Biogastrone,Winthrop,UK,1963
23.5 g of glycyrrhetinic acid were dissolved in 50 cc of dry pyridine. A solution
of 6.0 g of succinic anhydride in 30 cc of dry pyridine was added, followed by
30 cc of dry triethylamine and then, for washing purposes, 5 cc of dry
pyridine. The solution was heated on a boiling water bath for ten hours and
then poured into excess of dilute hydrochloric acid and ice. The fine gray
precipitate formed was filtered off, washed with water, dissolved in chloroform,
and the solution repeatedly extracted with dilute hydrochloric acid and later
with water. It was dried over sodium sulfate and evaporated to dryness.
Crystallization from methanol, using charcoal to effect decolorization, gave the
hydrogen succinate as cream-colored crystals, MP 291° to 294°C, with
previous softening.
One molecular proportion of glycyrrhetinic acid hydrogen succinate was
ground with a dilute (5%) aqueous solution containing two molecular
proportions of sodium hydroxide. The solution was filtered and evaporated in
vacuum over concentrated sulfuric acid. The sodium salt is then obtained as a
creamy white water-soluble solid. Glycyrrhetinic acid is obtainable from
licorice root.
