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A Dielectric Spectroscopic Study of Ethylene Carbonate in Solution

A Dielectric Spectroscopic Study of Ethylene Carbonate in Solution The formation of anti-parallel dimers ((EC)2) of ethylene carbonate (EC) in solution is discussed via dielectric data determined over a frequency range up to 3 THz. Two major dielectric processes have been identified in both benzene (Bz) and dimethyl carbonate (DMC) solutions. The relaxation times were ca. 8 and ca. 20 ps in Bz, and ca. 20 and ca. 40 ps in DMC solution for the two relaxation processes, respectively. The population of monomeric EC was evaluated from the strength of the faster relaxation mode assigned to the rotational mode of monomeric EC. Equilibrium constants (Kd) for the (EC)2 formation in the two solvents were determined as functions of the concentration at room temperature assuming a process, 2EC $ \rightleftharpoons $ (EC)2. The libration of EC molecules was observed as a sharper resonance signal at ca. 1.5 × 1013 s−1 when they existed as monomeric EC rather than in the form of (EC)2 in Bz, whereas the signal was not so sharp in DMC. The fact that the determined Kd values depended on the solvent: 3–7 M−1 in Bz and 0.05–0.1 M−1 in DMC, reveals that the choice of solvent governs the efficiency of (EC)2 formation. The Kd showed reasonable agreement with the previously determined equilibrium constants using Raman scattering techniques. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Bulletin of the Chemical Society of Japan Oxford University Press

A Dielectric Spectroscopic Study of Ethylene Carbonate in Solution

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References (34)

Publisher
Oxford University Press
Copyright
© 2016 The Chemical Society of Japan
ISSN
0009-2673
eISSN
1348-0634
DOI
10.1246/bcsj.20160126
Publisher site
See Article on Publisher Site

Abstract

The formation of anti-parallel dimers ((EC)2) of ethylene carbonate (EC) in solution is discussed via dielectric data determined over a frequency range up to 3 THz. Two major dielectric processes have been identified in both benzene (Bz) and dimethyl carbonate (DMC) solutions. The relaxation times were ca. 8 and ca. 20 ps in Bz, and ca. 20 and ca. 40 ps in DMC solution for the two relaxation processes, respectively. The population of monomeric EC was evaluated from the strength of the faster relaxation mode assigned to the rotational mode of monomeric EC. Equilibrium constants (Kd) for the (EC)2 formation in the two solvents were determined as functions of the concentration at room temperature assuming a process, 2EC $ \rightleftharpoons $ (EC)2. The libration of EC molecules was observed as a sharper resonance signal at ca. 1.5 × 1013 s−1 when they existed as monomeric EC rather than in the form of (EC)2 in Bz, whereas the signal was not so sharp in DMC. The fact that the determined Kd values depended on the solvent: 3–7 M−1 in Bz and 0.05–0.1 M−1 in DMC, reveals that the choice of solvent governs the efficiency of (EC)2 formation. The Kd showed reasonable agreement with the previously determined equilibrium constants using Raman scattering techniques.

Journal

Bulletin of the Chemical Society of JapanOxford University Press

Published: May 27, 2016

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