1H NMR spectra and conformations of propane-1,2-diol, meso- and racemic butane-2,3-diols, and some alditols in non-aqueous media

Gallwey, F. B.; Hawkes, Jane E.; Haycock, Peter R.; Lewis, David

doi:10.1039/p29900001979

Cited by 31 publications

(32 citation statements)

References 13 publications

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“…This lower frequency absorption was assigned to the presence of an intramolecular hydrogen bond between the two hydroxyl groups. 1 H NMR and 13 C NMR studies 6 performed on 2,3-butanediol confirm the existence of this interaction in solvents of low polarity whereas in more polar solvents there is no evidence of intramolecular H-bond.…”

Section: Introductionmentioning

confidence: 82%

“…Calculated spectra were simulated using Lorentzian functions centered at the calculated (scaled) frequencies and with bandwidth-at-half height equal to 4 cm À1 . The dashed line represents the calculated spectrum due to conformer gG 0 G 0 t (5) in the same abundance (16.2%) as that of conformer tG 0 G 0 g (6). Note the change of the ordinate scale from frame A to frame B.…”

Section: Interpretation Of the Vibrational Spectramentioning

confidence: 99%

“…The latter spectrum simulates the first step of annealing. Asterisks designate positions of bands due to conformer (6). The split of the theoretical spectra into individual components is shown in Fig.…”

Section: Interpretation Of the Vibrational Spectramentioning

confidence: 99%

“…4 Fingerprint region of the experimental infrared spectrum of 1,2-butanediol isolated in a krypton matrix at 10 K (middle frame) compared to two theoretically simulated spectra. The spectrum in the upper frame contains contributions of five conformers: (1), (4), (6), (7), and (9). The spectrum in the lower frame contains contributions of the twenty-two lowest energy forms.…”

Section: Interpretation Of the Vibrational Spectramentioning

confidence: 99%

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Stepwise conformational cooling towards a single isomeric state in the four internal rotors system 1,2-butanediol

Reva

Jesus

Rosado

et al. 2006

Phys. Chem. Chem. Phys.

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The present work explores the possibilities of the matrix isolation technique in the structural characterisation of highly flexible molecules. To date, most studies of this type were carried out on molecules with three or less internal degrees of freedom and a few (less than 10) possible conformations. The molecule of 1,2-butanediol has four conformationally relevant three-fold rotational axes, which can result in 81 possible conformations. A detailed theoretical study, at the MP2 and DFT(B3LYP) levels of theory with the 6-311++G(d,p) basis set, revealed that more than 20 conformers of 1,2-butanediol have relative energies in a 0-10 kJ mol À1 range and contribute appreciably to the gas phase equilibrium at room temperature. This fact renders conformational studies of the system extremely difficult under normal conditions. However, the method of matrix isolation permits the reduction of the number of populated conformational states in the experiment at low temperature due to the effect known as conformational cooling: low energy barriers promote the relaxation of the higher energy local minima into more stable structures. As a result of massive conformational cooling occurring upon matrix deposition, only five conformers of 1,2-butanediol were retained in the samples at 10 K. These conformers were identified using a combination of FTIR spectroscopy and extensive theoretical calculations of vibrational spectra. Annealing of the matrices up to 50 K resulted in the extreme case of conformational cooling related with the depopulation of all conformers into the most stable unique structure. The observed transformations were rationalized in terms of barriers to intramolecular rotation.

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Section: Introductionmentioning

confidence: 82%

Section: Interpretation Of the Vibrational Spectramentioning

confidence: 99%

Section: Interpretation Of the Vibrational Spectramentioning

confidence: 99%

Section: Interpretation Of the Vibrational Spectramentioning

confidence: 99%

See 2 more Smart Citations

Stepwise conformational cooling towards a single isomeric state in the four internal rotors system 1,2-butanediol

Reva

Jesus

Rosado

et al. 2006

Phys. Chem. Chem. Phys.

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“…In the past, structure of diols including 1,2-ED and 1,4-BD in the gas, liquid and solid phases have been studied extensively by different experimental methods such as X-ray, neutron 4,5 and electron diffractions, 6,7 and microwave, 8,9,10 NMR, 11,12,13 and FT-IR spectroscopy. 14,15 The electron diffraction studies on 1,2-ED in the gas phase indicated that the gauche conformer is considerably more stable than the trans because of the presence of the internal hydrogen bonding in the gauche conformer.…”

Section: Introductionmentioning

confidence: 99%

Conformational Stability and Intramolecular Hydrogen Bonding in 1,2-Ethanediol and 1,4-Butanediol

Das

Arunan

2015

J. Phys. Chem. A

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The gas-phase infrared spectra of 1,2-ED and 1,4-BD have been recorded at three different temperatures using a multipass gas cell of 6 m optical path length. DFT calculation has also been carried out using 6-311++G** and aug-cc-pVDZ basis sets to look for the existence of intramolecular hydrogen bonding in them from the red shift and infrared absorption intensity enhancement of the bonded O-H band compared to that of the free O-H band. Equilibrium population analysis with 10 conformers of 1,2-ED and 1,4-BD at experimental temperatures were carried out for the reconstruction of the observed vibrational spectra at that temperature using standard statistical relationships. The most abundant conformer at experimental temperatures was identified. In 1,2-ED a red shift of 45 cm(-1) in the intramolecularly interacting O-H stretching vibrational band position and no significant intensity enhancement compared to that of the free O-H have been observed. On the contrary, in one of the hydrogen-bonded conformers of 1,4-BD, a 124 cm(-1) red shift in the O-H stretching frequency and a 8.5 times intensity enhancement for the "bonded" O-H compared to that of the "free" O-H is seen. On the basis of this comparative study, we have concluded that strong intramolecular hydrogen bonding exists in 1,4-BD. But there appears to be weak intramolecular hydrogen bonding in 1,2-ED at temperatures of 303, 313, and 323 K in the gas phase. We have found that most stable hydrogen-bonded conformers of 1,4-BD are less populated than some of the non-hydrogen-bonded conformers. Even for the 1,4-BD, the relative population of the g'GG'Gt conformer, which has a strong intramolecular hydrogen bond, is less than what is predicted. Perhaps the intramolecular hydrogen bond plays a less significant role in the relative stability of the various conformers than what has been predicted from calculations and prevails in the literature.

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Diastereofacial Selectivity ofO-Protected α-Hydroxy Aldehydes: Temperature and Solvent Effect

et al. 2000

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1H NMR spectra and conformations of propane-1,2-diol, meso- and racemic butane-2,3-diols, and some alditols in non-aqueous media

Cited by 31 publications

References 13 publications

Stepwise conformational cooling towards a single isomeric state in the four internal rotors system 1,2-butanediol

Stepwise conformational cooling towards a single isomeric state in the four internal rotors system 1,2-butanediol

Conformational Stability and Intramolecular Hydrogen Bonding in 1,2-Ethanediol and 1,4-Butanediol

Diastereofacial Selectivity ofO-Protected α-Hydroxy Aldehydes: Temperature and Solvent Effect

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