The Solvent Extraction of Iron(III) from Chloride Solutions byN,N′‐Tetrasubstituted Malonamides: Structure‐Activity Relationships

Abstract

The extraction of iron(III) from chloride solutions has been investigated using N,N 0 -dimethyl-N,The main aim of this work was to investigate whether there is a relation between the chemical structure of malonamides and their iron(III) extraction behavior, and to try to understand the dependence of the metal extraction mechanism on the structural characteristics of the malonamides. The introduction of an alkyl chain on the central carbon atom of N,N 0 -dimethyl-N,N 0 -diphenyl skeleton malonamides increases the affinity of the organic derivatives for iron(III) at lower hydrochloric acid concentrations: the longer the alkyl chain, the lower the acidity of half of the extraction of iron(III) is. A similar behavior has been observed both for DMDCMA and DMDHMA when N,N 0 -dimethyl-N,N 0 -diphenylmalonamide (DMDFMA) is taken as a reference. The collected spectroscopic results point out that either the presence of a central alkyl chain on N,N 0 -dimethyl-N,N 0 -diphenyl skeleton malonamides or the replacement of the N,N 0 -diphenyl groups by dicyclohexyl-or di-n-hexyl ones, likely determines iron(III) extraction through a solvation pathway, also involving the extraction of HCl molecules.

Palladium Isolation and Purification from Nitrate Media: Efficient Process Based on Malonamides

“…The purpose of this article is to present in detail the design of a malonamide based solvent, that enables selective Pd(II) extraction, in the presence of base metals, such as Fe(III), Al(III), Zn(II), Cu(II), Ni(II), Co(II) and lanthanides, especially Nd(III). As previous reports on closely related N,N'-tetrasubstituted malonamides, bearing or not an alkyl chain on the central carbon atom, reported that Fe(III) can be very efficiently extracted [24][25][26], we focused part of our study on the Pd(II)/Fe(III) separation. We also explored the scope and limitations of this solvent, with regard to some other potentially usable solvents based on commercially available extractants, tributylphosphate (TBP), dihexylsulfide (DHS), and bis(2-ethylhexyl)sulfoxide (BESO).…”

Liquid–Liquid Extraction of Silver From Chloride Media byN,N′-Tetrasubstituted Dithiomalonamide Derivatives

“…It would be worthwhile, if one takes the environmental point of view into account, that alternative extractants with similar efficiency and selectivity patterns as the phosphorus ones could be found. Having that idea in mind, and after an extensive use of N,N 0 -tetrasubstituted malonamide derivatives to recover some metal ions (Fe(III) (18), Rh (19), and Pt (20)), it was decided to carry out the synthesis of two model N,N 0 -tetrasubstituted dithiomalonamides and check their efficiency and selectivity towards Ag(I) in chloride media.…”

“…N,N 0 -dimethyl-N,N 0 -diphenyldithiomalonamide (DMD-PHDTMA) and N,N 0 -dimethyl-N,N 0 -dicyclohexyldithiomalonamide (DMDCHDTMA) were obtained from their correspondent malonamides, N,N 0 -dimethyl-N,N 0 -diphenylmalonamide (DMDPHMA) and N,N 0 -dimethyl-N,N 0 -dicyclohexylmalonamide (DMDCHMA), whose synthetic and characterization details have already been published (18).…”

Liquid-Liquid Extraction of Platinum from Chloride Media byN,N′-Dimethyl-N,N′-Dicyclohexyltetradecylmalonamide

“…[24,25] DMDCHTDMA was synthesized from the latter also by a described method [24] : DMDCHMA (9 g, 0.031 mol) was dissolved in 25 mL of toluene, in a round bottom flask. Sodium hydride (2.16 g, 0.054 mol) was added under stirring, and the mixture was refluxed for 2 h. The reaction mixture was allowed to cool down to room temperature and a solution of bromotetradecane (8.5 mL, 8.49 g, 0.031 mol) in 20 mL of toluene was added dropwise.…”