Multi-loading ligand assemblies to transport copper

• Main Author: Wood, Jenny Lynne
• Published: University of Edinburgh 2005
• Subjects: 622
• Online Access: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.663992

The thesis contains work aimed at improving the copper transport-efficiency shown by the commercial phenolic oxime reagents which are surveyed in chapter 1. New solvent extractants based on ligands which are diacids and can thus form neutral complexes with divalent copper that have a 1:1 ligand to metal stoichiometry, instead of the 2:1 stoichiometry shown by conventional reagents, are reported. The design, preparation and copper(II) extraction capabilities of a series of 3-substituted 2-hydroxy-5-alkyl-benzaldehyde-octanoylhydrazones are described in chapter 2. Chapter 3 considers the complex tautomerism of series of 3-alkyl-4-(2’hydroxy-5’-alkylphenylenamine)-pyrazol-5-ones and their ability to extract copper(II). The addition of certain non-chelating neutral auxiliary ligands is shown in chapter 4 to enhance copper(II) loading by both hydrazone and pyrazolone ligands. Addition of 2-ethylhexanal oxime in a 3:1 ratio, results in enhancement of copper(II) extraction for all ligands tested and the formation of 1:1:1 ligand to copper(II) to 2-ethylhexanal oxime complexes is indicated by EPR spectroscopy. Addition of 3-ⁱpropyl-2-pyrazol-5-one to the 3-nitro- and 3-hydro- substituted hydrazone ligands in a 1:1 ratio, produces a similar effect. Hydrogen bonding fro the auxiliary ligands to the phenolate pyrazolonato and/or hydrazonato oxygen atoms is proposed in these ternary complexes. Inter-ligand hydrogen-bonding is also proposed in most of the binary complexes discussed in chapters 2 and 3 and it is suggested that rational design of new simple extractants for base metals should exploit this feature in enhancing both strength and selectivity of new reagents.