ALKALINE N-DEACETYLATION OF CHITIN ENHANCED BY FLASH TREATMENTS - REACTION-KINETICS AND STRUCTURE MODIFICATIONS

A new method for N-deacetylation of chitin is proposed in which a polymer almost free of N-acetyl groups is obtained by flash treatment. The reaction is carried out in 40% NaOH solution for 30-270 s at 140-190°C, using saturated steam. Flash treatment was found to proceed faster and with a higher activation energy for the deacetylation reaction (Ea = 36 kcal mol-1) compared with the traditional treatment (Ea = 11 kcal mol-1). X-Ray diffractometry, CP-MAS 13C-NMR and FTIR spectroscopy show that the flash treatment induces structure modifications; in particular, higher crystallinity indexes and specific area values are observed together with changes in the local and chain conformation. © 1990.