Study On Preparation, Antioxidant And Fungicidal Activity Of Chitooligosaccharide Derivatives By Microwave Irradiation

Microwave irradiation can provide chemical processes with special attributes sucn as enhanced reaction rates,higher yields,greater selectivity,the ease of manipulation and energy conservation.In this dissertation,a study of preparation of different molecular chitooligosaccharide under microwave irradiation was made.Several new chitooligosaccharide-base derivatives were synthesized via Sulfonation, Carboxymethylation,Schiff Base formation,and metal Coordination with chitooligosaccharide.Studies on antioxidant activity and antimicrobial activity of these derivatives,which can provide theory base for further application of chitooligosaccharide and its derivatives.Studies on microwave controllability degradation reaction and preparation different molecular chitooligosaccharide.The effects of various factors:reaction solution,oxidant/Chitosan ratio,microwave irradiation power and time on the degradation reaction were investigated in this paper.The results showed that chitosans with 3-100 thousand molecular weight were prepared in 1-10 minutes by microwave irradiation under the different reaction conditions.At the same time the yield was higher and repetition was well.The effect of inorganic salts such as sodium chloride on the hydrolysis of chitosan in a microwave field was investigated.The addition of some inorganic salts was shown to ffectively accelerate the degradation of chitosan under microwave irradiation by changing the reaction time and/or the radiation power.The carboxymethyl chitooligosaccharide has been prepared under microwave irradiation condition.Furthermore,the complexes of chitooligosaccharide with metal and the complexes of carboxymethyl chitooligosaccharide with metal have been synthesized by metal solution reacted with chitooligosaccharide or carboxymethyl chitooligosaccharide under microwave irradiation.The configurations of these derivatives were analyzed by UV and IR spectra.For the first time,chitosan and its complexes with copper(â…¡)or zinc(â…¡)were sulfation modified by using microwave irradiation.The metal complexes with sulfation chitosan have been synthesized.All were soluble inwater and the SO₄^2-content was over 30%.Five compounds were synthesized under microwave irradiation by the reaction of chitooligosaccharide with salicylaldehyde,and the configurations of them Mere analyzed.Based on the results of the fungicidal activity and antioxidant activity of the above four kinds of derivatives,we found these derivatives had excellent ability for scavenging the superoxide anion radical and hydroxyl radical and had also inhibition effects on the growth of crop pathogenic fungi(Valsa mali).It was proved that the activity group and metal ion can advance biology activity of these derivatives. It was estabished the foundations for research and application of chitooligosaccharide and its derivatives for the future.