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The effective partitioning and transmutation of the minor An from the Ln in spent nuclear fuel in a non-proliferative manner is critical to lowering potential impact to the environment, moderating concern over the increase of nuclear power as a green alternative to fossil fuels, and solving a grand challenge in separation science. Although present in less than.1 wt.%, Am and Cm represent half-lives of over 400 years and significantly contribute to heat load through radioactive decay. Separation of the minor An from the neutron-poisoning Ln can advance the nuclear fuel cycle further toward closure and decrease the volume and radiotoxicity of daughter nuclides stored in a geologic repository. Similar physical properties and metal-complexant binding phenomena render this separation difficult. In this work, a comprehensive liquid-liquid separations study using the recently discovered 3,3'-butyloxy-bis-1,2,4-triazinyl-2,6-pyridine in the polar aprotic solvent trifluoromethylphenyl sulfone is presented. Unlike contemporary bis-1,2,4-triazinyl-2,6-pyridine complexants, the current system is stable and performs well in highly acidic systems. Separation of 241Am3+ from 154Eu3+, acid range tolerance, complexant concentration, and decomplexation studies are presented herein. [ABSTRACT FROM AUTHOR]

Functionalization of pyridines with the carbonitrile group for advanced cyclization reactions routinely incorporates metals, toxic oxidants, and cyanide reagents, often in linear synthetic sequences. Motivated by the strategic need of a heteroaryl carbonitrile synthon for further elaboration, we disclose an efficient, metal‐free, one‐pot reaction sequence that uses ammonium acetate as the nitrogen source and bis‐acetoxyiodobenzene as the oxidant with low loadings. The developed method tolerates a diverse substrate scope including heteroaryl, aryl, and alkyl substrates with similar efficiency and expands the practitioner's reaction. Method development, optimization, substrate scope, preliminary mechanistic observations, competition experiments, and a scale up reaction are delineated herein. [ABSTRACT FROM AUTHOR]

The development of liquid-liquid separation processes for the effective removal of minor actinide Am(III) from used nuclear fuel (UNF) using ligand-based strategies continues to be an area of significant research focus. The current investigation demonstrates the efficacy of a nitrogen-based bis-triazinyl pyridine (BTP) derivative to selectively extract Am(III) from nitric acid solutions containing light lanthanides. The performance of 3,3ʹ-dimethoxy-phenyl-bis-1,2,4-triazinyl-2,6-pyridine (MOB-BTP) was compared to that of a camphor-substituted BTP (CA-BTP). The results of this investigation demonstrate the novel 3,3ʹ-methoxy-BTP extractant dissolved in a polar diluent was a more efficient extractant for Am(III) at a lower concentration than CA-BTP under comparable conditions. [ABSTRACT FROM AUTHOR]

The development of materials for efficient chemoselective extraction of minor actinides remains at the forefront of research efforts in the area of separation science. Lewis basic complexants derived from nitrogen-donor scaffolds are often employed in this area due to favorable with the transuranic element americium. In the present work an efficient procedure for the preparation of eight useful 3-pyridin-2-yl-1,2,4-triazines (2 novel) is demonstrated via telescoped condensation with the requisite 1,2-dicarbonyl in two-pots without additives, differentially extractive work-up procedures, or recrystallization. Additional efforts in this area have demonstrated the utility of polar aprotic solvents for the preparation of nine functionalized pyridinyl-2,6- bis-1,2,4-triazines (4 novel) directly from the requisite 2,6-pyridine dicarbonitrile in 49-99% yield over four total steps. The streamlined preparation of these important materials and detailed synthetic procedures is reported herein. [ABSTRACT FROM AUTHOR]

Remediation or transmutation of spent nuclear fuel obtained as a function of energy production and legacy waste remains a significant environmental concern. Substantive efforts over the last three decades have focused on the potential of soft-Lewis basic complexants for the chemoselective separation of trivalent actinides from lanthanides in biphasic solvent systems. Recent efforts in this laboratory have focused on the concept of modularity to rapidly prepare complexants and complexant scaffolds not easily accessible via traditional linear methods in a convergent manner to better understand solubility and complexation structure/activity function in process-relevant solvents. The current work describes an efficient method for the construction of diversified complexants through multi-Suzuki-Miyaura cross-coupling of bromoheteroarenes with organotrifluoroborates affording efficient access to 22 novel materials in 43-99% yield over two, three, or four cross-couplings on the same scaffold. Optimization of the catalyst/ligand system, application, and limitations are reported herein. [ABSTRACT FROM AUTHOR]

Among the different components present in spent nuclear fuel, long-lived trivalent actinides are particularly difficult to separate from the shorter-lived lanthanide fission products due to their similar chemical properties. Selective extraction of americium from acidic solution (up to 2M HNO3) containing tenth molar quantities of lanthanides has been achieved using neutral pyridine-based ligands dissolved in polar diluents. Nitrogen-based Bis Triazinyl Pyridine (BTP) ligands are desirable for both their excellent An/Ln selectivity and incinerability. Results pertaining to ligand solubility, kinetics, hydrolytic stability, and extraction performance in various nitric acid environments are presented. [ABSTRACT FROM AUTHOR]

Efficient separation of minor actinides from spent nuclear fuel remains a formidable challenge. As part of ongoing efforts to identify effective ligands for separation of toxic radionuclides, a series of bis-1,2,4-triazines, three novel, have been prepared from [1,10]-phenanthroline-2,9-dicarbonitrile in two-telescoped steps without additives, complicated workups, prolonged reaction times, or additional purification. [ABSTRACT FROM AUTHOR]

Soft-Lewis basic complexants that facilitate chemoselective separation of the minor actinides from the lanthanides are critical to the closure of the nuclear fuel cycle. Complexants that modulate covalent orbital interactions with relevant metals of interest can facilitate desired outcomes in liquid-liquid separation, allowing for further transmutative processes that decrease issues related with storage of spent nuclear fuel from energy and weapons production. Synthesis of previously unexplored scaffolds seeks to improve performance over benchmark complexants. In the current work, an intermolecular, thermally initiated, and DBU-assisted [3 + 2] cycloaddition of 3-(6-ethynyl-pyridin-2-yl)-5,6-diphenyl-[1,2,4]triazine dipolarophiles with structurally diverse 4-methylbenzenesulfono-hydrazides afforded 21 yet-to-be reported examples in 42-68% yield and modest regioselectivity for the desired regioisomer. Preparation of requisite starting materials, method definition, dipole and dipolarophile scope, ten-fold scale-up reaction, and downstream functional group interconversion are reported herein.