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ABSTRACT

Carboxymethyl (CM-) kefiran was prepared with monochloroacetic acid in isopropyl alcohol at 30, 40 and 50°C for 4 and 24 hr. Resulting CM-kefiran varied in degree of substitution (0.73-0.89), molecular weight (5.0-7.0 × 105) and viscosity (4.5-14.5 cP in 0.5% aqueous solution) depending on the conditions. Carboxymethylation resulted in a maximum fourteenfold increase in viscosity. 13C-NMR spectra of CM-kefiran indicated C-6 of native kefiran was preferentially substituted with CM-groups.