ANALYTICAL AND SPECTROSCOPIC STUDY OF ZINC EXTRACTION WITH 1, 10-BIS[1-PHENYL-3-METHYL-5-HYDHOXY-1-PYFAZOLYL]-1,10-DECANEDIONE AND THI-n-OCTYLPHOSPHINE OXIDE.

Abstract

Abstract Zinc extraction from perchlorate medium, with 1, 10-bis[ 1-phenyl-3-methyl-5-hydroxy-4-pyrazolyl]-1,10-decanedione (HL-8-LH) and its mixtures with tri-n-octylphoaphine oxide (TOPO) in chloroform has been investigated and compared with the corresponding extraction systems with 1-phenyl-3-methyl-4-benzoyl-pyrazol-5-ol (HL*). The extraction processes are: Zn2+ + 2 HL-8-LH 3* 2 H+ + Zn(L-8-LH) (K ) -3.24(25°) and -2.80(30°); log K' 121= -2.35(25°); log Ki: ±0.1. HL-8-LH is a slightly better extractant than HL', due to the higher lipophilicity of the extracted complexes. For high values of [Zn], in both extraction systems, a third solid phase forms: it consists of the bis-chelate Zn(L-8-L)(H2O) (IR study). A quantitative PMR study of synthetic solutions “Zn(L-8-L)(H2O) + × TOPO”, in wet CDC13, gives evidence of the occurrence of the complexes Zn(L-8-L)(TOPO) and Zn(L-8-L)(TOPO)2. Only the former is clearly characterized in the extraction phases. In those systems, the influence of coordination upon TOPO has been estimated by phospho-rus-31 NMR. The L-8-L entity, coordinated on zinc by both ends, shows steric constraints in Zn(L-8-L)(H2O) or Zn(L-8-L)(TOPO) that disappear in Zn(L-8-L)(TOPO)2.