Carbon-13 NMR Spectra of Branched Paraffins, Alicyclic Compounds and Alkylbenzenes, and Carbon-13 NMR Analysis of Paraffin Oils

満, 山崎; 次夫, 武内; 和弘, 松下

doi:10.1246/nikkashi1898.74.4_656

Cited by 5 publications

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“…15 The solvent peaks are greatly attenuated and pratically negligible compared to the polymer peaks, because the repetition times of the 90° pulses are much less than the spin-lattice relaxation times of the carbons in the solvent and because of splitting due to 13 C-2 D spin coupling.…”

Section: Methodsmentioning

confidence: 99%

A Carbon-13 NMR Study of Molecular Motion of Polystyrene in Solution

Inoue

Konno

1976

Polym J

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ABSTRACT:The molecular motion of polystyrene in solution has been investigated quantitatively using carbon-13 NMR. It is concluded that the motion can be characterized by three contributions, namely, segmental motion and two kinds of internal rotation of the phenyl ring, and that the phenyl ring is rotating more freely above 50°C. Free rotation of the phenyl ring is hindered by a energy barrier, which is probably due to a steric hindrance between the hydrogens in the phenyl ring and the methine hydrogen in the adjacent monomer unit. This model is consistent with the fact that a transition of polystyrene at about 50°C occurs both in solutions and in bulk. KEY WORDSPolystyrene / 13 C NMR / Molecular Motion / Internal Rotation / Transition / Spin-Lattice Relaxation / It has been generally accepted that solutions of isotactic and atactic polystyrene show an anomalous temperature dependence in solution properties at about 50 and S0°c. 1 -5 A transition was observed at about 80°C for isotactic and atactic polystyrene in several solvents in the temperature dependence of the second virial coefficient, in the mean radius of gyration, and in other properties. This transition is firstorder, 6-8 and Reiss 6 • 7 has proposed that it arises from the transition between a 31 helix and a random coil in the isotactic sequences of both polymers.On the other hand a transition at about 50°C in isotactic and atactic polystyrene both in solution and in bulk has been reported. 1 As 50°C is well below the glass-transition temperature (ca. l05°C), it was thought that the major molecular process can not be a conformational change but an intramolecular change of more local molecular motions. It was proposed that rotation of the phenyl ring may be hindered by the a and /3 main-chain hydrogens, and that the transition at about 50°C may be due to a sudden change in the mobility of the phenyl ring. 9 However, the molecular motion has not been heretofore studied quantitatively; we have used 13 C NMR to elucidate the molecular process occurring in this transition.Although physical properties of polymer solutions have been studied with proton NMR, data are often rather complex to analyze because of a narrow range of chemical shifts (ca. IO ppm) and of splitting of peaks due to spin-spin coupling. Proton-decoupled natural abundance 13 C NMR spectra are easier to analyze because of a wide range of chemical shifts (ca. 250 ppm) and the absence of complex spin-spin coupling. Partially relaxed Fourier transformed (PRFT) spectra permit measurement of the 13 C spinlattice relaxation times for all resolved peaks of complex molecules. It is of interest to measure the 13 C spin-lattice relaxation times of individual carbons in molecules, as the molecular motion of individual groups can be estimated quantitatively. Proton magnetic relaxation times .are difficult to analyze quantitatively in terms of molecular motion because of the difficulty of separating intramolecular and intermolecular contributions. The latter contribution to 13 C spin-lattice relaxatio...

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Section: Methodsmentioning

confidence: 99%

A Carbon-13 NMR Study of Molecular Motion of Polystyrene in Solution

Inoue

Konno

1976

Polym J

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Quantitative analysis by nuclear magnetic resonance with fourier transform II¹³C resonance

Thiault¹,

Mersseman²

1976

Org. Magn. Reson.

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Abstract-Quantitative analyses have been carried out by 13C NMR spectroscopy using Fourier transformation. The Overhauser effect, due to the broad band decoupling of protons, has been suppressed using the two existing methods (gated decoupling and paramagnetic species), and results from each are compared. Both require a calibration curve, and the second method, when applied to aromatic substances, needs the ratio between the sample to be analysed and the paramagnetic species to be less than a certain value. Experiments have been made with pure products and blends of pure products containing both saturated and aromatic carbons. The precision of the results is given.

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¹³C NMR chemical shifts of thiols, sulfinic acids, sulfinyl chlorides, sulfonic acids and sulfonic anhydrides

Freeman

Angeletakis

1983

Org. Magn. Reson.

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Carbon-13 NMR Spectra of Branched Paraffins, Alicyclic Compounds and Alkylbenzenes, and Carbon-13 NMR Analysis of Paraffin Oils

Cited by 5 publications

References 0 publications

A Carbon-13 NMR Study of Molecular Motion of Polystyrene in Solution

A Carbon-13 NMR Study of Molecular Motion of Polystyrene in Solution

Quantitative analysis by nuclear magnetic resonance with fourier transform II¹³C resonance

¹³C NMR chemical shifts of thiols, sulfinic acids, sulfinyl chlorides, sulfonic acids and sulfonic anhydrides

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Carbon-13 NMR Spectra of Branched Paraffins, Alicyclic Compounds and Alkylbenzenes, and Carbon-13 NMR Analysis of Paraffin Oils

Cited by 5 publications

References 0 publications

A Carbon-13 NMR Study of Molecular Motion of Polystyrene in Solution

A Carbon-13 NMR Study of Molecular Motion of Polystyrene in Solution

Quantitative analysis by nuclear magnetic resonance with fourier transform II13C resonance

13C NMR chemical shifts of thiols, sulfinic acids, sulfinyl chlorides, sulfonic acids and sulfonic anhydrides

Contact Info

Product

Resources

About

Quantitative analysis by nuclear magnetic resonance with fourier transform II¹³C resonance

¹³C NMR chemical shifts of thiols, sulfinic acids, sulfinyl chlorides, sulfonic acids and sulfonic anhydrides