Gauche effect. Stereochemical consequences of adjacent electron pairs and polar bonds

Wolfe, Saul

doi:10.1021/ar50051a003

Cited by 815 publications

(427 citation statements)

References 76 publications

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“…Nonetheless, several compounds have been reported to display the opposite behavior, with gauche being more stable, which has been called the "gauche effect." 20,21 In particular, this effect was already reported a long time ago in some halogenoethanes. 22,23 The F-112 NMR spectra were measured for a 33% and a 10% solution, and the trans conformer was found to be at a lower energy than the gauche.…”

Section: Introductionmentioning

confidence: 61%

Interplay between intramolecular and intermolecular structures of 1,1,2,2-tetrachloro-1,2-difluoroethane

et al. 2011

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We report on the interplay between the short-range order of molecules in the liquid phase of 1,1,2,2-tetrachloro-1,2-difluoroethane and the possible molecular conformations, trans and gauche. Two complementary approaches have been used to get a comprehensive picture: analysis of neutron-diffraction data by a Bayesian fit algorithm and a molecular dynamics simulation. The results of both show that the population of trans and gauche conformers in the liquid state can only correspond to the gauche conformer being more stable than the trans conformer. Distinct conformer geometries induce distinct molecular short-range orders around them, suggesting that a deep intra-and intermolecular interaction coupling is energetically favoring one of the conformers by reducing the total molecular free energy.

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Section: Introductionmentioning

confidence: 61%

Interplay between intramolecular and intermolecular structures of 1,1,2,2-tetrachloro-1,2-difluoroethane

et al. 2011

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“…It was first observed by Edwards (1955) and developed primarily by Lemieux & Chu (1958) and Lemieux (1959). It is a particular application of the more general gauche effect (Wolfe, 1972) to carbohydrates. The anomeric carbon atom C (1) …”

Section: The Anomeric Effectmentioning

confidence: 99%

Crystallographic studies of carbohydrates

Jeffrey¹

1990

Acta Crystallogr B Struct Sci

151

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The monosaccharides which constitute the monomer units of many important industrial and biological macromolecules are well represented among the 2000 crystal structures of the carbohydrate class 45 of the Cambridge Structural Database. There are few examples of crystal structure analyses of the corresponding acids, but many of their calcium salts and calcium salt complexes. With the exception of the disaccharides and cyclodextrins, the oligosaccharides are not well represented, with less than ten trisaccharides, one tetrasaccharide and one hexasaccharide-iodide complex. Two important conformational factors are the Hassel-Ottar effect and the anomeric effect, both of which have been studied using crystallographic data. Hydrogen bonding is ubiquitous in carbohydrate crystals and generally involves all the hydroxyls as both donors and acceptors, and some of the ring and glycosidic oxygens as acceptors. These hydrogen bonds tend to form finite or infinite chains. In hydrates, these chains are linked through the water molecules to form networks. Cyclic hydrogen-bond systems are observed in the cyclodextrins. Long-chain alkylated carbohydrates provide a large class of thermotropic and lyotropic liquid crystals, and some non-ionic surfactants which have been shown to be useful for membrane-protein solubilization and crystallization.

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“…The preferred conformation of 1,2-disubstituted ethanes and analogous ethane fragments often differ from what would be predicted on steric grounds [1]. On the basis of steric bulk and size these molecules would be expected to be more stable in an anti rather than in a gauche conforma tion, which is true for a large number of molecules.…”

Section: Introductionmentioning

confidence: 90%

“…In addition to the Q-branch progressions the spectrum contains several progressions of strong perpendicular PR ( Z l J = l , A K -i = - 1) and RP {A J = -1, AK-\ = 1) transitions. The RP transi tions occur in nearly degenerate pairs of…”

Section: Microwave Spectrummentioning

confidence: 99%

Microwave Spectrum of 1-Butene Oxide

Ljunggren

Mjöberg

Bäckvall

1978

Zeitschrift Für Naturforschung A

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The microwave spectrum of 1-butene oxide in the gas phase has been studied in the frequency region 18.0-39.0 GHz. The spectrum observed arose from a rotamer with a dihedral H-C2-C3-C4 angle of 59° ± 1°. In addition to several ^-branch progressions the spectrum contained several long perpendicular RP and PR progressions. However, of the ground state lines, only the inter mediate PR transitions showed internal rotation splittings that could be resolved to yield a barrier height of 3.02 kcal mol-1. The value derived from the line splittings of the first excited methyl torsional state was slightly higher (3.17 kcal mol-1) but must be regarded as being less reliable. The components of the dipole moment, the rotational constants, and the quartic and sextic centrifugal distortion coefficients for the ground state and three vibrationally excited states were determined.

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Gauche effect. Stereochemical consequences of adjacent electron pairs and polar bonds

Cited by 815 publications

References 76 publications

Interplay between intramolecular and intermolecular structures of 1,1,2,2-tetrachloro-1,2-difluoroethane

Interplay between intramolecular and intermolecular structures of 1,1,2,2-tetrachloro-1,2-difluoroethane

Crystallographic studies of carbohydrates

Microwave Spectrum of 1-Butene Oxide

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