Purify it by dissolving in 50 parts of H2O, shaking with a small excess of freshly precipitated and washed Ag2O. The mixture is set aside overnight at 0o and filtered. The cake is not washed. The pH of the filtrate is adjusted to 7.0 with HCl and evaporated to dryness. The residue is then crystallised twice from MeOH, twice from H2O and dried at 120o. at 452nm has a log value of 4.67. Itis ared max powder which readily absorbs H2O. The solubility is increased in the presence of proflavin. The dihydrochloride is a deep red crystalline powder. It is available as a mixture of 3,6-diaminoacridinium chloride (35%) and its 10-metho-chloride (65%). [See Albert, The Acridines Arnold Press p 346 1966, Benda Chem Ber 45 1787 1912]. [Beilstein 23 I 650.]
