Synthesis Of 6, 7-dihydroxycoumarin

Qinpi is from the branch bark of five Fraxinus plants. It is a traditional Chinesemedicine, written by Ben Cao through the ages, can cure diarrhea, fever and relieve painand so on.As the critical effective composition, the interest in the esculetin is a result of thediscovery of its pharmaceutical potential, such as (1) treatment on diseases of intestine. Forinstance, small intestine diarrhoea; a intestine ulcer; helc-enteritis.(2) cure on chronicconjuction.(3) the inhibition of osteoarthritis, antibacterial, and anti-oxidation.(4)participation directly in interaction of bovine serum albumin-metal lons. Besides, esculetinhas long been used in traditional medicine, for example, in the treatment of dysuresia,suppression on nervous centralis, anti-tumor, suppression cancercell growth.In this dissertation, the synthesis ways of esculetin were studied, the way Two isdesigned, and the reaction mechanism was discussed. Effects of various conditions to thereaction were optimized by unifactor and multifactor orthogonal experiment. The optimalreaction conditions are that the amounts of p-Benzoquione: Acetyl acetate: concentratedsulfuric acid=1: 3: 0.15(mole ratio), at 3 h and 45℃, the yield reached 89.2％; and thereaction temperature is about 120℃and time is 2 h, the volume of concentrated sulfuricacid is 10mL, the amount of 1, 2,4—benzenetriol is 5 g, the amount of malic acid is about5.6 g, the selectivity of esculetin could reach about 80％.The structure of the synthetic products were characterized by Differential ScanningCalorimetry(DSC), Infrared Spectroscopy(IR), Mass Spectra(MS)and ~1H NuclearMagnetic Resonance(NMR). The results proved: the structures and performance indexes ofthe products conformed to the design requirement, and the yield of every reation was morethan 70％, this can prognosticate the synthesis design of using the original rawmaterical(benzoquinone), synthesize esculetin was novel, practical and effective.