Conformational analysis of symmetric carbonic acid esters by quantum chemical calculations and dielectric measurements

Labrenz, Detlef; Schröer, Wolffram

doi:10.1016/0022-2860(91)85078-h

Cited by 16 publications

(19 citation statements)

References 34 publications

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“…All of the xctx conformers were found to have relative energies in a narrow interval 10.5–12 kJ·mol –1 . Such results are in reasonable agreement with previous studies. , …”

Section: Resultssupporting

confidence: 94%

“…The experimental frequencies are in a reasonable agreement with those calculated in this work. According to previous experimental as well as theoretical studies, ,− three stable conformers of dimethyl carbonate can be formed due to the hindered rotation around the (OC)–O(R) bonds. The lowest energy conformer is generally denoted as cis–cis determining the dihedral angle between carbonyl and methoxy groups.…”

Section: Resultsmentioning

confidence: 99%

“…Only incomplete vibrational assignments can be found in the literature , for diethyl carbonate. A few studies concerning the conformational analysis of diethyl carbonate were published , which conclude that the conformers having the tt (in original papers cis–cis) configuration around the carbonyl group are preferred in the gaseous phase. In this work, the conformational analysis was carried out based on the three possible configurations (tt, ct, and nn) around the carbonyl group as in the case of dimethyl carbonate.…”

Section: Resultsmentioning

confidence: 99%

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Vapor Pressures and Thermophysical Properties of Dimethyl Carbonate, Diethyl Carbonate, and Dipropyl Carbonate

et al. 2017

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In this work, a thermodynamic study of important industrial solvents, dimethyl carbonate (CAS RN: 616-38-6), diethyl carbonate (CAS RN: 105-58-8), and dipropyl carbonate (CAS RN: 623-96-1), is presented. The vapor pressure pressure measurements were performed using the static method in the temperature interval 238−308 K. Heat capacities of condensed phases were measured by Tian−Calvet calorimetry in the temperature interval 260−358 K. The phase behavior was investigated by DSC in the temperature interval 183− 300 K. The thermodynamic properties in the ideal gaseous state were calculated using the methods of statistical thermodynamics based on calculated fundamental vibrational frequencies and molecular structure data. Calculated ideal-gas heat capacities and experimental data on vapor pressures, condensed phase heat capacities, and vaporization enthalpies were treated simultaneously to obtain a consistent thermodynamic description.

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“…All of the xctx conformers were found to have relative energies in a narrow interval 10.5–12 kJ·mol –1 . Such results are in reasonable agreement with previous studies. , …”

Section: Resultssupporting

confidence: 94%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

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Vapor Pressures and Thermophysical Properties of Dimethyl Carbonate, Diethyl Carbonate, and Dipropyl Carbonate

et al. 2017

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“…By assuming values for the dipole moments, *H¡ between the cisÈcis and cisÈtrans conformers was found to be 10.0(8) kJ mol~1, while *H¡ between the cisÈcis and transÈtrans conformers was found to be 17 kJ mol~1. The original gas and liquid phase dielectric measurements were recently re-analysed by Labrenz et al,4 and these authors conclude the presence of only cisÈcis and cisÈtrans conformers. The results lead to values for the dipole moments of the conformers and to a gas phase energy di †erence of 10.9 kJ mol~1.…”

Section: Introductionmentioning

confidence: 97%

On the conformational behavior of dimethyl carbonate

Bohets¹,

Veken²

1999

Phys. Chem. Chem. Phys.

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Infrared (4000È50 cm~1) spectra of the vapor, the amorphous and crystalline solid phase, and Raman spectra (4000È50 cm~1) of the vapor, liquid and crystalline solid phases of dimethyl carbonate have been recorded, and assignments are proposed. MP2 and DFT ab initio calculations were carried out using a 6-31G** basis set. The calculations show that the compound can occur as the cisÈcis, cisÈtrans and near-transÈnear-trans conformers, with the cisÈcis being the global minimum. Vibrational frequencies and solvation free enthalpies were predicted on the DFT level of theory. Both cisÈcis and cisÈtrans conformers were identiÐed in the vibrational spectra of all Ñuid phases. The enthalpy di †erence between them was determined to be 8.0(4) kJ mol~1 in the pure liquid phase and 13.6(9) kJ mol~1 in the vapor phase.

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“…Other previous theoretical studies are also available. 15,16 The harmonic frequencies for all the vibrational modes were determined at different levels of theory by Sun et al 15 .…”

Section: Introductionmentioning

confidence: 99%

Theoretical Characterization of Dimethyl Carbonate at Low Temperatures

et al. 2015

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Highly correlated ab initio methods (CCSD(T) and RCCSD(T)-F12) are employed for the spectroscopic characterization of the gas phase of dimethyl carbonate (DMC) at low temperatures. DMC, a relevant molecule for atmospheric and astrochemical studies, shows only two conformers, cis-cis and trans-cis, respectively, of C2v and Cs symmetries. cis-cis-DMC represents the most stable form. Using RCCSD(T)-F12 theory, the two sets of equilibrium rotational constants have been computed to be Ae = 10 493.15 MHz, Be = 2399.22 MHz, and Ce = 2001.78 MHz (cis-cis) and to be Ae = 6585.16 MHz, Be = 3009.04 MHz, and Ce = 2120.36 MHz (trans-cis). Centrifugal distortions constants and anharmonic frequencies for all of the vibrational modes are provided. Fermi displacements are predicted. The minimum energy pathway for the cis-cis → trans-cis interconversion process is restricted by a barrier of ∼3500 cm(-1). DMC displays internal rotation of two methyl groups. If the nonrigidity is considered, the molecule can be classified in the G36 (cis-cis) and the G18 (trans-cis) symmetry groups. For cis-cis-DMC, both internal tops are equivalent, and the torsional motions are restricted by V3 potential energy barriers of 384.7 cm(-1). trans-cis-DMC shows two different V3 barriers of 631.53 and 382.6 cm(-1). The far-infrared spectra linked to the torsional motion of both conformers are analyzed independently using a variational procedure and a two-dimensional flexible model. In cis-cis-DMC, the ground vibrational state splits into nine components: one nondegenerate, 0.000 cm(-1) (A1), four quadruply degenerate, 0.012 cm(-1) (G), and four doubly degenerate 0.024 cm(-1) (E1 and E3). The methyl torsional fundamentals are obtained to lie at 140.274 cm(-1) (ν15) and 132.564 cm(-1) (ν30).

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Conformational analysis of symmetric carbonic acid esters by quantum chemical calculations and dielectric measurements

Cited by 16 publications

References 34 publications

Vapor Pressures and Thermophysical Properties of Dimethyl Carbonate, Diethyl Carbonate, and Dipropyl Carbonate

Vapor Pressures and Thermophysical Properties of Dimethyl Carbonate, Diethyl Carbonate, and Dipropyl Carbonate

On the conformational behavior of dimethyl carbonate

Theoretical Characterization of Dimethyl Carbonate at Low Temperatures

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