Analysis of the liquid fraction after esterification of sawdust with octanoyl chloride — Production of esterified hemicelluloses

Solvent-free esterification of wood with octanoyl chloride produced an esterified material with a weight increase of 87% and an ester content of 60%. However, a fraction of sawdust (22% of the esterified wood) was solubilized during this esterification. Chemical analyses showed that it contained essentially esterified and hydrolyzed hemicelluloses with small amount of esterified cellulose. The reactivities of oakwood sawdust and wheatbran hemicelluloses were compared under different reaction conditions. Pure hemicelluloses were more reactive and more readily hydrolyzed (without using solvent) than sawdust, to give esterified oligomers and polymers with a high degree of substitution, and which were solubilized (48% of the esterified hemicelluloses) in the reaction medium. The use of pyridine as a toxic solvent limited the acid hydrolysis of the polysaccharides chains and therefore their solubilization