The Dielectric Properties of Molecular Complexes

Price, A. H.

doi:10.1007/978-1-4684-8471-7_7

Cited by 5 publications

(2 citation statements)

References 90 publications

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“…Using µ w ) 1.84 D from the literature, 42 3.5 D e µ e 3.9 D follows for the dipole moment of the D-glucose molecule in the gaseous state. When compared to estimates for the monosaccharide dipole moments that are based on group moments 43 and bond angles, the evaluation of permittivity data yields a suggestive mean for both D-glucose conformers in water.…”

Section: Discussionmentioning

confidence: 99%

Molecular Dynamics of Carbohydrate Aqueous Solutions. Dielectric Relaxation as a Function of Glucose and Fructose Concentration

2001

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At some solute concentrations c between 1 and 5.4 mol/L, the complex (electric) permittivity of aqueous solutions of D-glucose and D-fructose has been determined as a function of frequency υ between 300 kHz and 40 GHz. The permittivity spectrum of the 5.4 mol/L D-fructose solution has been measured at six temperatures between 10 and 35 °C, and the other spectra have been taken at 25 °C. All dielectric spectra revealed one dispersion/dielectric loss region, which indicated a rather homogeneous relaxation of the solute and solvent dipole moments. Analytically, the measured spectra were represented by the Cole-Cole relaxation spectral function, which corresponds with a continuous, symmetrically bell shaped relaxation time distribution. The parameters of the spectral function are discussed to show that the monosaccharides exhibit unusual hydration properties. Particularly, when treated in terms of a wait-and-switch model of dipole reorientation, the principal dielectric relaxation time is indicative of the extraordinary hydration behavior of the saccharides. It is suggested that this behavior reflects the compatibility of the ring molecule's -OH group topology with the water structure.

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Section: Discussionmentioning

confidence: 99%

Molecular Dynamics of Carbohydrate Aqueous Solutions. Dielectric Relaxation as a Function of Glucose and Fructose Concentration

2001

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“…The dipole moments for −NCO and −OH were taken from the literature. 39 The value of the constant D in eq 20 can be calculated by comparison of the uncatalyzed and catalyzed systems. The rate constant for the uncatalyzed reaction in ethyl acetate was found to be 2.719 × 10 −5 ± 3.799 × 10 −6 L mol −1 s −1 and the rate constant for toluene was found to be 4.950 × 10 −6 ± 6.520 × 10 −7 L mol −1 s −1 .…”

Section: ■ Experimental Sectionmentioning

confidence: 99%

Solvent Effects in Polyurethane Cure: A Model Study

Monaghan

Pethrick

2012

Macromolecules

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The effect of change of solvent type on the rate of cure of a polyol with an isocyanate was measured using a range of different techniques. The initial stages of the cure process were followed using viscosity and Fourier transform infrared spectroscopy [FTIR] measurements. The gelation point was observed using viscosity measurements and depends on the solvent used. FTIR measurements confirm that both acceleration and inhibition of the polyurethane formation occurs with change of solvent. Comparative studies carried using mixtures of ethyl acetate/toluene and n-butyl acetate/xylene are reported. Intrinsic viscosity measurements revealed that the size of the polyol changes with temperature in a different manner depending on the solvent used. In part, the size of the polyol influences the ability for reaction to occur. Measurements of the permittivity, refractive index and solution viscosity indicates that these solvent mixtures deviate from ideality. A model to describe the observed solvent effects is proposed which includes the influence of polarity on the transition state and viscosity on the diffusion of the reactants. Using the measured viscosity and permittivity data for the mixtures, it was possible to obtain a good fit of the experimental data. This study illustrates how the polyurethane reaction is sensitive to the type of solvent used and indicates how the reactivity may be influenced by change in solvent.

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Dielektrizitätskonstante und zwischenmolekulare Wechselwirkungen

Rätzsch

Wohlfarth

1978

Zeitschrift fuer Chemie

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The Dielectric Properties of Molecular Complexes

Cited by 5 publications

References 90 publications

Molecular Dynamics of Carbohydrate Aqueous Solutions. Dielectric Relaxation as a Function of Glucose and Fructose Concentration

Molecular Dynamics of Carbohydrate Aqueous Solutions. Dielectric Relaxation as a Function of Glucose and Fructose Concentration

Solvent Effects in Polyurethane Cure: A Model Study

Dielektrizitätskonstante und zwischenmolekulare Wechselwirkungen

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