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The evaluation of bis-1,2,4-triazine complexants containing eight-carbon, alkoxy-functionalized phenyl substituents at the 3,3′-positions for selective minor actinide extraction in simulated high level waste is reported. The complexant retained chemoselective extraction efficiency of actinides over lanthanides while breaking through the nonpolar diluent solubility and hydrolytic stability barriers that limit many BTP complexants. Thus, we report a BTP complexant that is readily soluble in both kerosene and isooctanol without forming precipitates, emulsions, or third phase after contact with nitric acid and extracts 241Am3+ from 154Eu3+. Separations and spectroscopic data are reported herein. [ABSTRACT FROM AUTHOR]

Continued pursuit of functionalized soft‐N‐donor complexant scaffolds with favorable solubility and kinetics profiles applicable for the separation of the trivalent minor actinides from the lanthanides has attracted significant interest over the last three decades. Recent work from this laboratory resulted in the production of various N‐Boc protected [1,2,4]triazinyl‐pyridin‐2‐yl indole Lewis basic procomplexants which necessitated the removal of the indole N‐Boc protecting group prior to evaluation of complexant efficacy in separations assays. Traditional deprotection strategies involving trifluoroacetic and other protic and Lewis acids proved unsuccessful in removal of the recalcitrant indole‐N‐Boc protecting group necessitating the development of a new strategy for deprotection of this complexant class. A serendipitous result facilitated utilization of 3‐methoxypropylamine as a mild deprotecting agent for various N‐Boc protected heteroarenes via a proposed addition–elimination mechanism. Method development, application to various heteroarenes including indoles, 1,2‐indazoles, 1,2‐pyrazoles, and related derivatives, a ten‐fold scale‐up reaction, and experimental evaluation of a preliminary mechanistic hypothesis are reported herein. [ABSTRACT FROM AUTHOR]

Current efforts in this laboratory continue to focus on the preparation of novel complexant motifs for potential use in chemoselective minor-actinide liquid–liquid separations of relevant cations from used nuclear fuel. The present work describes an efficient Pd-catalyzed amination reaction of diversely functionalized 6-bromo-1,2,4-triazinyl-pyridine scaffolds with various amines to afford the opportunity for convergent modulation of complexant electronic and steric properties directly from one substrate towards potentially enhanced solubility in process-relevant solvents. The 21 novel examples presented highlight a unified approach to extensive molecular diversity and provide the ability to further study chelate effects, solubility properties, and complexation efficacy on nonsymmetric, moderately soft-Lewis-basic complexant scaffolds without the incorporation of additional heteroaromatic moieties. Synthetic-method optimization, amine and scaffold scope, as well as a scale-up experiment are presented. [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]

As part of ongoing efforts in this laboratory to design and synthesize multidentate soft-N-donors as effective complexants for chemoselective minor actinide extraction from used nuclear fuel, a series of aminated mono-1,2,4-triazinylpyridines were required. This study focuses on streamlining convergent access to a diverse array of functionalized N-donors using Pd-catalysis from a common synthon affording access to pyridinyl triazines as the 4,4'-amino derivatives which are commercially limited and unsuccessful in traditional condensation chemistry. A general Pd-catalyzed method for the double amination of functionalized pyridinyl-1,2,4-triazines with low catalyst/ligand loadings enabling the formation of 16 novel complexants is presented. [ABSTRACT FROM AUTHOR]