Enthalpy Difference between Conformers of n-Butane and the Potential Function Governing Conformational Interchange

Herrebout, Wouter A.; Veken, B.J. van der; Wang, Aiying; Durig, J. R.

doi:10.1021/j100002a020

Cited by 286 publications

(187 citation statements)

References 1 publication

Supporting

Mentioning

153

Contrasting

Unclassified

Order By: Relevance

“…[20][21][22][23] The energy barrier predicted for the trans f gauche C R -C internal rotation in propionic acid is closer to those found in propionyl fluoride and propionyl chloride (680-820 cm -1 ) 20,21 rather than to the average values reported for saturated hydrocarbons (1000-1400 cm -1 ). [33][34][35][36] Direct interconversion between the two degenerate gauche configurations of the C-C-C-O moiety (i.e., the T g + fT gor C g + f C g -process) can also take place ( Figure 2). The transition state for these processes corresponds to the syn configuration around the C R -C bond.…”

Section: Computational Resultsmentioning

confidence: 99%

Internal Rotation in Propionic Acid: Near-Infrared-Induced Isomerization in Solid Argon

et al. 2005

View full text Add to dashboard Cite

The conformational system of propionic acid (CH 3 CH 2 COOH) is studied in solid argon. It is predicted by the ab initio calculations that this molecule has four stable conformers. These four structures are denoted T t , T g ( , C t , and C g ( , and they differ by the arrangement around the C-O and C R -C bonds. The ground-state T t conformer is the only form present at 8 K after deposition of an argon matrix containing propionic acid. For the CH 3 CH 2 COOH and CH 3 CH 2 COOD isotopologues, narrow-band excitation of the first hydroxyl stretching overtone of the conformational ground state promotes the C R -C and C-O internal rotations producing the T g ( and C t conformers, respectively. A subsequent vibrational excitation of the produced T g ( form induces its conversion to the C g ( conformer by rotation around the C-O bond. In the dark, all of the produced conformers decay to the conformational ground state at different rates. The decay kinetics and its temperature dependence allow the identification of the conformers by IR absorption spectroscopy, which is supported by ab initio calculations of their vibrational spectra. For the CH 3 CH 2 COOD isotopologue, the excitation of molecules isolated in different matrix sites results in site-dependent photoisomerization rates for the C R -C and C-O internal rotations, which also confirm the identification of the photoproducts.

show abstract

Section: Computational Resultsmentioning

confidence: 99%

Internal Rotation in Propionic Acid: Near-Infrared-Induced Isomerization in Solid Argon

et al. 2005

View full text Add to dashboard Cite

show abstract

“…Rigorously, such a calculation should take into account not only the energy difference between the conformers, but also differences in the partition functions of the isolated molecules. Because the latter entropic effect is relatively small, and because the quality of our correlations is insensitive to small changes in the dipole moment, we used only the energy difference [57] in our calculations.…”

Section: Dipole Momentsmentioning

confidence: 99%

Method for Estimating the Dielectric Constant of Natural Gas Mixtures

Harvey

Lemmon

2005

Int J Thermophys

View full text Add to dashboard Cite

A method has been developed for calculating the static dielectric constant (relative permittivity) of fluid mixtures, with an emphasis on natural gas. The dielectric constant is calculated as a function of temperature, density, and composition; the density is calculated with a fundamental mixture equation of state. Theory-based correlations were developed for the dielectric constant of all significant components of natural gas, including not only light hydrocarbons but also gases such as nitrogen and carbon dioxide. In many cases, these correlations took advantage of new, highly accurate data measured in cross capacitors. For mixtures, the pure-component values are combined as proposed by Harvey and Prausnitz; this produces better results than the traditional mixing rule.

show abstract

“…In nbutane, the experimental value is 3.62 kcal/mol 19 with calculated values being 3.49 20 and 3.31kcal/mol 21,22 . In their work, Mirkin et al found a good agreement between experimental values and MP2/6-31G* rotational barriers which were relatively larger than HF/6-31G* or HF/6-31G ones 18,23 .…”

Section: Hmentioning

confidence: 92%

Theoretical and Spectroscopic investigations of conformations, rotational barriers and scaled vibrations of 2,3-dimethyl hexane

Aboulmouhajir¹,

Mouatarif²,

Hachim³

et al. 2017

Mediterr.J.Chem.,

View full text Add to dashboard Cite

The 2,3-dimethyl hexane conformational isomerism has been investigated in detail, based on HF, Post-HF and DFT calculations at different basis set. The effect of size of basis, ZPE, thermal contributions, electronic correlation and optimization methods on the conformational stability was discussed. The rotational barriers from the most stable conformer to the lowest energy secondary conformers and their correspondent inversion barriers at both HF and MP2 methods using 6-31G* basis set have also been approached. A normal mode calculation of the most and less-stable conformers using a scaled ab initio force field in terms of non-redundant local symmetry coordinates have been made to elucidate the conformational dependence of the vibrational spectra.

show abstract

Enthalpy Difference between Conformers of n-Butane and the Potential Function Governing Conformational Interchange

Cited by 286 publications

References 1 publication

Internal Rotation in Propionic Acid: Near-Infrared-Induced Isomerization in Solid Argon

Internal Rotation in Propionic Acid: Near-Infrared-Induced Isomerization in Solid Argon

Method for Estimating the Dielectric Constant of Natural Gas Mixtures

Theoretical and Spectroscopic investigations of conformations, rotational barriers and scaled vibrations of 2,3-dimethyl hexane

Contact Info

Product

Resources

About