Preparation and Structural Characterization of Galactans Synthesized by Phosphoric Acid Catalyzation under Microwave Irradiation

Abstract:

Galactans synthesized by phosphoric acid catalysis and microwave irradiation were studied for their chemical structures and regio- and stereo-selectivities during the polymerization. A series of analyses including high-performance gel-permeation chromatography，infrared spectroscopy，methylation analysis and NMR spectroscopies（1H，13C，1H-1H COSY，TOCSY，HSQC，HMBC） were used. Results showed that the degree of galactosyl polymerization was 16 and the -galactopyranosyl residues were dominant mainly with →4）-?琢-D-Galp（1→ and →2，4）-?琢-D-Galp（1→ fragments. Structural analyses further indicated that the activities of hydroxyls in galactose were different and the 4-OH exhibited the highest potency.