High resolution 13C-NMR spectroscopy of sodium carboxy methyl cellulose

Results of NMR studies on intact sodium carboxy methyl cellulose (SCMC) are presented. Similar studies in the literature are all on partially depolymerized SCMC. The degree of substitution and the relative distribution of substituents at OH‐2, OH‐3, and OH‐6 of anhydro D‐glucose residue in intact SCMC were determined by high resolution 13C‐NMR spectroscopy (125 MHz). It is observed that the degree of substitution at OH‐6 is almost equal to that at OH‐3. In two SCMC samples, which are widely different in molecular weight and degree of substitution (ds), the relative reactivity order of the hydroxyl groups was found to be OH‐2 > OH‐6 ≃ OH‐3. The NMR assignments were based on calculated shifts of carbons of anhydroglucose moiety in an oligosaccharide due to substitution.