CELLULOSE DERIVATIVES WITH LOW DS .2. ANALYSIS OF ALKANOATES

The determination of the degree of substitution (DS) of cellulose alka noates representing a wide range of ester types (acetate (C-2), to ste arate (C-18), with a DS of 0 to 3) was performed by H-1-NMR spectrosco py and aminolysis/gas chromatography. Poor solubility combined with co mplex substituent signals preclude proton NMR spectroscopy as a method of analysis when the DS of alkanoates falls below one. This is true f or all ester-derivative types, especially for the derivatives with bul ky substituent groups. By contrast, the aminolysis/gas chromatography method is independent of both solubility and DS, and thus represents t he method of choice for cellulose esters which have low degrees of sub stitution and bulky substituent groups..