2.3.2.4 Daphentin
Synonyms 7, 8-Dihydroxycoumarin;
Biological Sources It is the aglucon of daphnin. It is obtained from the seeds and fruits of Daphne mezereum L. (Thymelaeaceae)-Mezereon; and the seeds of Euphorbia lathyris L. (Euphorbiaceae)-Mole Plant, Petroleum Plant, Caper Spurge.
Preparation Daphentin is prepared conveniently from its glucoside known as daphnin i.e., 7, 8-dihydroxycoumarin 7-β-D-glucoside by treating the latter in three different ways, namely: (i) By boiling with dilute mineral acids; (ii) By enzymatic hydrolysis; and (iii) By sublimation as given below:
Characteristic Features The crystals obtained from dilute ethanol has a mp 256°C (decomposes). It undergoes sublimation on heating. It is soluble in boiling water, hot dilute alcohol and hot glacial acetic acid. It is found to be sparingly soluble in ether, CS2, chloroform, and benzene.
Identification Tests
1. An aqueous solution of daphentin gives a green colouration with FeCl3 solution, which turns red on the addition of sodium carbonate.
2. An alkaline solution of daphentin in alkali carbonate or alkali gives a yellow colour.
