Influence of some reactional parameters on the substitution degree of biopolymeric Schiff bases prepared from chitosan and salicylaldehyde

Some reactional parameters as mol ratio (salicylaldehyde:free amino groups), reaction time and temperature were investigated in order to improve the substitution degree (DS) in the preparation of biopolymeric Schiff bases from chitosan. In this case, the reaction of chitosan and salicylaldehyde was used as a probe system in order to produce the Schiff base. The use of 50% (mol/mol) salicylaldehyde excess, reaction time of 18 h and temperature of 55 °C permitted to obtain a DS of 60% without evidences of hydrolysis of the biopolymeric matrix or changes in its acetylation degree.