The conformation of the unbranched paraffin chain C<sub>22</sub>H<sub>46</sub> in solution as studied by high pressure NMR

Ando, Isao; Inoue, Yoshio

doi:10.1002/marc.1983.030041201

Cited by 6 publications

(5 citation statements)

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“…One of the important molecular level changes in liquids induced by external pressure is conformational changes in the molecules. , In fact, pressure is effective in perturbing the distribution of the conformers of hydrocarbon chain molecules. , Under the condition of high pressure, the conformational preferences are determined principally by the relative volume of the conformers, which is likely to be sensitive to the conformational changes due to folding of alkyl chain. Despite the relevance to understanding many important questions in functional fluids, polymers, and biomembrane lipids, , the pressure-induced conformational changes of hydrocarbon chains ,,, have not been extensively studied. This is mostly due to the insensitivity 27,43 or questionable correspondence , of the conventional experimental parameters to the populations of trans/gauche conformations.…”

Section: Introductionmentioning

confidence: 99%

“…Despite the relevance to understanding many important questions in functional fluids, 27 polymers, 40 and biomembrane lipids, 41,42 the pressure-induced conformational changes of hydrocarbon chains 38,39,43,44 have not been extensively studied. This is mostly due to the insensitivity 27,43 or questionable correspondence 44,45 of the conventional experimental parameters to the populations of trans/gauche conformations.…”

Section: Introductionmentioning

confidence: 99%

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High-Pressure Raman Noncoincidence Effect and Conformation of Alkyl Side Chain in Alkyl Benzoates

et al. 1997

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The Raman noncoincidence effect has been used to investigate the changes in intermolecular interactions induced by applying high pressure to neat liquid alkyl benzoates. The noncoincidence of the carbonyl band of a homologous series of straight chain alkyl benzoates (methyl, ethyl, propyl, butyl, and hexyl benzoate) and a branched chain alkyl benzoate (2-ethylhexyl benzoate) was measured at 20 and 40 °C over the pressure range 1−5000 bar. The density was measured as a function of pressure for all molecules. A transition point dividing the noncoincidence behavior as a function of density into two regions was found, for all molecules except methyl benzoate. Below the transition point, at lower density, the noncoincidence value was relatively insensitive to changes in density, while above the transition point, the noncoincidence value dropped sharply with increasing density. The decrease in the value of noncoincidence above the transition point was interpreted as the change in intermolecular interactions resulting from the conformational change in favor of a “folded” form of the alkyl side chain shielding the carbonyl group. To examine the plausibility of the presence of energetically allowable conformations with a folded alkyl side chain, conformational searches based on molecular mechanics calculations have also been performed. The strain energy of some alkyl benzoate conformers with folded side chain was calculated to be within a few kcal/mol of the global minimum conformation. Both the experimental results and the conformational analysis suggest that the population of the folded conformer increases under high-pressure conditions owing to its compactness.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

High-Pressure Raman Noncoincidence Effect and Conformation of Alkyl Side Chain in Alkyl Benzoates

et al. 1997

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“…The molecular motion of the CHzC12 solvent is considerably restricted in the liquid crystal, and consequently its 'H signal splits into a doublet. 15,16 The sample cell was made from a Pyrex capillary tube with 9-mm o.d., 3-mm i.d., and 180-mm length. Such studies sometimes provide a limited interpretation of the results obtained for the liquid crystal.…”

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confidence: 99%

“…14 The solvent CH2C12 was purified by ordinary distillation. The concentration of the polymer was 15 wt % (PBLG/ CH2C12).…”

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Effect of pressure on the magnetic orientation of the poly(.gamma.-benzyl L-glutamate) liquid crystal as studied by proton NMR under high pressure

Sanefuji¹,

Ando²,

Inoue³

et al. 1985

Macromolecules

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Macromolecules 1985, 18, 583-585 583 specific volume of the polymer, and p e is the mole electron density of the solvent. The value of S,(O) was determined by extrapolation of the plot of S,-l(h) vs h2. The value ijq of polystyrene ( M = 5.0 X lo4) in toluene a t infinite dilution was determined to be 0.919 cm3/g a t 25.0 "C. Figure 1 shows the plot of -(1/V,)c3Ap1/ac vs. polymer concentration c. Since a slight molar mass dependence was observed at low concentrations (c 5 0.05 g/cm3), the results for the highest molar mass alone are shown within this range. The smooth and unambiguous plot allows graphical integration with respect to c to yield the values of Apl at given concentrations. Figure 2 shows the interaction parameter x plotted as a function of the volume fraction &. The values determined from osmotic p r e s s~r e ,~.~ light scattering,2 vapor pressure,8 and sedimentation equilibriumg are also plotted by circles, open triangles, open squares, and filled triangles, respectively, for purposes of comparison. The SAXS result is in good agreement with those obtained by other methods over a wide concentration range. Therefore we conclude that SAXS can provide reliable estimates of the interaction parameter x.

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Some aspects of high‐pressure NMR

Ando

Webb

1986

Magnetic Reson in Chemistry

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Recent advances in the field of high-resolution NMR spectroscopy in both pure liquids and solutions, under high pressure, are reviewed. Experimental techniques employed for making the NMR measurements at high pressures are discussed. An overview of high-pressure NMR studies as applied to intramolecular dynamics, structures of liquids, molecular conformations and intermolecular interactions is presented.

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The conformation of the unbranched paraffin chain C₂₂H₄₆ in solution as studied by high pressure NMR

Cited by 6 publications

References 13 publications

High-Pressure Raman Noncoincidence Effect and Conformation of Alkyl Side Chain in Alkyl Benzoates

High-Pressure Raman Noncoincidence Effect and Conformation of Alkyl Side Chain in Alkyl Benzoates

Effect of pressure on the magnetic orientation of the poly(.gamma.-benzyl L-glutamate) liquid crystal as studied by proton NMR under high pressure

Some aspects of high‐pressure NMR

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The conformation of the unbranched paraffin chain C22H46 in solution as studied by high pressure NMR

Cited by 6 publications

References 13 publications

High-Pressure Raman Noncoincidence Effect and Conformation of Alkyl Side Chain in Alkyl Benzoates

High-Pressure Raman Noncoincidence Effect and Conformation of Alkyl Side Chain in Alkyl Benzoates

Effect of pressure on the magnetic orientation of the poly(.gamma.-benzyl L-glutamate) liquid crystal as studied by proton NMR under high pressure

Some aspects of high‐pressure NMR

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The conformation of the unbranched paraffin chain C₂₂H₄₆ in solution as studied by high pressure NMR