Solvent-free fatty acylation of cellulose and lignocellulosic wastes. Part 2: reactions with fatty acids

Abstract : The mixed acylation of cellulose with fatty acids and acetic anhydride was accomplished in an excess of fatty acid, thus avoiding the addition of a toxic solvent. The experimental design enabled the parameters of a model reaction with octanoic acid to be optimized. The products contained both acetyl and octanoyl acyl groups in a 2.4/1 ratio and the maximum degree of substitution (DS) was 2.2. The use of fatty acids higher than C8 resulted in a decrease of the DS. The model reaction was applied to the esterification of four lignocellulosic wastes (LW). Their reactivity was comparable to that of cellulose when no pretreatment was used. A solvent-exchange pretreatment improved the acylation of LW by about 60%, whereas that of cellulose was increased by more than 400%. The hydrophobic character of the esterified products was confirmed.