It crystallises from H2O, MeOH or MeOH/Et2O (charcoal) in colourless prisms that become green on heating. [Elvidge & Linstead J Chem Soc 5000 1952]. IR (nujol): 3150 and 690 cm-1 , and UV: max 251nm ( 12,500), 256nm ( 12,5000) and 303nm ( 4,600) [Elvidge & Golden J Chem Soc 700 1957, Clark et al. J Chem Soc 3593 1953]. The thiocyanate has m 250-255o (dec), the monohydrochloride has m 300-301o (turns green), and the dihydrochloride has m 326-328o (turns green) and the picrate crystallises from EtOH with m 299o (dec). [Beilstein 22/13 V 5.]
