The Studied On The Ultrasonically Assisted Extraction Of Hesperidin From The Orange Peel And The Synthesis Of Flavonoids From Hesperidin

Flavonoids are a kind of natural organic compounds with potential physiological activities and effective components of Chinese Herbs, which have attracted more and more research interest and exist in nature extensively. Hesperidin belongs to Flavanone glycosides. This dissertation is concerned with the extraction, separation, idendification, and synthesis of the flavonoids, the main contents of the research are as follows.In the first part, the new technics of extraction and isolation of Hesperidin from the orange peel is exploited under ultrasonic feild. The chemical investigation on the orange peel has led to the isolation of Hesperidin in higher yield and shorter reaction time. The optimum extraction conditions are determined by orthogonal design method as follows: extraction temperature is 25°C, extraction time is 40 minutes, the rate of saturated calcium hydroxide solution to orange peel in weight is 4:1, and the frequence of ultrasonic reactor is 25KHz. The average extraction rate of Herperidin and relative standard deviation(RSD) are 2.07% and 0.91%(n=3) respectively.In the second part, the successful synthesis of Flavonoids compounds such as hesperetin, persicogenin, diosmetin and 7-0-isopentenyl Hesperietin in 65%-96% yield respectively by using Hesperidin as the starting materials is reported, these Flavonoids compounds structures have been determined by means of MS, IR and ¹HNMR spectroscopic methods, The 7-O -isopentenyl Hesperietin is a new compound and was synthesized for the first time. Meanwhile, the reaction condition of the synthesis from Hesperidin to Flavonoid as above is studied, since the reaction active is different for C₇-OH, C₅-OH and C₃-OH groups in Flavonoid structure, the regioselectivity is in agreement with the preferential dissociation of C₇-OH in base, the amount of K₂CO₃:Hespertin should be 1:1, the reaction temperature should be controlled 50°C. The experiment repeatedly provides the synthesis route a practical technical condition.