Radiolysis of solvents containing C5-BTBP: identification of degradation products and their dependence on absorbed dose and dose rate

Fermvik, Anna; Berthon, Laurence; Ekberg, Christian; Englund, Sofie; Retegan, Teodora; Zorz, Nicole

doi:10.1039/b907084b

Cited by 36 publications

(57 citation statements)

References 22 publications

(22 reference statements)

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“…Heating 1 to 75°C in 15.5819 (7) 16.733 (1) 16.830 (1) 13.3034(7) b (Å) 11.1657 (5) 17.651 (1) 10.0546 (6) 17.3503(9) c (Å) 17.3224 (7) 17.077 (1) 103 (2) 88 (2) 173 (2) 143 (2) 143 (2) the presence of excess TEMPO also gave only 1 as the product. 1 H NMR spectroscopy revealed resonances consistent with Me-TEMPO as a byproduct. Complex 1 was definitively identified by X-ray crystallography, which revealed that it is an (η 1 -TEMPO) − complex (Figure 1).…”

Section: ■ Introductionmentioning

confidence: 88%

“…Colorless X-ray-quality crystals of 1 were grown from a hexane solution at −30°C (140 mg, 60%). 1 H NMR (C 6 D 6 ): δ 2.08 (s, 30H, C 5 Me 5 ), 1.39 (m, 4H, ONC 5 H 6 Me 4 ), 1.24 (m, 2H, ONC 5 H 6 Me 4 ), 1.14 (s, 12H, ONC 5 H 6 Me 4 ), 0.43 (s, 3H, Me). 13 (η 5 -C 5 Me 5 ) 2 Th(η 1 -C 3 H 5 )(η 3 -C 3 H 5 ) (2).…”

Section: ■ Introductionmentioning

confidence: 99%

“…Colorless X-ray-quality crystals of 6 were grown from a toluene solution at −25°C. 1 (η 2 -TEMPO) 2 ThBr 2 (7). In a glovebox containing coordinating solvents such as THF, a red solution of TEMPO (95 mg, 0.61 mmol) in toluene (3 mL) was slowly added by pipet to a stirred colorless solution of (η 5 -C 5 Me 5 ) 2 ThBr 2 (200 mg, 0.302 mmol) in toluene (18 mL).…”

Section: ■ Introductionmentioning

confidence: 99%

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Reactivity of Organothorium Complexes with TEMPO

2014

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Reactions of the 2,2,6,6-tetramethylpiperidin-1-oxyl radical (TEMPO) with thorium metallocenes have been examined to investigate both the radical reaction patterns for organothorium complexes and the coordination chemistry of TEMPO with thorium. (η(5)-C5Me5)2ThMe2 reacts with 2 equiv of TEMPO to generate 1-methoxy-2,2,6,6-tetramethylpiperidine (Me-TEMPO) and (η(5)-C5Me5)2ThMe(η(1)-TEMPO), which contains a TEMPO(-) anion coordinated to thorium through oxygen only. (η(5)-C5Me5)2Th(η(1)-C3H5)(η(3)-C3H5), synthesized from (η(5)-C5Me5)2ThBr2 and (C3H5)MgBr, reacts with 2 equiv of TEMPO to form 1-(2-propen-1-yloxy)-2,2,6,6-tetramethylpiperidine (allyl-TEMPO) and (η(5)-C5Me5)2Th(η(1)-C3H5)(η(1)-TEMPO). Although bis(TEMPO) metallocenes were not obtained in these reactions, the methyl group in (η(5)-C5Me5)2ThMe(η(1)-TEMPO) is reactive with 1 equiv of CuBr to form (η(5)-C5Me5)2ThBr(η(1)-TEMPO). The bis(TEMPO) metallocene (η(5)-C5Me5)2Th(η(1)-TEMPO)2 is accessible in the reaction of [(η(5)-C5Me5)2ThH2]2 with 4 equiv of TEMPO. In contrast, (η(5)-C5Me5)2ThBr2 reacts with 2 equiv of TEMPO by loss of C5Me5 to form (C5Me5)2 and (η(2)-TEMPO)2ThBr2, in which the TEMPO(-) anions bind through oxygen and nitrogen. The bromide ions in (η(2)-TEMPO)2ThBr2 can be replaced by an additional 2 equiv of TEMPO in the presence of 2 equiv of KC8 to form the per(TEMPO) complex Th(η(1)-TEMPO)2(η(2)-TEMPO)2. ThBr4(THF)4 reacts with TEMPO to form ThBr4(THF)2(η(1)-TEMPO), which contains an oxygen-bound TEMPO radical. The Th(3+) complex (η(5)-C5Me4H)3Th is oxidized in the presence of TEMPO, without ligand loss, to afford the Th(4+) species (η(5)-C5Me4H)3Th(η(1)-TEMPO). The reactions show that TEMPO can react with organothorium complexes in several ways including coordination, anion substitution, and cyclopentadienyl replacement.

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Section: ■ Introductionmentioning

confidence: 88%

Section: ■ Introductionmentioning

confidence: 99%

Section: ■ Introductionmentioning

confidence: 99%

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Reactivity of Organothorium Complexes with TEMPO

2014

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“…As a solvent containing C5-BTBP received gradually increasing doses, the extraction of both actinides and lanthanides decreased substantially, making the molecule useless in a potential process. However, the radiolytic behavior of C5-BTBP containing solvents is interesting and has been further studied [4][5][6][7]. The extraction of americium (analogue for trivalent actinides) decreased more than the extraction of europium (analogue for trivalent lanthanides), resulting in a decrease of the separation factor [4,6].…”

Section: Introductionmentioning

confidence: 99%

Semi-quantitative and quantitative studies on the gamma radiolysis of C5-BTBP

Fermvik¹,

Grüner

Kvı́čalová

et al. 2011

Radiochimica Acta

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An industrial liquid-liquid extraction process for reprocessing of spent nuclear fuel will inevitably lead to radiolysis of the phases, since the process streams contain highly radioactive species. Solvents containing one of the BTBP (6,6 -bis(5,6-dialkyl-[1,2,4]-triazin-3-yl)-2,2 -bipyridine) molecules intended for the separation of trivalent actinides (An) from lanthanides (Ln), the so called C5-BTBP, have shown a dramatic decrease in both distribution ratios and An/Ln separation factor when irradiated; hence, the molecule is highly unstable towards radiolysis.HPLC-, APCI(+)-MS and LC-MS analyses were performed on irradiated solvents containing initially 0.005 M C5-BTBP dissolved in either hexanol or cyclohexanone. The decrease in concentration of starting molecule as well as the increase in concentration of various degradation products were studied with quantitative and semi-quantitative measurements. Structures were suggested for the degradation products produced in highest yields and these were compared to previously proposed structures for the same products.

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“…However, the 6,6'-bis(5,6-dialkyl-1,2,4-triazin-3-yl)-2,2'-bipyridines (Cn-BTBPs, n = 1-5) were subjected to both acidic hydrolysis and radiolytic degradation by removal of their labile benzylic hydrogen atoms by free-radical species. [39] This led to the development of 6,6'-bis (5,5,8,8-tetramethyl-5,6,7,8-tetrahydro-1,2,4-benzotriazin-3-yl)-2,2-bipyridine (CyMe 4 -BTBP) 3 ( Figure 1) in which the benzylic hydrogens have been removed. [40] To date this ligand is the most promising for use in a future SANEX process and in a counter-current 'hot-test' using laboratory centrifugal contactors, 99.9 % of the actinides were removed from the feed solution in a 16-stage flowsheet with very high decontamination factors for Am (7,000) and Cm (1,000).…”

Section: Introductionmentioning

confidence: 99%

The Separation of Americium(III) from Europium(III) by Two New 6,6'-Bistriazinyl-2,2'-Bipyridines in Different Diluents

Harwood

Lewis

Hudson

et al. 2011

Solvent Extraction and Ion Exchange

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The synthesis and extraction of americium(III) and europium(III) from aqueous nitric acid solutions by the new BTBP ligands 6,6'-bis (5,5,7,7-tetramethyl-5,7-dihydrofuro[3,4-e]-1,2,4-triazin-3-yl)-2,2'-bipyridine (Cy 5 -O-Me 4 -BTBP) and 6,6'-bis (5,5,7,7-tetramethyl-5,7-dihydrothieno[3,4-e]-1,2,4-triazin-3-yl)-2,2'-bipyridine (Cy 5 -S-Me 4 -BTBP) is described. The affinity for Am(III) and the selectivity for Am(III) over Eu(III) of Cy 5 -S-Me 4 -BTBP were generally higher than for Cy 5 -O-Me 4 -BTBP. For both ligands, the extraction of Am(III) and Eu(III) from 3 M HNO 3 into 3 mM organic solutions varied with the diluent used. The highest distribution ratios and separation factors observed were in cyclohexanone and 2-methylcyclohexanone, respectively. For Cy 5 -S-Me 4 -BTBP, there is a strong correlation between the distribution ratio for Am(III) and the permittivity of the diluent used. With 1-octanol as the diluent, low distribution ratios (D(Am) < 1) were observed for Cy 5 -S-Me 4 -BTBP although this ligand extracts Am(III) selectively (SF Am/Eu = 16-46 from 1-4 M HNO 3 ). For Cy 5 -S-Me 4 -BTBP, Am(III) is extracted as the disolvate. The distribution ratios for Am(III), and the separation factors for Am(III) over Eu(III) are both significantly higher for CyMe 4 -BTBP than they are for Cy 5 -O-Me 4 -BTBP and Cy 5 -S-Me 4 -BTBP in cyclohexanone. Changing the diluent from cyclohexanone to 2-methylcyclohexanone leads to a decrease in D(Am) but an increase in SF Am/Eu for Cy 5 -S-Me 4 -BTBP.

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Radiolysis of solvents containing C5-BTBP: identification of degradation products and their dependence on absorbed dose and dose rate

Cited by 36 publications

References 22 publications

Reactivity of Organothorium Complexes with TEMPO

Reactivity of Organothorium Complexes with TEMPO

Semi-quantitative and quantitative studies on the gamma radiolysis of C5-BTBP

The Separation of Americium(III) from Europium(III) by Two New 6,6'-Bistriazinyl-2,2'-Bipyridines in Different Diluents

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