions from a molecular relaxation process and a shorter relaxation time τ2. In the p-xylene solutions of benzaldehyde the relaxation data indicate weak intermolecular hydrogen bonding between the solute and the solvent which is probably of the type [Formula: see text]

Dielectric Studies. Part XXXI. Analysis of the Dielectric Data of Phenol and its Polymerized Forms

1971 ◽  
Vol 49 (7) ◽  
pp. 1106-1114 ◽  
Author(s):  
M. D. Magee ◽  
S. Walker
Keyword(s):  
Dipole Moment ◽  
Relaxation Time ◽  
Mole Fraction ◽  
The State ◽  
Distribution Parameter ◽  
Dielectric Studies ◽  
Microwave Frequencies ◽  
Dielectric Absorption ◽  
Dielectric Data ◽  
Intramolecular Process

The dielectric absorption and dispersions of several solutions of phenol in p-xylene have been measured at four microwave frequencies and at 2 MHz at a temperature of 25 °C. The data have been analyzed in terms of a mean relaxation time, a distribution parameter, and an apparent dipole moment which are useful empirical parameters for assessing the state of aggregation of the phenol molecules. The relaxation time at the lowest practicable concentration (0.02 mole fraction) is long for a molecule expected to relax predominantly by an intramolecular process. This and the behavior of the relaxation time and apparent dipole moment with increasing concentration are considered in terms of a model based on progressive association into an extended series of multimers, the trimer having a zero (or low) dipole moment and higher multimers becoming increasingly flexible.

Dielectric studies. Part XXIII. Relaxation data and apparent dipole moments of aniline and some disubstituted aromatic amines

1969 ◽  
Vol 47 (4) ◽  
pp. 681-686 ◽  
Author(s):  
S. W. Tucker ◽  
S. Walker
Keyword(s):  
Aromatic Amines ◽  
Dipole Moments ◽  
Frequency Dispersion ◽  
Dielectric Studies ◽  
Relaxation Data ◽  
Time Model ◽  
Electric Dipole Moments ◽  
Microwave Frequencies ◽  
Dielectric Absorption ◽  
Dielectric Results

Dielectric studies have been carried out at microwave frequencies on dilute solutions of aniline, p-chloro-, p-bromo-, and m-chloro-anilines, and o-, m-, and p-toluidines at 25 °C in cyclohexane and p-xylene. The static dielectric constant has also been measured at 2 MHz. In addition o- and m-toluidines have been measured at 50 °C and p-toluidine at 15, 35, and 50 °C.The dielectric results, particularly those at 70.01 GHz, establish that there is more than one relaxation process present and the data have been analyzed on a two relaxation time model, the longer of which τ1, is identified as molecular relaxation. The cause of the lower electric dipole moments found from this method as opposed to the non-dielectric absorption methods is discussed. It follows that there is either an additional higher frequency dispersion or (and) a high atomic polarization for aniline and o-, m-, and p-toluidines. Work at still higher frequencies is required to study this further and to establish more precise values of τ2.

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.

Disodium 5,5′-diamino-2,2′-ethylenedibenzenesulfonate tetrahydrate

2007 ◽  
Vol 63 (11) ◽  
pp. m2714-m2714 ◽  
Author(s):  
Stéphane Dufresne ◽  
Michael Gaultois ◽  
W. G. Skene
Keyword(s):  
Hydrogen Bonding ◽  
Geometric Isomer ◽  
Disodium Salt ◽  
Water Molecules ◽  
Intermolecular Hydrogen Bonding ◽  
Π Stacking ◽  
Benzene Rings ◽  
The Mean ◽  
Unsaturated Group

In the title disodium salt, 2Na+·C14H12N2O6S2 2−·4H2O, the two aryl units of the centrosymmetric anion are coplanar. The E geometric isomer was exclusively found, while the mean plane of the unsaturated group is twisted by 10.1 (2)° from the mean plane described by the two aminobenzenes. Four water molecules cocrystallize and participate in intermolecular hydrogen bonding. The anions lie in parallel planes separated by 3.367 (16) Å and their symmetry-related benzene rings are separated by 3.84 (1) Å, leading to weak intermolecular π-stacking.

scholarly journals Crystal structure and synthesis of 3-(1H-pyrrol-2-yl)-1-(thiophen-2-yl)propanone

2018 ◽  
Vol 74 (10) ◽  
pp. 1463-1466 ◽  
Author(s):  
Dáire Gibbons ◽  
Ganapathi Emandi ◽  
Mathias O. Senge
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bonding ◽  
Hydrogen Bonds ◽  
Title Compound ◽  
Previous Literature ◽  
Maximum Deviation ◽  
Intermolecular Hydrogen Bonding ◽  
Compound C ◽  
Ketone Carbonyl ◽  
The Mean

The title compound, C11H9NOS, was obtained in an improved yield compared to previous literature methods. The molecule is essentially planar with a maximum deviation of 0.085 Å from the mean plane through all non-H atoms. There is directive intermolecular hydrogen bonding in the form of N—H...O hydrogen bonds with a distance of 2.889 (3) Å between the pyrrole amine and the ketone carbonyl O atom. The resulting hydrogen-bonding network defines a ribbon parallel to the a axis. These ribbons form offset stacks along the b axis.

scholarly journals Molecular Mobility and Stability Studies of Amorphous Imatinib Mesylate

Pharmaceutics ◽  
2019 ◽  
Vol 11 (7) ◽  
pp. 304 ◽  
Author(s):  
Bożena Karolewicz ◽  
Agata Górniak ◽  
Dominik M. Marciniak ◽  
Igor Mucha
Keyword(s):  
Relaxation Time ◽  
Imatinib Mesylate ◽  
Enthalpy Relaxation ◽  
Attenuated Total Reflectance ◽  
Molecular Relaxation ◽  
Scanning Calorimetry ◽  
Solid Dosage ◽  
Experimental Enthalpy ◽  
Time Parameters ◽  
The Mean

The proposed study examined the characterization and stability of solid-state amorphous imatinib mesylate (IM) after 15 months under controlled relative humidity (60 ± 5%) and temperature (25 ± 2 °C) conditions. After 2 weeks, and 1, 3, 6, and 15 months, the samples were characterized using differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), X-ray powder diffractometry (XRPD), attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR) and scanning electron microscopy (SEM). Additionally, the amorphous form of imatinib mesylate was obtained via supercooling of the melt in a DSC apparatus, and aged at various temperatures (3, 15, 25 and 30 °C) and time periods (1–16 h). Glass transition and enthalpy relaxation were used to calculate molecular-relaxation-time parameters. The Kohlrausch–Williams–Watts (KWW) equation was applied to fit the experimental enthalpy-relaxation data. The mean molecular-relaxation-time constant (τ) increased with decreasing ageing temperature. The results showed a high stability of amorphous imatinib mesylate adequate to enable its use in solid dosage form.

Dielectric studies. Part XVIII. Dipole moments and relaxation times of some symmetrically substituted alkylbenzenes

1968 ◽  
Vol 46 (6) ◽  
pp. 847-851 ◽  
Author(s):  
J. Crossley ◽  
S. Walker
Keyword(s):  
Relaxation Time ◽  
Dipole Moments ◽  
Relaxation Times ◽  
Pure Liquid ◽  
Dielectric Studies ◽  
Molecular Reorientation ◽  
Microwave Frequencies ◽  
Short Relaxation Time ◽  
Dielectric Absorption ◽  
Liquid Benzene

The dielectric absorption at four microwave frequencies of pure liquid benzene and p-cymene at 25 °C, p-xylene and mesitylene at 25, 40, 50, and 60 °C, and solutions of durene and hexamethylbenzene in mesitylene at 60 °C has been examined. All show measurable loss factors and apparent dipole moments of about 0.1 to 0.2 D. These moments are less in magnitude than those associated with the short relaxation time (τ2) process for the polar monoalkylbenzenes. o-xylene and m-xylene. Their relaxation times are too short for molecular reorientation and there is a rough correlation between the number of collisions/molecule s and the reciprocal relaxation time.

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