IONIC-STRENGTH DEPENDENCE OF FORMATION-CONSTANTS .16. PROTONATION OF SOME NITROPHENOLS AND DIHYDROXYBENZOIC ACIDS IN AQUEOUS (TETRAETHYLAMMONIUM IODIDE) SOLUTION AT 25-DEGREES

The protonation of 2- and 3-nitrophenol (NO2ph) and 2,X and 3,Y dihydr oxybenzoic acids (DBA, X = 4,5,6; Y = 4,5) has been studied potentiome trically in aqueous tetraethylammonium iodide solutions, at T = 25-deg rees in the ionic strength range 0.05 less-than-or-equal-to I less-tha n-or-equal-to 1M. Besides the species reported in the literature, we h ave also found some dimeric species of 2,4-DBA and 2,5-DBA. Also for t his type of ligand, a simple equation for the dependence on ionic stre ngth of protonation constants, already proposed for several inorganic and organic acids, has been used successfully. Moreover the behavior o f protonation constants as a function of I can give information about the formation of polymeric species.