Preparation of chitin butyrate by using phosphoryl mixed anhydride system

Acylation of chitin with butyric acid was performed in the presence of trifluoroacetic anhydride/phosphoric acid mediated system. The products were characterized by ¹H NMR and FT-IR spectroscopy and their solubility was tested in different organic solvents. Inclusion of butyric acid moieties into the parent molecule was confirmed from the ¹H NMR and FT-IR spectra. FT-IR analysis revealed that the degree of acid substitution (DS) of the products was in a range of 1.9–2.38, which increased with increasing the amounts of butyric acid added to the reaction system. Degree of N-deacetylation (DD) of the products, as determined by ¹H NMR was between 54.2% and 65.6%. The products with DS >2.0 were soluble in dimethyl sulfoxide, N,N-dimethylformamide, tetrahydrofuran, methanol, acetone, chloroform, and acetic acid.