Synthesis and characterization of N-aryl chitosan derivatives.
Selective N-arylation of chitosan was performed via a Schiff bases formed by the reaction between the 2-amino group of glucosamine residue of chitosan with an aromatic aldehyde under acidic condition followed by reduction of the Schiff base intermediate with sodium cyanoborohydride (Borch reduction). Aromatic aldehydes bearing either an electron donating or electron withdrawing substituent were used. The chemical structures and thermal properties of the N-aryl chitosans were characterized by FT-IR, (1)H NMR, (13)C NMR, TGA, and DSC. The extent of N-substitution (ES) was influenced by the molar ratio of the aldehyde to the glucosamine residue of chitosan, the reaction time and the substituent on the aromatic ring. Lower ESs resulted from N-arylation using an aldehyde with an electron donating substituent. A linear relationship between the targeted ES and the ES obtained was observed when aldehydes bearing electron withdrawing substituents were employed.
Sajomsang
Warayuth
W
Green Chemistry Research Laboratory, Department of Chemistry, Faculty of Science, Chulalongkorn University, Pathumwan, Bangkok 10330, Thailand.
Tantayanon
Supawan
S
Tangpasuthadol
Varawut
V
Thatte
Mrunal
M
Daly
William H
WH
D000447:Aldehydes / Q000737:chemistry; D001894:Borohydrides / Q000737:chemistry; D048271:Chitosan / Q000138:chemical synthesis* / Q000737:chemistry*; D005944:Glucosamine / Q000737:chemistry; D009682:Magnetic Resonance Spectroscopy; D015394:Molecular Structure; D012545:Schiff Bases / Q000737:chemistry; D017550:Spectroscopy, Fourier Transform Infrared
D000447:Aldehydes; D001894:Borohydrides; D012545:Schiff Bases; D048271:Chitosan; C009282:sodium cyanoborohydride; D005944:Glucosamine