Partial hydrolysis of cellulose acetate in toluene/acetic acid/water system

Abstract

The partial hydrolysis of cellulose acetate was studied in homogeneous toluene/acetic acid/water media of different compositions using sulfuric acid as a catalyst. The presence of toluene considerably increases the hydrolysis rate. Products with a degree of substitution (DS) of about 1.70, useful for further derivatization, were obtained at 60°C with 15–34 wt.‐% toluene in the reaction medium and without addition of water during the process in shorter times than in the conventional procedure free of toluene. The kinetic behaviour of toluene‐containing systems is dependent on the composition of the reaction medium, as well as on the temperature. The reaction systems with 15 wt.‐% and 20 wt.‐% toluene, respectively, were found to obey a linear relationship of ‐ln(DS/DS0) versus time. The behaviour of the studied reaction systems is tentatively explained by an enrichment of the solvation shell in water and sulfuric acid, since the acidity function of the sulfuric acid was not influenced by the presence of toluene. The hydrolysed products obtained by the described procedure are soluble in some common organic solvents used for derivatization, such as dimethylformamide, acetic acid and dimethyl sulfoxide.

Cellulose acetate deacetylation in benzene/acetic acid/water systems

“…Besides this effect, we may also take into consideration the influence of the benzene upon the compatibility of the catalyst (sulfuric acid or its hydrates) with the solvent system containing a hydrocarbon. Our previous data, related to the partition of sulfuric acid in such solvent systems containing cellulose,4 showed that the amount of catalyst retained on cellulose increased with increasing hydrocarbon content. Therefore, this compatibility is lower in such systems compared with the reference system, free of benzene, suggesting that the concentration of the catalyst is increased in the solvation shell, which accelerates the deacetylation process.…”

“…In previous experiments, we observed that the presence of toluene in the hydrolysis media remarkably decreased the time required for obtaining soluble far‐hydrolyzed cellulose acetates, useful for further derivatization 4, 5…”

Synthesis and testing of cellulose acetate nicotinate as adsorbent for rhodamine B dye

“…Figure (a) shows the 1 H ‐ NMR spectrum of CAN and, as inset, the structural formulas of CAN together with the number of carbon atoms of cellulosic anhydroglucose units (AGU) as well as of acetyl and nicotinoyl groups. The signals corresponding to acetyl and cellulose chain were identified. The strong chemical shift signals from 1.8 to 2.2 ppm were assigned to methyl hydrogen H14 of acetyl groups.…”

“…CA with a DS value of 1.73 was prepared by using a method presented in previous papers . Pyridine, p‐toluenesulfonyl chloride, sulfuric acid, DMF, toluene, acetic acid, NA, potassium carbonate, sodium bicarbonate, and RhB were purchased from Sigma‐Aldrich (St. Louis, MO, USA).…”

“…CA with a DS value of 1.73 was obtained by hydrolysis in a homogeneous system starting from highly acetylated cellulose via a method described elsewhere . In a round‐bottom flask, a quantity of 10 g of CA with a DS value of 2.5 was added to 160‐mL acetic acid‐water (9:1 w/w) over which 0.6 g of sulfuric acid was added under stirring at room temperature.…”