Maleic anhydride, asymmetric copolymerization

A further example of radical asymmetric polymerization is the copolymerization between maleic anhydride and styrene (357-359). The reaction takes place in an emulsion in the presence of lecithin and the asymmetric induction... 

A special case of asymmetric enantiomer-differentiating polymerization is the isoselective copolymerization of optically active 3-methyl-1-pentene with racemic 3,7-dimethyl-1-octene by TiCl4 and diisobutylzinc [Ciardelli et al., 1969]. The copolymer is optically active with respect to both comonomer units as the incorporated optically active 3-methyl-l-pentene directs the preferential entry of only one enantiomer of the racemic monomer. The directing effect of a chiral center in one monomer unit on the second monomer, referred to as asymmetric induction, is also observed in radical and ionic copolymerizations. The radical copolymerization of optically active a-methylbenzyl methacrylate with maleic anhydride yields a copolymer that is optically active even after hydrolytic cleavage of the optically active a-methylbenzyl group from the polymer [Kurokawa and Minoura, 1979]. Similar results were obtained in the copolymerizations of mono- and di-/-menthyl fumarate and (—)-3-(P-styryloxy)menthane with styrene [Kurokawa et al., 1982],... 

Another type of matrix effect on the properties of the product was described by Doiuchi and Minoura who copolymerized indene with maleic anhydride in the presence of lecithine as a chiral surface active agent [39], The rate of radical copolymerization in benzene is reduced in the presence of lecithine. An optically active copolymer is formed (the asymmetric carbon is marked by the asterisk, )... 

As anticipated, upon reaction of this polymeric ester under hydrogen with phosphonium iodide, the poly(methacrylic acid) which had formed in an 84% yield showed no optical activity. When the same ester was copolymerized with three molar equivalents of maleic anhydride, the resulting ester-anhydride copolymer had an optical rotation of [hydrogen with phosphonium iodide, the resulting polymethacrylic acid had an optical rotation of = +23° (Note the reversal of the optical rotation in this case.) This appears to have been the first demonstration of a case of asymmetric induction during vinyl polymerization. 

Maleic anhydride has been copolymerized in benzene solution with seven different optically active alkyl vinyl ethers, having an asymmetric carbon atom at the a, (3, y, or S position of the alkyl residue (Table Chemical... 

Partially stereoregular copolymers have been obtained by asymmetric polymer synthesis using maleic anhydride as one comonomer and optically active a-methylbenzyl methacrylate (216) or a-methylbenzyl vinyl ether (217) as the other comonomer. These copolymers were optically active even after removal of their a-methylbenzyl groups (Scheme 25). Analogous results have been obtained by Minoura s group (218, 219) on copolymerizing optically active a,3-disubstituted olefins with achiral vinyl monomers. 

Nishihara et al [11] have also reported that an asymmetric structure is induced into the polymer main chain by copolymerization of methacryl-1-valine methyl ether and methacryl-1-proline methyl ether with maleic anhydride. 

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