Synthesis and NMR structural analysis of 0-succinyl derivative of low-molecular-weight κ-carrageenan

Low-molecular-weight (LMW) kappa-carrageenan was achieved through mild hydrochloric acid hydrolysis of kappa-carrageenan. The acylation of LMW K-carrageenan was performed by use of tetrabutylammonium (TBA) salt of the anionic polysaccharide fragments, succinic anhydride, 4-dimethylaminopyridine and tributylamine under homogeneous conditions in N,N-dimethylformamide at 80 degrees C. Investigation of FT-IR spectrum of the succinylated LMW kappa-carrageenan showed that a monoester derivative with succinyl group was formed when LMW kappa-carrageenan reacted with succinic anhydride. The H-1 and C-13 NMR spectroscopy has been used to characterize the fine structure of O-succinyl derivative of the LMW kappa-carrageenan. The C-13 and H-1 NMR chemical shifts of disaccharide unit of O-succinyl LMW kappa-carrageenan have been fully assigned using 2D NMR spectroscopic techniques. (C) 2005 Elsevier Ltd. All fights reserved.