The acid crystallises from 50% aqueous EtOH. The hydrochloride has m 218-220o(dec). The N-benzoyl derivative has m 204-205o (from MeOH) and the N-benzoyl-hydrazide has m 226-227o (from MeOH or EtOH). [Posner Justus Liebigs Ann Chem 389 44 1912, Beilstein 14 I 603, 14 IV 1548.]
