Cellulose with dimethyl sulfoxide-acetic anhydride

Selective oxidation of amylose at C3 has been achieved with dimethyl sulfoxide/phosphorus pentaoxide [119]. In contrast, the oxidation of unprotected cellulose with dimethyl sulfox-ide/acetic anhydride [120] or dicyclohexylcarbodiimide/dimethyl sulfoxide [121] produced a product containing modified 8-D-glucopyranosyl units - some with a carbonyl function at C2, some with a carbonyl function at C3, and some with carbonyl functions at both C2 and C3[122],... 

Cellulose dissolved in suitable solvents, however, can be acetylated in a totally homogeneous manner, and several such methods have been suggested. Treatment in dimethyl sulfoxide (DMSO) with paraformaldehyde gives a soluble methylol derivative that reacts with glacial acetic acid, acetic anhydride, or acetyl chloride to form the acetate (63). The maximum degree of substitution obtained by this method is 2.0 some oxidation also occurs. Similarly, cellulose can be acetylated in solution with dimethylacetamide—paraformaldehyde and dimethylformamide-paraformaldehyde with a potassium acetate catalyst (64) to provide an almost quantitative yield of hydroxymethylceUulose acetate. 

Influence of the amount tetra- -butylammonium fluoride (TBAF) trihydrate ou the efficieucy of the acetylation of sisal cellulose with acetic anhydride in dimethyl sulfoxide (DMSO)/TBAF (adapted from [28])... 

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