THE EXTRACTION TRANSFER OF H+-18-CROWN-6 SPECIES ACROSS THE WATER NITROBENZENE PHASE-BOUNDARY IN THE EXTRACTION OF AQUEOUS-SOLUTIONS OF PERCHLORIC-ACID BY NITROBENZENE IN THE PRESENCE OF 18-CROWN-6

A study was made of the extraction of perchloric acid in water-nitrobenzene and water-nitrobenzene-18-crown-6 (hereafter L) systems. The experimental data was interpreted on the basis assumption that the extraction occurs according to the equations H(aq)+ + ClO4,aq- half arrow right over half arrow left H(org)+ + ClO4,org- and H(aq)+ + L(aq) + ClO4,aq- half arrow right over half arrow left HL(org)+ + ClO4,org-. Crown is also protonated in the aqueous phase according to the equation H(aq)+ + L(aq) half arrow right over half arrow left HL(aq)+. The values of the corresponding extraction constants, the protonation constants of 18-crown-6 in nitrobenzene and water and the individual extraction constants of the HL+ species in the water-nitrobenzene system were determined, along with the magnitude of the molar free enthalpy for the transfer of these species across the given phase boundary.