Crystallise the salt from the minimum volume of hot water containing a few drops of stannous chloride in an equal weight of hydrochloric acid (to reduce atmospheric oxidation). Filter the solution and add half its volume of conc HCl and set aside. The salt crystallises almost quantitatively. Dry it in a vacuum in the dark (m 260o). The salt is more stable than the free base which has m 150o (darkening at 130o) and its O-methyl ether has m 49o and b 159-159o/9mm. [Desai et al. J Chem Soc 324 1938, Beilstein 13 H 666, 13 I 268, 13 II 408, 13 III 1875, 13 IV 2080.]
