Acetylation of alpha-chitin in ionic liquids.
Acetylation of alpha-chitin using acetic anhydride in an ionic liquid, 1-allyl-3-methylimidazolium bromide (AMIMBr), was performed. First, a mixture of chitin and AMIMBr (2% w/w) was heated at 100 degrees C for 24h for dissolution. Then, acetic anhydride (5-20 equiv) was added to the solution and the mixture was heated with stirring at desired temperatures for 24h. The product was precipitated by the addition of the reaction mixture into methanol. The IR spectrum of the product indicated the progress of acetylation. The degrees of substitution (DS), which were determined from the IR spectra, increased with increasing the amounts of acetic anhydride used for the reaction. The highest DS was 1.86, which was obtained by the reaction using 20 equiv of acetic anhydride at 100 degrees C. The product with this DS value was soluble in DMSO, and thus the structure of the product was further confirmed by (1)H NMR spectroscopy in DMSO-d(6). The DS value estimated by the integrated ratio of signals due to acetyl protons to a signal due to anomeric protons was in good agreement with that determined from the IR spectrum.
Mine
Shozaburo
S
Graduate School of Science and Engineering, Kagoshima University, 1-21-40 Korimoto, Kagoshima 890-0065, Japan.
Izawa
Hironori
H
Kaneko
Yoshiro
Y
Kadokawa
Jun-Ichi
J
D000089:Acetic Anhydrides / Q000737:chemistry; D000107:Acetylation; D000498:Allyl Compounds / Q000737:chemistry; D002686:Chitin / Q000737:chemistry*; D007093:Imidazoles / Q000737:chemistry; D052578:Ionic Liquids / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy
C544334:1-allyl-3-methylimidazolium; D000089:Acetic Anhydrides; D000498:Allyl Compounds; D007093:Imidazoles; D052578:Ionic Liquids; D002686:Chitin; C031800:acetic anhydride