18C6 AND DC18C6 CROWN-ETHERS AS SYNERGIC AGENTS IN THE EXTRACTION OF Co(II) AND Ni(I) FROH CHLORIDE MEDIA WITH 1-PHENYL.-3-HETHIL.-4-BENZOYLPYRAZOL.-5-ONE IN TOLUENE

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Abstract
The synergic extraction of Co(ll) and Ni(Il) with 1-phenyl-3-methyl-4-benzoylpyrazol-5-one (HPMBP) in presence of crown-ether (Cw) 18C6 or DC18C6 (cis-syn-cis and cis-anti-cis isomers) in toluene from 1M chloride medium is quantitatively described. A slope analysis of the distribution curves shows that the composition of the extracted species depends on the cations found in the aqueous solution : from a LiCl or (CH3.)NC14 solution, the extracted species are M(PMBP) 2.Cw (M = Co, Ni) whereas the KCw+,M(PMBP)3 ion pair is extracted from 1M KC1 solution. In the two cases, higher D-values in extraction with DC18C6 are only due to a poorer lipophilicity of 18C6; both ethers are weaker synergists than lipophilic ammonium salts.