ANALYSIS OF THE CARBON-13 N.M.R. SPECTRUM OF HYDROLYZED O-(CARBOXYMETHYL)CELLULOSE: MONOMER COMPOSITION AND SUBSTITUTION PATTERNS

Article abstract of DOI:10.1016/0008-6215(83)88129-4

The effects of O-carboxymethylation at each of positions 2, 3, and 6 on the ¹³C chemical shifts of glucose have been used to assign first the 13C-n.m.r. spectra of 2,3- 2,6- and 3,6-di-O-(carboxymethyl)glucose and 2,3,6-tri-O-(carboxymethyl)glucose and then the spectrum of hydrolyzed (O-carboxymethyl)cellulose (CMC).Quantitative analysis of the latter spectrum yields the composition of CMC in terms of the mole fractions of the eight component monomeric residues.The results on the monosaccharide composition for a series of samples having degrees of substitution in the range 0.55-2.17 are described well by Spurlin's statistical kinetic model for the arrangement of substituents (substitution pattern) in cellulose derivatives.The model assumes that the substitution pattern is governed by relative rate-constants for reaction of the three hydroxyl groups in the glucose residue.The values of the constants determined in this work are k₂:k₃:k₆ = 2.14:1.00:1.58.