The Molecular Structure and Conformation of Gaseous Benzyl Alcohol by Electron Diffraction.

Trætteberg, M.; Østensen, Herta; Seip, Ragnhild; Tørneng, E.; Woldbæk, T.; Strand, T. G.; Sukhoverkhov, V. F.

doi:10.3891/acta.chem.scand.34a-0449

Cited by 29 publications

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“…T he conformational properties of benzyl compounds, C 6 H 5 CH 2 X, with flexible ligands have been the subject of several experimental and theoretical studies [1][2][3][4][5][6][7][8][9][10][11]. When X is an alkyl group, an amine or a halide, the COCOCOX dihedral angle is 90°and the COX bond lies in a plane orthogonal to the benzene ring [12][13][14][15][16][17][18][19].…”

Section: Introductionmentioning

confidence: 99%

“…IR and NMR studies of benzyl alcohol in the condensed phase suggest values of 0°, 60°, or 90° [1,4]. Gas phase electron diffraction studies suggest a value of 54° [5], whereas IR-UV spectroscopic studies suggest that benzyl alcohol has a stable planar conformer with both (CCCO) and (CCOH) Ϸ 0° [3]. Most recently, both UV and IR-UV ion dip spectroscopy studies [22], and REMPI and photoelectron spectroscopy studies [23] have been carried out which conclude that the CCCO dihedral angle of benzyl alcohol lies in the range 35-60°.…”

Section: Introductionmentioning

confidence: 99%

“…The reported electron diffraction data is not very sensitive to the torsion; the authors note that "A planar conformer cannot be excluded at this stage, but the 54°conformer obviously fits the experimental data best" [5].…”

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confidence: 99%

“…The major uncertainty is the nature of the long-range forces that gives rise to this observed dihedral angle. The current explanation, given in the most recent studies of benzyl alcohol, is that of long-range intermolecular bonding between the OH group and the -electron density in the phenyl An electron diffraction study of benzyl alcohol [5] reports a model with a phenyl-CO dihedral angle of ϳ54°. In this study the authors considered a single structure and found a best fit to the experimental data.…”

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confidence: 99%

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Conformational studies of benzyl alcohol and benzyl fluoride

Utzat

Restrepo

Bohn

et al. 2004

Int J of Quantum Chemistry

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ABSTRACT:The conformations of several benzyl compounds, C 6 H 5 CH 2 X, have been characterized by rotational spectra and theoretical structure calculations. We have observed the microwave spectrum of benzyl alcohol and its OD isotopomer at high resolution in a pulsed-jet Fourier transform microwave spectrometer. The spectrum is consistent with an asymmetric stable conformation characterized by a COCOCOO dihedral angle of approximately 60°. The spectrum is strongly perturbed by tunneling interactions. The transitions are split into doublets consistent with tunneling interactions between two equivalent conformational minima. The observed splittings diminish upon deuterium substitution. These observations are similar to those previously reported by us for benzyl fluoride. However, the minimum energy conformation for benzyl fluoride has the COCOF plane orthogonal to the plane of the phenyl ring. This conformation for benzyl fluoride is consistent with a model that minimizes steric repulsion between the fluorine of the OCH 2 F group and the closest hydrogens located on the phenyl ring. For benzyl alcohol, previous studies have suggested a weak attraction between the electrons of the phenyl ring and the substituent OOH group as the explanation for the observed stable conformation. A theoretical analysis of the atomic charges in benzyl alcohol suggests another possible explanation of the observed structure. Atomic charges generated by fits to the electrostatic potential indicate a relatively strong dipole-dipole coupling between the OCOH group in the methylene side chain and the closest OCOH group in the phenyl ring. This results in a nearly planar orientation of the OCOH group in the methylene side chain with the phenyl ring, a conformation that yields the observed COCOCOO dihedral angle.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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confidence: 99%

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confidence: 99%

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Conformational studies of benzyl alcohol and benzyl fluoride

Utzat

Restrepo

Bohn

et al. 2004

Int J of Quantum Chemistry

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“…In benzyl alcohol the internal motion about the exocyclic C-C bond is also facile (7)(8)(9) but is complicated in principle by the possibility of attractive 0-H.. . 7~ interactions (10) or, alternatively, by repulsion between the lone-pair electrons on the oxygen atom and the 7~ electrons of the ring (11,12).…”

Section: ---mentioning

confidence: 99%

Motion about the bond in benzyl OR (R = CH₃, CH₂CH₃, CH(CH₃)₂, C(CH₃)₃). Solvent and substituent dependence

Schaefer¹,

Cox²,

Morier³

et al. 1990

Can. J. Chem.

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The 1H nuclear magnetic resonance spectral parameters of benzyl alkyl ethers (CH3, CH2CH3, CH(CH3)2, and C(CH3)3) in CS2 and acetone-d6 solutions are obtained, as are those for the 3,5-dichloro derivatives (CH3, CH2CH3, and CH(CH3)3) in acetone-d6 solution. The long-range coupling constants between the methylene and para ring protons show that the apparent twofold barrier to rotation about the [Formula: see text] bond is solvent and ring-substituent dependent. The apparent twofold barrier ranges from a vanishing value for benzyl methyl ether in CS2 solution to as much as 4.6 kJ/mol for 3,5-dichlorobenzyl isopropyl ether in acetone-d6 solution. The data imply that, for the free molecules, the conformation of highest energy has the CH2—O bond in a plane perpendicular to that of the phenyl group. Molecular orbital computations with a minimal Gaussian basis set agree that, for benzyl methyl ether in the exo form (the methyl group pointing away from the phenyl moiety), this conformation is the least stable. However, geometry optimization procedures imply that the CH2—O bond is twisted out of the ring plane by 30.3° in the most stable geometry of the exo form. Such procedures for the (distorted) endo form locate another stable conformer, in which the CH2—O bond is twisted out of the phenyl plane by 45°, only 0.25 kJ/mol less stable than the most stable conformer of the exo form. These results, together with some computations for the tert-butyl derivative, are discussed in terms of the theoretical potentials for rotation about the [Formula: see text] bond. The approximate potential surface is rather flat compared to kT at ambient temperatures for the free molecules, consistent with its sensitivity to the medium and to ring substituents. Keywords: 1H NMR, benzyl alkyl ethers; long-range coupling constants in benzyl alkyl ethers; conformations, benzyl alkyl ethers; internal motion, benzyl alkyl ethers; MO computations on benzyl methyl ether.

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Intramolecular Hydrogen Bonds and Conformational Properties of Benzylamine

et al. 2001

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Low potential energy barriers means benzylamine exists in different conformational forms that can easily interconvert; one such form is shown in the picture where τ1=140–320° and τ2=60°. The conformational properties of benzylamine and the low energy vibrational modes are determined by nonbonding interactions (C−H⋅⋅⋅N and N−H⋅⋅⋅π intramolecular hydrogen bonds) as is demonstrated by a combination of high resolution spectroscopic data and high level quantum chemical calculations.

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The Molecular Structure and Conformation of Gaseous Benzyl Alcohol by Electron Diffraction.

Cited by 29 publications

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Conformational studies of benzyl alcohol and benzyl fluoride

Conformational studies of benzyl alcohol and benzyl fluoride

Motion about the bond in benzyl OR (R = CH₃, CH₂CH₃, CH(CH₃)₂, C(CH₃)₃). Solvent and substituent dependence

Intramolecular Hydrogen Bonds and Conformational Properties of Benzylamine

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The Molecular Structure and Conformation of Gaseous Benzyl Alcohol by Electron Diffraction.

Cited by 29 publications

References 0 publications

Conformational studies of benzyl alcohol and benzyl fluoride

Conformational studies of benzyl alcohol and benzyl fluoride

Motion about the bond in benzyl OR (R = CH3, CH2CH3, CH(CH3)2, C(CH3)3). Solvent and substituent dependence

Intramolecular Hydrogen Bonds and Conformational Properties of Benzylamine

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Motion about the bond in benzyl OR (R = CH₃, CH₂CH₃, CH(CH₃)₂, C(CH₃)₃). Solvent and substituent dependence