The separation and isolation of many of the platinum group metals (PGMs) is currently achieved commercially using solvent extraction processes. The extraction of rhodium is problematic however, as a variety of complexes of the form [RhCln(H2O)6‐n](n−3)− are found in hydrochloric acid, making it difficult to design a reagent that can extract all the rhodium. In this work, the synergistic combination of a primary amine (2‐ethylhexylamine, LA) with a primary amide (3,5,5‐trimethylhexanamide, L1) is shown to extract over 85 % of rhodium from 4 M hydrochloric acid. Two rhodium complexes are shown to reside in the organic phase, the ion‐pair [HLA]3[RhCl6] and the amide complex [HLA]2[RhCl5(L1)]; in the latter complex, the amide is tautomerized to its enol form and coordinated to the rhodium centre through the nitrogen atom. This insight highlights the need for ligands that target specific metal complexes in the aqueous phase and provides an efficient synergistic solution for the solvent extraction of rhodium.
The mechanism of palladium-catalysed carbene insertion cross-coupling reactions was studied by variable time normalisation analysis (VTNA), NMR spectroscopy, tandem eletrospray ionisation-mass spectrometry (ESI-MS), and density functional theory calculations. VTNA revealed...
Simple primary amides and amines have been shown to operate in tandem to synergistically transport both inner‐ and outer‐sphere rhodium chloridometalate complexes from aqueous hydrochloric acid into an organic phase in solvent extraction experiments. The complexes have been identified using a range of analytical, spectroscopic, crystallographic, and computational techniques. More information can be found in the Full Paper by C. A. Morrison, J. B. Love, et al. (DOI: 10.1002/chem.202100630).
Society requires metals for a wide range of applications, with almost every metal having an industrial application. Solvent extraction processes, originally designed for the recovery of uranium from spent nuclear waste, can provide a sustainable means of separating and purifying metals from primary and secondary sources. It is important to understand the mode of action of current systems to aid the rational design of new, more efficient solvent extraction processes as demand for metal separation technology grows. Herein, we review the application of a variety of computational techniques in understanding and developing solvent extraction processes. The use of classical and quantum mechanical models to study both the aqueous and organic phases, as well as the phase boundary, is considered.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.