ONE-STEP INTRODUCTION OF AMINE AND AMMONIUM GROUPS AND CROSS-LINKING OF POLYGALACTURONIC ACID

Polygalacturonic acid (PGA) was cross linked with epichlorohydrin (E), E-NH4OH and also with E-NH4OH in the presence of 3-chloro-2-hydroxypr opyl-trimethylammonium chloride (CHMAC). The reactions were optimized with the goal being to obtain the maximal yield and nitrogen content o f insoluble residue (IR) or water-soluble fraction (WSF). Also the amo unt of nitrogen incorporated into IR or WSF from NH4OH and/or CHMAC us ed was considered for evaluation of the optimal conditions. In the abs ence of E and NH4OH, bad yields of quaternized PGA WSP were obtained, indicating the degradation of PGA in the absence of a cross linking ag ent. The presence of functional groups was confirmed by C-13-solid sta te NMP, in IR, as well as by NMR in solution for WSF. The linkage of c ross linked PGA to functional groups, or the degree of cross linking, could not be estimated from the NMR results. This we believe is becaus e the rigidity of the cross linked matrix which causes the absence of PGA signals in the solid-state NMR spectrum. (C) 1997 Elsevier Science Ltd.