Influence of Protonation on Internal Rotation of Dimethyl Ether

and, Vojislava Pophristic; Goodman, Lionel

doi:10.1021/jp994359p

Cited by 10 publications

(14 citation statements)

References 24 publications

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“…The internal rotation is defined as the rotation of the methyl groups from the ('' eclipsed, eclipsed '', EE) equilibrium position. 21 The rotation of a single methyl group with a barrier of 2.52 kcal mol À1 (with ZPE) yields the SE confomer (1b) possessing C s symmetry ('' staggered, eclipsed '', SE). The SS (1c) conformer is reached by the simultaneous rotation of both methyl groups by 180 , pre-Fig.…”

Section: Resultsmentioning

confidence: 99%

Theoretical study of hydrogen abstraction from dimethyl ether and methyl tert-butyl ether by hydroxyl radicalElectronic supplementary information (ESI) available: optimized structural parameters, energies, zero point energies and dipole moments for reactants, products, and transition states (Tables S1–8). See http://www.rsc.org/suppdata/cp/b1/b109970c/

Atadinç

Selçuki

Sarı

et al. 2002

Phys. Chem. Chem. Phys.

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31G** and CCSD(T)/6-311++G**//MP2/6-31G** calculations have been used to investigate the H-abstraction reaction from CH 3 OCH 3 (DME) whereas MP2/6-31G**//MP2/6-31G** and PMP2/6-31G**//MP2/6-31G** levels have been used to model the H-abstraction reaction from (CH 3 ) 3 COCH 3 (MTBE) by OH. The methodology used has been proved to be adequate to reproduce the experimental geometrical parameters for the reactants and the C-H bond energies. The reaction rate constants for DME, calculated using the transition state theory reproduce the reported experimental results. The fact that H-abstraction is favored from the methoxy group of MTBE in comparison to the tert-butyl group has also been reproduced.y Electronic supplementary information (ESI) available: optimized structural parameters, energies, zero point energies and dipole moments for reactants, products, and transition states (Tables S1-8). See

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Section: Resultsmentioning

confidence: 99%

Theoretical study of hydrogen abstraction from dimethyl ether and methyl tert-butyl ether by hydroxyl radicalElectronic supplementary information (ESI) available: optimized structural parameters, energies, zero point energies and dipole moments for reactants, products, and transition states (Tables S1–8). See http://www.rsc.org/suppdata/cp/b1/b109970c/

Atadinç

Selçuki

Sarı

et al. 2002

Phys. Chem. Chem. Phys.

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“…Also, the relative energies of all stable conformers of pentane, sec ‐butanol, cyclohexanol, diethyl ether, isopropyl methyl ether, methoxyethanol, and isopropyl formate were included along with the data on low‐energy conformers of THPOH, HMOP, GTHP, and GTHPO. This set was supplemented with reliable experimental data or recently published ab initio energies for ethane,50, 51 butane,42 cyclohexane,52 cyclooctane,53 methylcyclohexane,54 cyclohexanol,32 dimethyl ether,55 ethyl methyl ether,56 oxane,57, 58 dimethoxyethane,59 methyl formate,60 methyl acetate,61 and ethyl formate 62. Finally, torsional profiles and conformational energies for diketones and ketoamides studied by us previously63 were included.…”

Section: Methodsmentioning

confidence: 99%

Parameterization of OPLS–AA force field for the conformational analysis of macrocyclic polyketides

2002

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The parameters for the OPLS-AA potential energy function have been extended to include some functional groups that are present in macrocyclic polyketides. Existing OPLS-AA torsional parameters for alkanes, alcohols, ethers, hemiacetals, esters, and ketoamides were improved based on MP2/aug-cc-pVTZ and MP2/aug-cc-pVDZ calculations. Nonbonded parameters for the sp(3) carbon and oxygen atoms were refined using Monte Carlo simulations of bulk liquids. The resulting force field predicts conformer energies and torsional barriers of alkanes, alcohols, ethers, and hemiacetals with an overall RMS deviation of 0.40 kcal/mol as compared to reference data. Densities of 19 bulk liquids are predicted with an average error of 1.1%, and heats of vaporization are reproduced within 2.4% of experimental values. The force field was used to perform conformational analysis of smaller analogs of the macrocyclic polyketide drug FK506. Structures that adopted low-energy conformations similar to that of bound FK506 were identified. The results show that a linker of four ketide units constitutes the shortest effector domain that allows binding of the ketide drugs to FKBP proteins. It is proposed that the exact chemical makeup of the effector domain has little influence on the conformational preference of tetraketides.

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“…The molecule (CH3)2O belongs to the systems with two internal rotors; the experimental barrier of rotation between A and B forms is 2.60 kcal/mol (near 900 cm −1 ) ( Figure 13) [186][187][188][189]. The origin and nature of the barrier, in particular the role of lone pairs, is widely discussed in the literature [190][191][192][193]. However, in the SWCNT cavity, the conformational behavior of this compound is significantly changed.…”

Section: Dimethyl Ethermentioning

confidence: 99%

Stereochemistry of Simple Molecules inside Nanotubes and Fullerenes: Unusual Behavior of Usual Systems

Кузнецов

2020

Molecules

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Over the past three decades, carbon nanotubes and fullerenes have become remarkable objects for starting the implementation of new models and technologies in different branches of science. To a great extent, this is defined by the unique electronic and spatial properties of nanocavities due to the ramified π-electron systems. This provides an opportunity for the formation of endohedral complexes containing non-covalently bonded atoms or molecules inside fullerenes and nanotubes. The guest species are exposed to the force field of the nanocavity, which can be described as a combination of electronic and steric requirements. Its action significantly changes conformational properties of even relatively simple molecules, including ethane and its analogs, as well as compounds with C−O, C−S, B−B, B−O, B−N, N−N, Al−Al, Si−Si and Ge−Ge bonds. Besides that, the cavity of the host molecule dramatically alters the stereochemical characteristics of cyclic and heterocyclic systems, affects the energy of pyramidal nitrogen inversion in amines, changes the relative stability of cis and trans isomers and, in the case of chiral nanotubes, strongly influences the properties of R- and S-enantiomers. The present review aims at primary compilation of such unusual stereochemical effects and initial evaluation of the nature of the force field inside nanotubes and fullerenes.

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Influence of Protonation on Internal Rotation of Dimethyl Ether

Cited by 10 publications

References 24 publications

Parameterization of OPLS–AA force field for the conformational analysis of macrocyclic polyketides

Stereochemistry of Simple Molecules inside Nanotubes and Fullerenes: Unusual Behavior of Usual Systems

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