Regenerated chitin from phosphoric acid solutions

Concentrated phosphoric acid at a minimum concentration of 75% readily dissolves a-chitin at room temperature. A maximum concentration of 3% (w/v) can be obtained. The initially high viscosity of these solutions decreases quickly during the first 12h. After one week in phosphoric acid, chitin yields mainly a sugar phosphate. Under the same experimental conditions, N-acetyl-D-glucosamine, the monomer of chitin, has been shown to be esterified at its anomeric position by a phosphate group. During the first hours in a phosphoric acid solution, regenerated chitins are not modified chemically although their molecular weights are reduced. Concentrated phosphoric acid is shown to be useful solvent for the preparations of regenerated chitins having an average DP from 1000 to 100, (C) 1997 Elsevier Science Ltd.