INVESTIGATIONS ON THE DISSOCIATION BEHAVIOR OF HYDROLYZED ALTERNATINGCOPOLYMERS OF MALEIC-ANHYDRIDE AND ALKENES - C-13-NMR SPECTRA AND POTENTIOMETRIC TITRATIONS

The pK(a) values of the succinic acid moieties of hydrolyzed alternati ng ethene- and isobutene-maleic anhydride copolymers were determined i n D2O. The pn-dependence on the C-13 chemical shift of selected signal s was analyzed for these copolymers. Four different pK(a)s were determ ined for the copolymer with ethene due to the existence of both the er ythro- and three-configuration of the succinic acid moiety: PK01,eryth ro = 4.2, pK(01,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 pK(01) = 3.0 and pK(02) = 8.7 were observed for the hydrolyzed form. (C) 1996 John Wiley & Sons, Inc.