Optically active poly(meth)acrylamides were synthesized by the stereospecific radical polymerization of (meth)acrylamides, such as (S)-N-(2-hydroxy-1-phenylethyl)methacrylamide ((S)-HPEMA), (S)-N-(1-hydroxy-3-phenylpropyl)methacrylamide ((S)-NPMA), (R)-N-(1-phenylethyl) methacrylamide ((R)-PEMA) and (S)-N-(2-hydroxy-1-phenylethyl)acrylamide ((S)-HPEA), in the absence and presence of Lewis acids, namely, rare earth metal trifluoromethanesulfonates. The effect of Lewis acids on the radical polymerization of (meth)acrylamides was investigated. In the presence of a catalytic amount of the Lewis acid, the isotactic specificity of the polymers remarkably increased when the radical polymerization proceeded in methanol and n-butanol. However, the isotactic selectivity disappeared when the radical polymerization proceeded in DMSO. The interaction between the Lewis acid and the monomers was investigated by 1H NMR. It was found that the monomers strongly interacted with the Lewis acid in methanol-d4, which included the coordination of the amide group to the rare earth metal ion and the hydrogen bond between the hydroxyl group of the monomers and the trifluoromethanesulfonate ion of the Lewis acid. The plausible mechanism of stereocontrol in the radical polymerization of (meth)acrylamides was analyzed based on the Lewis acid-monomer interaction.

Stereospecific radical polymerization of optically active (meth)acrylamide: Study on the mechanism of stereocontrol

246th National Meeting (2013)

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