THE SOLUBILITIES OF THE l-DIHALOGENATED TYROSINES IN ETHANOL-WATER MIXTURES AND CERTAIN RELATED DATA.

1. The solubilities of l-tyrosine, dichloro-l-tyrosine (hydrated), dibromo-l-tyrosine (anhydrous), and diiodo-l-tyrosine in ethanol-water mixtures at 25 degrees have been determined. 2. It was found that the solubilities of the dihalogenated substitution products of l-tyrosine are increased by addition of ethanol up to a certain concentration. Further addition of ethanol leads to a decrease in solubility. The solubility of l-tyrosine is decreased by addition of ethanol. 3. Dichloro-l-tyrosine (hydrated) was found to change to the anhydrous form when allowed to stand in the presence of ethanol. 4. The apparent heat of solution of diiodo-l-tyrosine in an ethanol-water mixture has been determined. 5. The solubility of dl-thyroxine at 30 degrees has been determined in urea solution, ethanol, dioxan, ethylene glycol, and propylene glycol.