| Summary: | Immobilization of humic acid (HA) onto chitosan using tosylation method with 1,4-butanediolas a spacer arm has been evaluated. Chitosan was phthaloylated selectively using phthalic anhydride in dimethylformamide as solvent with addition of 5% water (v/v) as cosolvent prior to be tosylated. N-phthaloyl-chitosan and HA were tosylated using tosyl chloride in excess and triethylamineas catalyst at temperature< 10 °C for 12h. The 6-0-tosyl- N-phthaloyl-chitosan was reacted with 1,4-butanediolin order to obtain a spacer arm attached chitosan. The 6-0- butanol-N-phthaloyl-chitosanwas activatedby reacting with tosyl chloride. For evaluation on immobilizationof HA on
chitosan with and without spacer arm, 6-0-tosylbutane-N-phthaloyl-chitosanwas reacted with HA and the 6-0-tosyl-
N-phthaloyl-chitosanwas reacted with HA. The HA immobilized onto chitosan was characterizedby XRD and FTIR spectrophotometricmethod. The result showed that HA can be immobilized covalently onto chitosan after attaching 1,4-butanediolas spacer arm onto 6-0-tosyl-N-phthaloyl-chitosanand activating the product with tosyl chloride, but HA cannot be reacted directly onto 6-0-tosyl-N-phthaloyl-chitosan.
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