Purification Methods
The dl-form is dimorphic; it crystallises from CHCl3 with m 116-117o, and from H2O with m 123o. The l(-)-enantiomer (from Actinomyces) crystallises from H2O, MeOH (m 139-140o), aqueous EtOH (m 140-141o) or EtOAc, and has [] D 20 -54o (c 1, MeOH). The d(+)-enantiomer (from optical resolution of the brucine salt) has m 138-139o (from H2O) and [] D 25 +57o (c 1, MeOH). The optically active acids racemise in hot alkali. [McLamore et al. J Am Chem Soc 75 105 1953, Beilstein 27 III/IV 4281.]
