Tohru Doiuchi

Cyclocopolymerization of d-limonene with maleic anhydride

Abstract d -Limonene (Lim), a nonconjugated 1,5-diene, was copolymerized with maleic anhydride (MAn) in tetrahydrofuran with α,α′-azobisisobutyronitrile as initiator. The composition, spectral analyses, and other physical properties of the resulting copolymer and its hydrolysed product suggest that Lim readily undergoes an inter-intramolecular cyclocopolymerization with MAn, leading to a 1:2 alternating copolymer. The findings and the proposed cyclocopolymerization mechanism are consistent with participation of a charge-transfer complex of the comonomers in the propagation step. The copolymers are optically active and their CD spectra are characterized by dichroic bands attributable to electronic transitions of carbonyl or carboxylic chromophores.

Stereoelective radical copolymerization of (RS)-α-methylbenzyl vinyl ether with (S)-(−)- or (R)-(+)-N-(α-methylbenzyl) maleimide

Abstract Racemic α-methylbenzyl vinyl ether was copolymerized with optically active (S)-(-)- or (R)-(+)-N-(α-methylbenzyl)maleimide using 2,2′-azobisisobutyronitrile in order to examine the possibility of stereoelective radical polymerization of vinyl-type racemic monomers. The resulting copolymers were found to have almost alternating sequences of the two kinds of monomeric units. The non-polymerized α-methylbenzyl vinyl ether, recovered from the copolymerization system, showed an optical activity of opposite sign to the optically active comonomer used, indicating clearly that the co-polymerization process is stereoelective. It was confirmed that α-methylbenzyl vinyl ether preferentially incorporated in the copolymer has the same absolute configuration as the optically active N-substituted maleimide.