Unusually Facile Cyclopolymerization of a New Allyl Ether Substituted Acrylate and Confirmation of Repeat Unit Structure by Inadequate NMR
Polymers and High Performance Materials
We have synthesized and polymerized ethyl alpha-[(allyloxy)methyl]acrylate and allyl alpha-(hydroxymethyl)acrylate, two diene monomers being evaluated as possible optical materials. The allyl ether showed a significant difference in polymerization behavior in comparison to the allyl ester and was found to undergo virtually complete cyclopolymerization in solution and in bulk. Ring size could not be determined directly by examination of the C-13 solution spectrum in the absence of suitable model compounds. The two-dimensional INADEQUATE NMR method (Incredible Natural Abundance DoublE QUAntum Transfer Experiment) was then used to determine the ring size generated in the new cyclopolymer. C-13 solution NMR spectral characterization gives well-defined chemical shift differences for cis and trans isomers, which can be explained by gamma-gauche shielding for carbons in or next to the polymer backbone. The methylenes connected to the quaternary carbons show a gamma-gauche effect of 6.8 ppm, a value which is at the high end of the gamma-gauche range. Two-dimensional INADEQUATE analysis conclusively confirms monomer cyclization exclusively to five-membered rings with a ratio of trans to cis ring configurations in the polymer backbone of approximately 2.2.
Thompson, R. D.,
Jarrett, W. L.,
Mathias, L. J.
(1992). Unusually Facile Cyclopolymerization of a New Allyl Ether Substituted Acrylate and Confirmation of Repeat Unit Structure by Inadequate NMR. Macromolecules, 25(24), 6455-6459.
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