2.3.2.5 Fraxetin
Synonyms 7, 8-Dihydroxy-6-methoxycoumarin.
Biological Source It is the aglucon of fraxin. Fraxin is present in the seeds of Acsculus hippocastanum L. (Hippocastanaceae)-Horse Chestnut.
Preparation Fraxetin is obtained by heating fraxin with dilute sulphuric acid to affect the hydrolysis of glucoside and get the desired aglucon residue as shown here under:
Characteristic Features Fraxetin is obtained as plates from ethanol having mp 228°C. It has been observed that it turns first yellow at 150°C and subsequently brown at mp. It is soluble in 10 L of cold water, but in 300 ml of boiling water. It is somewhat more soluble in alcohol and practically insoluble in ether.
Identification Tests It forms the corresponding dimethyl ether termed as 6,7,8-trimethoxycoumarin (C12H12O5) which has a mp 104°C and bp0.2 90-100°C.
