N,N′-Divinylureas: Further Polymerization Studies and Spectroscopic Investigation of Structure

Abstract Homopolymerization of 1, 3-divinylimidazolid-2-one and 1, 3-divinylhexahydropyrimid-2-one produces cross-linked polymers. 1, 3-Diphenyl-1, 3-divinylurea (DPDVU) and 1, 3-dimethyl-1, 3-divinylurea (DMDVU) could not be polymerized. 1-Ethyl-3-vinylimidazolid-2-one yields a soluble linear polymer. All of the N, N′-divinylureas have a strong absorption band in the UV region of the spectrum, which is good evidence for conjugation of the electron pairs on the nitrogen atom with the π-electrons of the vinyl and carbonyl double bond. Further support for conjugation is obtained from NMR and IR spectroscopy. Such conjugation would tend to favor intermolecular propagation rather than the cyclopolymerization mechanism. The inability of DPDVU to polymerize is explained by the fact that addition of a radical to this monomer produces a resonance stabilized free radical. The failure of the intermolecular propagation reaction with DMDVU is attributed to steric hinderance. Rapid hydrolysis of the N-vinyl group in these compounds takes place in aqueous solution, yielding acetaldehyde and the corresponding urea.