Preparation of ion-exchangers by cross-linking of starch or polygalacturonic acid with 1,3-bis(3-chloro-2-hydroxypropyl)imidazohum hydrogen sulphate

The reaction conditions for cross-linking of starch (S) or polygalacturonic acid (PGA) with 1,3-bis(3-chloro-2-hydroxypropyl)imidazolium hydrogen sulp hate (BCHIHS) in the presence of NaOH and water were studied in terms of th e molar ratio of the reaction components, the yields of water-insoluble pro duct, the nitrogen content and the BCHIHS conversion. The optimum for S-der ivatives was at the molar ratio of S/BCHIHS/NaOH/H2O = 0.01:0.02:0.04:0.333 with 348% yield on the amount of used S, 7.71% nitrogen content and 78% co nversion of BCHIHS. Analogically on PGA the optimum was at PGA/BCHIHS/NaOH/ H2O = 0.005:0.005:0.1:0.2 with 125% yield, 7.99% nitrogen content and 63% c onversion. The linkage of dihydroxypropylimidazolum (DHPI) groups was confi rmed by NMR in solution on water-soluble products as well as by C-13 solid- state NMR and FTIR on insoluble products. Under the used conditions much mo re NaOH is consumed on PGA while the yields of water-insoluble materials ar e lower than on S. The calculated T-1 rho(H) relaxation times gave similar values obtained previously on different polysaccharides cross-linked with d ifferent cross-linkers. The elemental composition of samples in different c ycles confirmed the ionic interaction between the quaternary ammonium group and the PGA carboxyls. (C) 2002 Elsevier Science Ltd. All rights reserved.