Use
Lithocholic acid can be purified by conversion to the rather insoluble Na or K salt by addition of the equivalent amount of aqueous NaOH or KOH, filtering off the alkali salt, washing it with ice cold H2O, dissolving it in the least volume of boiling H2O, acidifying with the dilute HCl (slight excess), filtering off the acid, washing with cold H2O and drying it thoroughly in a vacuum. Recrystallise it from Me2CO, EtOH or acetic acid. The methyl ester crystallises from MeOH, with 0.5 mol of MeOH, and has m 92-93o, [] D 25 +34o (MeOH). It has also been purified by recrystallisation from pet ether (b 40-60o) and, after chromatography on Al2O3 in pet ether, gave a labile form m 92-93o which is transformed to the stable form m 125-126o after standing for 2days in a vacuum desiccator. [Hoelm & Mason J Am Chem Soc 62 569 1940, Sarel & Yanuka J Org Chem 24 2018 1959, Beilstein 10 IV 785.]