Synthesis and Coordination Properties of Multifunctional Carbamoylmethyl Phosphonates

Abstract

Bifunctional carbamoylmethylphosphonates are useful extractants for lanthanide and actinide ions and the structural mechanics involved in extraction processes have been under study in our laboratory. We have recently prepared several new multifunctional ligands of the general types (RO)₂P(O)CH[C(O)NR₂][CH₂C(O)NR₂], [(RO)₂P(O)]₂CHCH₂C(O)NR₂ and [(RO)₂P(O)CHC(O)NEt₂]₂CH_2. The syntheses and characterization data for the new extractants will be described. The coordination chemistry of these ligands with lanthanide and actinide ions has been studied and crystal structure determinations for selected complexes will be shown. Lastly, liquid-liquid extraction distribution measurements for several ligands with lanthanide ions will be presented.     

H‐transfer reaction during decomposition of N‐(2‐methylpropyl)‐ N‐(1‐diethylphosphono‐2,2‐dimethylpropyl)‐N‐oxyl (SG1)‐based alkoxyamines

Thermal decomposition of four tertiary N‐(2‐methylpropyl)‐N‐(1‐diethylphosphono‐2,2‐dimethylpropyl)‐N‐oxyl (SG1)‐based alkoxyamines (SG1‐C(Me)₂‐C(O)‐OR, R = Me, tBu, Et, H) has been studied at different experimental conditions using ¹H and ³¹P NMR spectroscopies. This experiment represents the initiating step of methyl methacrylate polymerization. It has been shown that H‐transfer reaction occurs during the decomposition of three alkoxyamines in highly degassed solution, whereas no products of H‐transfer are detected during decomposition of SG1‐MAMA alkoxyamine. The value of the rate constant of H‐transfer for alkoxyamines 1 (SG1‐C(Me)₂‐C(O)‐OMe) and 2 ( SG1‐C(Me)₂‐C(O)‐OtBu) has been estimated as 1.7 × 10³ M^?1s^?1. The high influence of oxygen on decomposition mechanism is found. In particular, in poorly degassed solutions, nearly quantitative formation of oxidation product has been observed, whereas at residual pressure of 10^?5 mbar, the main products originate from H‐atom transfer reaction. The acidity of the reaction medium affects the decomposition mechanism suppressing the H‐atom transfer. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013     

Brønsted Acid Catalyzed Tandem Defunctionalization of Biorenewable Ferulic acid and Derivates into Bio‐Catechol

An efficient conversion of biorenewable ferulic acid into bio‐catechol has been developed. The transformation comprises two consecutive defunctionalizations of the substrate, that is, C?O (demethylation) and C?C (de‐2‐carboxyvinylation) bond cleavage, occurring in one step. The process only requires heating of ferulic acid with HCl (or H₂SO₄) as catalyst in pressurized hot water (250 °C, 50 bar N₂). The versatility is shown on a variety of other (biorenewable) substrates yielding up to 84 % di‐ (catechol, resorcinol, hydroquinone) and trihydroxybenzenes (pyrogallol, hydroxyquinol), in most cases just requiring simple extraction as work‐up.     

Complexation of TiF<Subscript>4</Subscript> with PhP(O)[CH<Subscript>2</Subscript>C(O)NMe<Subscript>2</Subscript>]<Subscript>2</Subscript> in CH<Subscript>2</Subscript>Cl<Subscript>2</Subscript>: Appearance of a Chiral Center at Chelate Coordination

The reaction of TiF₄ with PhP(O)[CH₂C(O)NMe₂]₂ in CH₂Cl₂ has been studied by ¹⁹F NMR spectroscopy. It has been found that the major reaction products are chelate tetrafluoro complex (η²-L)TiF₄ where the ligand is coordinated to the titanium ion through the P=O and C=O groups and cis-TiF₄(ОР···L)₂ where both ligands are coordinated to the central ion through the more basic P=O groups. Spectral features of the tetrafluoro chelate have been studied, which have been attributed for the first time to the appearance of a chiral center at chelate coordination. The character of manifestation of conformational isomerism of the chelate ring and chiral center in the chelating ligand in mixed octahedral complexes of d⁰ transition metal fluorides in ¹⁹F NMR spectra is discussed.     

N-Alkyl-N′-[(alkyl/aryl)(alkoxy/aroxy)phosphoryl]ureas: synthesis and extraction properties toward f-elements

A reaction of chlorophosphonates R¹R²P(O)Cl with NaOCN and subsequent treatment with octylamine lead to phosphorylureas R¹R²P(O)NHC(O)NHC₈H₁₇-n (R¹ = EtO, PhO; R² = Me, Ph). Their extraction capability toward U^VI and a number of tervalent lanthanides (La^III, Nd^III, Ho^III, Yb^III) was studied. Efficiency and selectivity of these ligands in the extraction of f-elements from nitric acid solutions to chloroform were compared with extraction properties of a model phosphine oxide-type phosphorylurea MePhP(O)NHC(O)NHC₈H₁₇-n and carbamoylphosphine oxide Ph₂P(O)CH₂C(O)NBu₂.     

Extraction of f-elements from nitric acid solutions with phosphoryl ketones

The extraction ability and selectivity of a series of phosphoryl ketones Ph₂P(O)CH₂C(O)Me, and Ph₂P(O)CRR’CH₂C(O)Me (R = H, Me; R’ = H, Me, n-C₅H₁₁, Ph, 2-thienyl, 2-furyl) towards trivalent lanthanides (La^III, Nd^III, Ho^III, Yb^III) and actinides (U^VI, Th^IV) were studied. The efficiency and selectivity of the new ligands in the extraction of f-elements from nitric acid solutions into chloroform were compared to those of model phosphine oxide Ph₂P(O)Bu and known extractants: tributyl phosphate (BuO)₃P(O), trioctylphosphine oxide (C₈H₁₇)₃P(O), and carbamoylmethyl phosphine oxide Ph₂P(O)CH₂C(O)NBu₂.     

Ag+ selection by aza‐18‐crown‐6 ethers N‐Substituted on heterocyclic aromatics

Substitution on the nitrogen atom, where necessary by high‐pressure S_NAr reactions, of aza‐18‐crown‐6 ethers linked to heterocyclic aromatics has extended the number of potential host compounds for Ag⁺. The complexation of Ag⁺ by the new compounds has been evaluated by liquid membrane ion transport and ion extraction experiments. The nature of the binding sites of these new host compounds for Ag⁺ has been assessed, in DMF/D₂O (4/1), by ¹³C nmr titration experiments with AgClO₄.     

1,4‐Di(isopropyl)‐1,4‐diazabutadien als Abfangreagenz für monomere Bruchstücke des Tetragalliumclusters Ga4[C(SiMe3)3]4 – Bildung eines ungesättigten GaN2C2‐Heterocyclus und eines Oxidationsprodukts mit Ga‐O‐O‐Ga‐Gruppe

1,4‐Di(isopropyl)‐1,4‐diazabutadiene as a Reagent for the Trapping of Monomeric Fragments of the Tetragalliumcluster Ga₄[C(SiMe₃)₃]₄ – Formation of an Unsaturated GaN₂C₂ Heterocycle and an Oxidation Product Containing a Ga‐O‐O‐Ga Group The tetrahedral tetragallium cluster Ga₄[C(SiMe₃)₃]₄ ( 1 ) dissociates upon dissolution to yield the monomeric fragments Ga‐R [R = C(SiMe₃)₃]. These monomers could be trapped now by the treatment of their solutions with 1,4‐di(isopropyl)‐1,4‐diazabutadiene. The product of the cycloaddition reaction ( 2 ) possesses a five‐membered GaN₂C₂ heterocycle with a coordinatively unsaturated gallium atom and an endocyclic C=C double bond. 2 is rather sensitive towards oxidation by traces of air. The contact with oxygen yielded a digallium peroxide [(C₂N₂iPr₂)RGa‐O‐O‐GaR(C₂N₂iPr₂)] ( 3 ) which was isolated in a very low yield only and which has a gallium atom attached to each oxygen atom of the inner peroxo group. Both chelating ligands of 3 possess an unpaired electron.     

Modified Raoult's law including the solvent structural constant and solute solvation; Aqueous sodium chloride solutions, 25 to 300°C; Other electrolytes and urea, 25°C

The form of Raoult's law is modified to express the activity of water [a(H₂O)] for aqueous electrolyte solutions by the mole fraction of a free (nonsolvating) solvent structural unit raised to the reciprocal power of the solvent structural constant. Relatively close agreement with experiment, is obtained for a(H₂O) of aqueous sodium chloride solutions up to 300°C and nearly saturated concentrations, and of other aqueous electrolyte solutions at 25°C. In an example for aqueous-organic systems, a(H₂O) for urea solutions at 25°C is described with an average deviation of 0.09% for molalities from 0 to 20m (54.6 wt%) by using the necessary (universal) structural constant and a single solvation parameter.     

The effect of pressure and temperature of self-diffusion coefficients in several concentrated deuterium oxide diamagnetic electrolyte solutions

The pressure dependences of the self-diffusion coefficients of deuterium oxide in 4.5m solutions of LiCl–D₂O and CsCl–D₂O (also 7m) and 3.06m CaCl₂–D₂O have been measured by the NMR spin-echo method at 30°C, 60°C, and 90°C. Shear viscosities and densities of these solutions have also been determined over the same range of experimental conditions. The experimental data show that the diffusion constantD decreases with the increasing structure-making ability of the electrolyte cation Ca⁺²>Li⁺. In contrast, the diffusion coefficient for D₂O in the 4.5 and 7m CsCl solutions is equal to that for pure D₂O at 30°C but lower at 60°C and 90°C. It has been found that the Stokes-Einstein equation relates well the diffusion coefficients to shear viscosity in these concentrated electrolyte solutions.     

Monolithic FeO<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript>/Al<Subscript>2</Subscript>O<Subscript>3</Subscript> catalysts for ammonia oxidation and nitrous oxide decomposition

(1.2–8.3)%FeO_х/Al₂O₃ monolith catalysts have been prepared by impregnating alumina with aqueous solutions of iron(III) nitrate and oxalate and have been tested in NH₃ oxidation and in the selective decomposition of N₂O in mixtures resulting from ammonia oxidation over a Pt–Rh gauze pack under conditions of nitric acid synthesis (800–900°C). In the case of the support calcined at 1200°C, the catalyst is dominated by bulk Fe₂O₃ particles localized on the Al₂O₃ surface. The activity of these samples in both reactions decreases with a decreasing active component content, thus limiting the potential of Fe₂(C₂O₄)₃ · 5H₂O, an environmentally friendlier but poorly soluble compound, as a substitute for Fe(NO₃)₃ · 9H₂O. Decreasing the support calcination temperature to 1000°C or below leads to the formation of a highly defective Fe–Al–O solid solution in the (1.2–2.7)%FeO_х/Al₂O₃ catalysts. The surface layers of the solid solution are enriched with iron ions or stabilize ultrafine FeO_х particles. The catalytic activity of these samples in both reactions is close to the activities measured for ~8%FeO_х/Al₂O₃ samples prepared using iron nitrate.     

The Influence of Sodium Phosphate on Extraction Phenomena of Aqueous Two‐Phase Cationic/Anionic Surfactant Systems

The phase behavior of dodecyltrimethylammonium bromide (DTAB)/sodium dodecyl sulfonate (AS)/H₂O system in the presence and in the absence of sodium phosphate has been studied. Two kinds of aqueous two‐phase systems (ATPSs) were formed, one is ATPS‐A in which anionic surfactant is in excess, the other is ATPS‐C in which cationic surfactant is in excess. For the CTAB/AS/H₂O system, the addition of sodium phosphate changes the extraction phenomena of both ATPS‐A and ATPS‐C. For the DTAB/AS/H₂O system, the addition of sodium phosphate changes the extraction phenomena of ATPS‐C. For ATPS‐C, the addition of trivalent PO₄ ^3? results in a strong extraction effect of ATPS‐C to cationic water‐soluble dye methylene blue.     

Solubility in the NdCl3-LnCl3-HCl-H2O systems (Ln = Sm, Gd) at 25°C

The solubility at 25°C in the NdCl₃-SmCl₃-HCl-H₂O and NdCl₃-GdCl₃-HCl-H₂O quaternary water-salt systems has been studied in 40% hydrochloric acid sections. The NdCl₃-SmCl₃-HCl-H₂O system represents a continuous series of solid solutions (type I solid solutions). The NdCl₃-GdCl₃-HCl-H₂O system is a system with peritonic discontinuity (type V solid solutions). The discontinuity point of the peritonic solution has the following composition (wt %): NdCl₃ · 6H₂O, 1.13; GdCl₃ · 6H₂O, 0.11; HCl, 39.5; H₂O, 59.26.     

Conversion of neodymium oxide with N<Subscript>2</Subscript>O<Subscript>4</Subscript> into nitrate followed by supercritical fluid extraction of nitrate

A novel method that spent nuclear fuel is converted into nitrates with N₂O₄, and then nitrates are extracted with TBP in supercritical CO₂ (SC-CO₂), has been developed for reprocessing of spent nuclear fuel, which has a potential prospect because of its potential to decrease generation of the secondary liquid waste. In this paper, conversion of Nd₂O₃ with N₂O₄ into its nitrate under various conditions and extraction of the conversion product with TBP in SC-CO₂ were investigated. When temperature was 60–120 °C, the molar ratio of H₂O to Nd₂O₃ was from 1 to 6, and molar ratio of N₂O₄ to Nd₂O₃ was above 8, complete conversion of Nd₂O₃ into its nitrate was achieved. The conversion product was characterized by thermal analysis (TG-DTA), X-ray diffraction (XRD), Fourier transformed infrared spectroscopy (FT-IR) and Raman spectroscopy. Quantitative extraction of the conversion product with TBP in supercritical CO₂ was also achieved under experimental conditions.     

Extraction of U(VI) and Th(IV) from nitric acid medium using tri(butoxyethyl) phosphate (TBEP) in <Emphasis Type="Italic">n</Emphasis>-paraffin

Extraction behavior of U(VI) and Th(IV) from nitric acid medium is investigated using organo-phosphorous extractant, tri(butoxyethyl) phosphate in n-paraffin at room temperature (27 ± 1 °C). The effect of diluents, nitric acid concentration as well as extractant concentration on extraction of U(VI) and Th(IV) are evaluated. Extraction of U(VI) and Th(IV) from nitric acid medium proceeds via solvation mechanism. Slope analysis technique showed the formation of neutral complexes of the type of UO₂(NO₃)₂·2TBEP and Th(NO₃)₄·3TBEP with U(VI) and Th(IV) respectively in the organic phase. The FTIR data showed shifting of P=O stretching frequency from 1,282 to 1,217 cm⁻¹ indicating the strong complexation of P=O group with UO₂ ²⁺ ions in the organic phase. Effect of stripping agents, other metal ions and their separation with respect to U(VI) extraction has also been investigated.     

3,3′‐Seleno­bis­(propionic acid)

In contrast to Se[CH₂C(O)OH]₂versus S[CH₂C(O)OH]₂, the title compound, Se[CH₂CH₂C(O)OH]₂ or C₆H₁₀O₄Se, is structurally quite similar to its sulfur analogue. The mol­ecule has twofold symmetry. The C—Se—C bond angle is 96.48 (8)° and the Se—C bond lengths are 1.9610 (14) Å. The shortest Se?O intermolecular distance is 3.5410 (11) Å. The O?O distances in the carboxyl­ic acid dimers are 2.684 (2) Å. The temperature dependence of the IR spectrum suggests tautomerism in the solid state.     

Solvent extraction of chromium(VI) from base metal ions with diphenyl-2-pyridylmethane as a liquid anion exchanger

The extraction of chromium(VI) from aqueous hydrochloric, nitric and sulfuric acid solutions by diphenyl-2-pyridylmethane(DPPM) dissolved in chloroform has been studied. Chromium(VI) is quantitatively extracted from hydrochloric acid solutions in the range 0.1–1M. With increasing acid concentration, the extraction of chromium diminishes and in concentrated acid solutions practically all the chromium remains in the aqueous phase. The quantitative back-extraction of chromium from the organic phase is possible with HCl or HNO₃ at concentrations higher than 5M through the use of reducing agents. The composition of the extracted chromium(VI) species was studied in solution. The complexes (DPPMH)⁺HCrO ₄ ⁻ and (DPPMH)₂Cr₂O ₇ ⁻ are extracted for tracer and macro amounts of chromium(VI) respectively. The data have been utilized for the separation of chromium(VI) from base metal ions.     

Extraction of triaquatrinitrorhodium form with calix[<Emphasis Type="Italic">n</Emphasis>]arenethiaethers from nitric acid nitrite–nitrate solutions

Comparison of extraction properties of macrocyclic calix[4,6]arenethiaethers (CATE) with their acyclic analogs R₂S (R = C₆H₁₃, C₈H₁₇) for the recovery of [Rh(NO₂)₃(H₂O)₃]⁰ rhodium form from nitric acid solutions was carried out. Rhodium recovery with CATE (0.05 M) in the absence of accelerating additives under optimal conditions exceeds 90% at 5–10-fold preconcentration and is only 1–3% for R₂S (1 M). Extraction kinetics was studied and hypothesis on the mechanism of multiple acceleration of rhodium recovery was proposed for CATE extraction, the mechanism includes the formation of intermediate product of colloidal- chemical nature on account of the surface activity of the macrocycle and its reaction with rhodium accompanied by rhodium chelation to the sulfur atoms of neighboring fragments of the macrocycle. The obtained results are of interest for the development of methods for the isolation of fission rhodium from nitrate–nitrite nitric acid solutions.     

Extraction of scandium(III) by bis(diphenylphosphorylmethylcarbamoyl)alkanes

The extraction of trace amounts of scandium(III) from HCl,HNO₃, and HClO₄ solutions in the form of complexes with neutral polyfunctional organophosphorus compounds bis(diphenylphosphorylmethylcarbamoyl)alkanes [Ph₂P(O)CH₂C(O)NH]₂(CH₂) _n (n = 3, 5, 8) was studied. The effect of the structure of the extractant, the aqueous phase composition, and the nature of the organic solvent on the efficiency of transition of scandium(III) ions into the organic phase was considered, and the stoichiometry of the extracted complexes was determined. The studied ligands exhibit a higher extraction power toward scandium(III) ions than their analog Ph₂P(O)CH₂C(O)NHC₉H₁₉ containing only one bidentate carbamoylmethylphosphoryl moiety per molecule. Scandium(III) passes into the organic phase most efficiently in the presence of HClO4 in the aqueous phase. It was shown that scandium(III) can be selectively recovered and preconcentrated by a complexing adsorbent obtained by noncovalent immobilization of bis(diphenylphosphorylmethylcarbamoyl)pentane on a macroporous polymer matrix.     

Radiofluorination of a Pre‐formed Gallium(III) Aza‐macrocyclic Complex: Towards Next‐Generation Positron Emission Tomography (PET) Imaging Agents

As part of a study to investigate the factors influencing the development of new, more effective metal‐complex‐based positron emission tomography (PET) imaging agents, the distorted octahedral complex, [GaCl(L)]?2 H₂O has been prepared by reaction of 1‐benzyl‐1,4,7‐triazacyclononane‐4,7‐dicarboxylic acid hydrochloride (H₂L?HCl) with Ga(NO₃)₃?9 H₂O, which is a convenient source of Ga^III for reactions in water. Spectroscopic and crystallographic data for [GaCl(L)]?2 H₂O are described, together with the crystal structure of [GaCl(L)]?MeCN. Fluorination of this complex by Cl^?/F^? exchange was achieved in high yield by treatment with KF in water at room temperature over 90 minutes, although the reaction was complete in approximately 30 minutes if heated to 80 °C, giving [GaF(L)]?2 H₂O in good yield. The same complex was obtained by hydrothermal synthesis from GaF₃?3 H₂O and Li₂L, and has been characterised by single‐crystal X‐ray analysis, IR, ¹H and ¹⁹F{¹H} NMR spectroscopy and ESI⁺ MS. Radiofluorination of the pre‐formed [GaCl(L)]?2 H₂O has been demonstrated on a 210 nanomolar scale in aqueous NaOAc at pH 4 by using carrier‐free ¹⁸F^?, leading to 60–70 % ¹⁸F‐incorporation after heating to 80 °C for 30 minutes. The resulting radioproduct was purified easily by using a solid‐phase extraction (SPE) cartridge, leading to 98–99 % radiochemical purity. The [Ga¹⁸F(L)] is stable for at least 90 minutes in 10 % EtOH/NaOAc solution at pH 6, but defluorinates over this time scale at pH of approximately 7.5 in phosphate buffered saline (PBS) or human serum albumin (HSA). The subtle role of the Group 13 metal ion and co‐ligand donor set in influencing the pH dependence of this system is discussed in the context of developing potential new imaging agents for PET.