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Home  >  Journal list  >  Polymer Journal  >  Vol.17  No.4 (1985)  >  pp.641-655

Polymer Journal
<<Previous article Vol.17  No.4 (1985)   pp.641 - 655 Next article>>

NMR Studies and Conformational Energy Calculations of 1,2-Dimethoxyethane and Poly(oxyethylene)

Kenzabu Tasaki1) and Akihiro Abe1)
1) Department of Polymer Chemistry, Faculty of Engineering, Tokyo Institute of Technology

ABSTRACT:  Conformational studies on 1,2-dimethoxyethane (DME), a monomer model compound of poly(oxyethylene), have been carried out by using NMR technique. The observed temperature dependence of the vicinal coupling constants was analyzed on the basis of the rotational isomeric state scheme. For the C–C bond, the 13CH satellite side bands provide the desired information. Conformational energy Eσ, representing the energy of the gauche state expressed relative to the trans, was found to vary in a range −0.5 to −1.2 kcal mol−1, depending on the solvent system. Values of JT and JG for the vicinal 1H–1H coupling were determined concomitantly: JT=11.4±0.3 and JG=2.3±0.1 Hz. For the rotation about the C–O bond, the vicinal 13C–1H coupling constant associated with the terminal methyl group was studied. Adoption of JG=1.3 Hz leads to an estimate of Eρ=0.8 to 1.1 kcal mol−1 for the energy difference between the gauche and trans states. In these treatments, the neighbor-dependent character of the bond rotation along the chain was rigorously taken into account. The values of Eσ and Eρ derived for the polymer are comparable with those of DME. The results are compared with those reported previously by Viti et al. and Mastuzaki et al.


Keyword:
1,2-Dimethoxyethane/ Poly(oxyethylene)/ 13CH Satellite NMR/ 13C NMR/ Vicinal Coupling Constant/ Potential Energy Calculation/ Conformational Energy

Published online: March 03, 2006
© Copyright, 2006 by The Society of Polymer Science, Japan

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