Determination of Sulphate Acid Ester in Unstabilized Cellulose Nitrate by the Hydrolysis Method

Abstract

The method of deter~uining sulphate acid ester in unstabilized cellulose nitrates by hydrolysis in acetone/water solution was evaluated. The precision of duplicate determinations for cotton and wood cellulose nitrates containing about 100% sulphate ester was -0.1 to +5.9% and +0.4 to +9.2%, respectively. With cellulose nitrates containing 69-43% and 69-47% sulphate ester, i t was +1.8 to +13.4% and +0.4 t o +21.0%. The sulphate acid ester content of both unstabilized cotton and wood cellulose nitrates increased with decreasing nitrogen content.

Hydrolysis of Sulphate Acid Ester in Unstabilized Cellulose Nitrates

“…Samples were then set aside for moisture, nitrogen, and sulphate determinations (3). The per cent sulphate acid ester contents of the cellulose nitrates were determined by the hydrolysis method (6).…”

“…The initial acidity of moist samples of cellulose nitrate in which there was no hydrolysis was determined by titration in goy0 acetone/water solution, using the method recently described (6).…”

Slurry Titrations of Unstabilized Cellulose Nitrate

“…The proportion of the slurry titer value due to sulphate acid ester can be calculated using the sulphate acid ester content obtained by the hydrolysis method (6). The portion of the slurry titer due to sulphate acid ester can be converted to sulphate, expressed as yo HzSO.r, by using 98 as the equivalent weight of the ester.…”

“…An example serves to illustrate the calculations involved. For instance, a cotton cellulose nitrate was shown to contain 96y0 sulphate acicl ester by the hydrolysis method (6). The slurry titer expressed as rnl./g.…”

“…Recently, the hydrolysis method for determining the sulphate acid ester was carefully studied (6). T h e object of the present work was to evaluate the slurry titration of unstabilized cellulose nitrate in water and t o investigate the possibility of using this type of titration for determining the sulphate acid ester coi~tent of unstabilized cellulose nitrate.…”