2.2.4 Populin
Synonyms Populoside; Salicin benzoate.
Biological Source It occurs in the bark leaves of Populus tremula L., P. nigra L., P. nigral. L. var italica Duroi, P. canadensis Moench., P. grandidentate Michx., and P. tremuloides Miehx., belonging to the family Salicaceae . It is perhaps also found in Salix helix, Salix purpureae L. var helix (L.) Koch.
Preparation It may be prepared either from salicin by melting with benzoic anhydride, or from salicin and benzoyl chloride in the presence of KOH as shown below:
Description It occurs as white needles having a sweet taste like licorice. It is readily soluble in alcohol and hot water, but sparingly soluble in cold water and almost insoluble in solvent ether.
Chemical Constituents Populin on hydrolysis with alkalies [eg., Ba(OH)2] yields salicin and benzoic acid, whereas, its hydrolysis in an acidic medium gives benzoic acid, saligenin and glucose. However, its enzymatic hydrolysis with taka-diastase provides salicin and monobenzoyl glucose.
Chemical Tests It gives exactly identical reactions with conc. H2SO4 and Frachde’s Reagent as those with salicin.
