Solvent extraction of silver picrate by 3m-crown-m ethers (m = 5, 6) and its mono-benzo-derivative from water into benzene or chloroform: elucidation of an extraction equilibrium using component equilibrium constants

Ion-pair formation constant (KAgPic in mol−1 dm3) of silver picrate (AgPic), those (KAgLPic) of its ion-pair complexes (AgLPic) with crown ethers (L) and complex formation constants (KAgL) of Ag+ with L (15-crown-5 ether (15C5) and benzo-15C5) in water (w) were determined potentiometrically at 25 °C. Compounds used as L were 18-crown-6 ether (18C6), its benzo-derivative (B18C6) and the two 15C5 derivatives. Extraction constants (Kex in mol−1 dm3) of AgPic with L (15C5, 18C6, B18C6) from acidic w-phases into either C6H6 or CHCl3 were recalculated from KAgPic, KAgL, KAgLPic and data opened in previous papers. Thus obtained Kex was divided into five component equilibrium constants containing KAgL and KAgLPic anew. Then, contributions of the component constants, KAgL, KAgLPic and distribution constants of AgLPic between the w- and C6H6-phases, to Kex were discussed and compared with corresponding extraction systems of NaPic and KPic with18C6.