Purification Methods
Dissolve the dye in EtOH (1.16g in 30mL), filter and add aqueous NH3 till neutral (colourless) and precipitate it by adding H2O giving 0.8g, m 247o(dec, sintering at 230o). Dissolve it in EtOH, neutralise with NH3 till colourless, add 0.1g of charcoal, filter, and repeat, then add H2O (100mL) to precipitate the colourless carbinol (pseudo-base) and dry it in vacuo, m 257o(dec, also 205o, sintering at 232o). [Weissberger & Theile J Chem Soc 148 1934.] The carbinol is slightly soluble in H2O but is soluble in acids (e.g. HCl to give the coloured chloride [569-61-9]) and EtOH [pK: Goldacre & Phillips J Chem Soc 172 1949]. The perchlorate (dark red with a green shine) has m 300o and explodes at 317o [Dilthey & Diaklage J Prakt Chem [2] 129 1931]. [Beilstein 13 IV 2283.]
