The Solubilities, Apparent Dissociation Constants, and Thermodynamic Data of the Dihalogenated Tyrosine Compounds

1. The solubilities and differential heats of solution of d-tyrosine, dl-tyrosine, diiodo-dl-tyrosine, dibromo-l-tyrosine (hydrated), dibromo-l-tyrosine (anhydrous), and dichloro-l-tyrosine (hydrated) have been determined. 2. Evidence has been advanced that dl-tyrosine is a compound. 3. From the solubility determinations at various acidities, the apparent acid and basic dissociation constants of dibromo-l-tyrosine and dichloro-l-tyrosine have been determined at 25 degrees and 40 degrees C. From these data the apparent heats of ionization have been calculated. 4. The question concerning which of the groups in l-tyrosine and its dihalogenated substitution products is responsible for each dissociation constant has been discussed.