Odd-even effect in free radical polymerization of optically active 2,5-bis[(4′-alkoxycarbonyl)-phenyl]styrene

The effects of the position and configuration of the stereogenic carbon atom in vinyl monomers on the optical activity of their respective polymers through radical polymerization was investigated. The monomers were prepared in moderate yields by estrification of chiral alcohols, which was preconverted to highly active acyl chloride by reaction with oxalyl chloride in the presence of trace amount of the polymer. The opposite sign of the polymer to its monomer and a large increase in chiral optical power indicate that the optical activity of polymer is not solely attributed to the configurational chirality in the side groups. The circular dichroism (CD) spectrum of the polymer exhibits one positive Cotton effect at the wavelengths less than 223 nm and two negative Cotton bands in the wavelength ranges of 223-279 and 279-343 nm.