Investigations on the dissociation behavior of hydrolyzed alternating copolymers of maleic anhydride and alkenes: 13C-NMR spectra and potentiometric titrations

The pK_a values of the succinic acid moieties of hydrolyzed alternating ethene- and isobutene-maleic anhydride copolymers were determined in D₂O. The pD-dependence on the ¹³C chemical shift of selected signals was analyzed for these copolymers. Four different pK_as were determined for the copolymer with ethene due to the existence of both the erythro- and threo-configuration of the succinic acid moiety: pK_01,erythro = 4.2, pK_0.1,threo = 4.1, pK_02,erythro = 6.1, pK_02,threo = 6.8. The isobutene-maleic anhydride copolymer contains only threo-units. Therefore, only two dissociation steps with pK₀₁ = 3.0 and pK₀₂ = 8.7 were observed for the hydrolyzed form. © 1996 John Wiley & Sons, Inc.