Conformational Study of 1-Butanol by the Combined Use of Vibrational Spectroscopy and ab Initio Molecular Orbital Calculations

Ohno, Keiichi; Yoshida, Hiroshi; Watanabe, Hidekazu; Fujita, Takaya; Matsuura, Hiroatsu

doi:10.1021/j100079a007

Cited by 85 publications

(101 citation statements)

References 12 publications

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“…It does not, however, bring the alkoxy group at C-6 close to the cationic center, presumably to avoid interactions with the pseudoaxial C-3 substituent. This conformer would be destabilized not only by syn -butanol interactions,85 but also by bringing two oxygen atoms into proximity 86. In contrast, although both 40 (the O S 2 conformer) and 41 ( 5 H 4 ) place all three substituents in positions to maximize their electrostatic influences, they remain higher in energy than the half-chair conformer 38 .…”

Section: Resultsmentioning

confidence: 98%

The Effect of Electrostatic Interactions on Conformational Equilibria of Multiply Substituted Tetrahydropyran Oxocarbenium Ions

2008

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The three-dimensional structures of dioxocarbenium ions related to glycosyl cations were determined by an analysis of spectroscopic, computational, and reactivity data. Hypothetical low-energy structures of the dioxocarbenium ions were correlated with both experimentally determined 1 H NMR coupling constants and diastereoselectivity results from nucleophilic substitution reactions. This method confirmed the pseudoaxial preference of C-3 alkoxy-substituted systems and revealed the conformational preference of the C-5 alkoxymethyl group. Although the monosubstituted C-5 alkoxymethyl substituent preferred a pseudoequatorial orientation, the C-5-C-6 bond rotation was controlled by an electrostatic effect. The preferred diaxial conformer of the trans-4,5-disubstituted tetrahydropyranyl system underscored the importance of electrostatic effects in dictating conformational equilibria. In the 2-deoxymannose system, although steric effects influenced the orientation of the C-5 alkoxymethyl substituent, the all-axial conformer was favored because of electrostatic stabilization.

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Section: Resultsmentioning

confidence: 98%

The Effect of Electrostatic Interactions on Conformational Equilibria of Multiply Substituted Tetrahydropyran Oxocarbenium Ions

2008

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“…Identification of the lowest energy conformers (LECs) for the hydroxybutyl and butoxy radicals of n-butanol is complicated due to the existence of internal rotational degrees of freedom. Ohno et al 53 identified 14 energetically distinguishable conformers for n-butanol by the combined use of vibrational spectroscopy and ab initio molecular orbital calculations at the 6-31G level. The LEC was found to have the geometry of TGt, where the C−C−C−C dihedral angle is denoted by T (trans), O−C−C−C by G (gauche), and H−O− C−C by t (trans), as shown in Figure 1.…”

Section: Resultsmentioning

confidence: 99%

Ab Initio Kinetics for the Decomposition of Hydroxybutyl and Butoxy Radicals ofn-Butanol

2013

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The decomposition kinetics of the hydroxybutyl and butoxy radicals (C4H9O) arising via H abstraction from n-butanol were studied theoretically with ab initio transition-state-theory-based master equation analyses. Stationary points on the C4H9O potential energy surface were calculated at either the RQCISD(T)/CBS//B3LYP/6-311++G(d,p) level or the RQCISD(T)/CBS//CASPT2/aug-cc-pVDZ level. Unimolecular pressure- and temperature-dependent rate coefficients were calculated over broad ranges of temperature (300-2500 K) and pressure (1.3 × 10(-3) to 10(2) atm) by solving the time-dependent multiple-well master equation. The "well merging" phenomenon was observed and analyzed for its influence on the branching ratios and rate coefficients. The theoretical predictions were compared with the available experimental and theoretical data and any discrepancies were analyzed. The predicted rate coefficients are represented with forms that may readily be used in combustion modeling of n-butanol.

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“…A variety of values are expected between zero (antiparallel alignment) and a maximum of twice the single dipole moment (parallel alignment). To estimate the contribution of a single hydroxyl group for the total dipole moment, we calculated it for 1-butanol, using the most stable conformer of the isolated molecule as obtained by Ohno et al 29 at the HF/ 6-31G level of theory. From this calculation, a value of 2.00 D was obtained.…”

Section: Resultsmentioning

confidence: 99%

Molecular Structure of Butanediol Isomers in Gas and Liquid States: Combination of DFT Calculations and Infrared Spectroscopy Studies

et al. 2003

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Density functional theory (Becke3LYP/6-311++G**) conformational analysis was carried out for all positional butanediol isomers. Taking into account the relative populations of the most stable conformers at 298.15 K, the weighted mean enthalpies of each butanediol isomer in the gas state were computed. Combining these results with the experimental values for the enthalpies of vaporization at 298.15 K, an estimate of the enthalpy of each of the butanediol isomers in the liquid state was obtained and discussed. The insight into the structural changes at the molecular level from the isolated molecule to the condensed state was improved by an infrared spectroscopy study in the OH stretching region, which was carried out for a wide range of concentrations of carbon tetrachloride solutions and pure liquids. The spectroscopic studies essentially confirmed the results derived from the combination of the computational and calorimetric studies.

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Conformational Study of 1-Butanol by the Combined Use of Vibrational Spectroscopy and ab Initio Molecular Orbital Calculations

Cited by 85 publications

References 12 publications

The Effect of Electrostatic Interactions on Conformational Equilibria of Multiply Substituted Tetrahydropyran Oxocarbenium Ions

The Effect of Electrostatic Interactions on Conformational Equilibria of Multiply Substituted Tetrahydropyran Oxocarbenium Ions

Ab Initio Kinetics for the Decomposition of Hydroxybutyl and Butoxy Radicals ofn-Butanol

Molecular Structure of Butanediol Isomers in Gas and Liquid States: Combination of DFT Calculations and Infrared Spectroscopy Studies

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