Recent Advances in the Chemistry of SmI2–H2O

Sautier, Brice; Procter, David J.

doi:10.2533/chimia.2012.399

Cited by 30 publications

(10 citation statements)

References 14 publications

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“…The (4) high molecularity of the empirical rate law which is second order in water and the large degree of order in the activated complex are consistent with the transition state shown below in Scheme 4. If the electron and proton transfer were successive processes, an expression cannot be derived that fits the experimentally determined data.…”

Section: 18supporting

confidence: 80%

“…These substrates were chosen since they are known to be reduced by Sm-water systems 4 and studies would not be complicated by competition with water for coordination sites on Sm(II) since both are reduced through predominantly an outer-sphere process. To this end we chose two classes of substrates, an arene (anthracene) and a primary alkyl iodide (1-iodododecane).…”

Section: Resultsmentioning

confidence: 99%

“…2 In each case, the effectiveness of the approach is dependent on proton donor concentration, competition for Sm(II) coordination between substrate and proton donor and other reaction components. 4 The seminal work of Curran and Hasegawa demonstrated that water addition to SmI 2 accelerated the rate of functional group reduction and they proposed that the effectiveness of the reducing system was a consequence of water coordination to Sm(II). Given this, proton donors employed in reactions of SmI 2 are distinguished by those which have a high affinity for Sm(II) (water, methanol, glycols) and those that do not (phenol, 2,2,2,-trifluoroethanol, t-butanol, etc.).…”

Section: Introductionmentioning

confidence: 99%

“…3 Among Sm(II)-proton donor systems, those that employ water or coordinating proton donors are the most effective at reducing substrates typically recalcitrant to reduction through electron transfer. 4 The seminal work of Curran and Hasegawa demonstrated that water addition to SmI 2 accelerated the rate of functional group reduction, and they proposed that the effectiveness of the reducing system was a consequence of water coordination to Sm(II). 5 This hypothesis was later confirmed by the groups of Hoz and Flowers.…”

Section: ■ Introductionmentioning

confidence: 99%

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Proton-Coupled Electron Transfer in the Reduction of Arenes by SmI₂–Water Complexes

Chciuk

Flowers

2015

J. Am. Chem. Soc.

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The presence of water has a significant impact on the reduction of substrates by SmI2. The reactivity of the Sm(II)-water reducing system and the relationship between sequential or concerted electron-transfer, proton-transfer is not well understood. In this work, we demonstrate that the reduction of an arene by SmI2-water proceeds through an initial proton-coupled electron transfer. The use of thermochemical data available in the literature shows that upon coordination of water to Sm(II) in THF, significant weakening of the O-H bond occurs. The derived value of nearly 73 kcal/mol for the decrease in the bond dissociation energy of the O-H bond in the Sm(II)-water complex is the largest reported to date for low-valent reductants containing bound water.

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Section: 18supporting

confidence: 80%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: ■ Introductionmentioning

confidence: 99%

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Proton-Coupled Electron Transfer in the Reduction of Arenes by SmI₂–Water Complexes

Chciuk

Flowers

2015

J. Am. Chem. Soc.

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“…Due to these developments, there has been an increasing demand for this metal [3], yet there are limited commercially exploitable reserves [1,4,5]. Scandium is widely dispersed in the Earth's crust [5,6] at a concentration of about 22 ppm, comparable to that of cobalt and greater than that of lead and other common metals [7]. Currently, there is no scandium production in Europe and production occurs in China (66%), Russia (26%) and Ukraine (7%) [8].…”

Section: Introductionmentioning

confidence: 99%

Recovery of Scandium by Crystallization Techniques

Peters

Kaya

Dittrich

et al. 2019

J. Sustain. Metall.

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Bauxite residues, i.e., red mud, can be processed to recover various valuable end products, while reducing the environmental impact of the waste. Scandium is one of the valuable elements in bauxite residues. It is possible to extract and enrich scandium from red mud by leaching and solvent extraction. Scandium can then be recovered from the pregnant strip liquor by crystallization. Different crystallization techniques can be used to generate the supersaturation required for scandium to crystallize out as a salt. In the present study, the crystallization of an ammonium scandium fluoride phase by cooling and antisolvent crystallization techniques is presented. Cooling crystallization gave a low yield of ammonium scandium hexafluoride, (NH 4) 3 ScF 6 , below 50% at the lowest temperature of 1 °C investigated. Antisolvent crystallization using ethanol gave almost complete recovery with precipitation efficiency greater than 98% for an ethanol-to-strip liquor volumetric ratio of 0.8. Solubility data of (NH 4) 3 ScF 6 under different temperatures and in different ethanol-strip liquor mixtures is herein presented. The product obtained by antisolvent crystallization had very minute crystals (< 2 µm) due to the high supersaturation generated upon adding ethanol to the strip liquor, while it was easier to obtain larger crystals by cooling crystallization. Fe and Ti impurities were detected in the solid product, and an insight into the mechanism of impurity uptake is discussed.

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Radical Cascade Reaction in Heterocyclic Synthesis: Formation of Bicyclic 2,3‐dihydrostannoles and Other Heterocyclic Compounds from Amide‐type 1,6‐Enyne Compounds

Kamimura,

Kohno,

Ishido

et al. 2023

Asian J Org Chem

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Amide-type 1,6-enyne compounds, readily available from unsaturated N-Boc acyl amide and propargylic mesylate, underwent a radical cascade reaction upon treatment with Bu 3 SnH, giving bicyclic 2,3-dihydrostannole lactams in good yields. Regioselectivity of the reaction depended on the presence or absence of alkyne substituents; alkyl-substituted internal alkynes selectively gave 2,3-dihydrostannoles in good yields, while terminal alkynes gave a mixture of piperidine and 2,3-dihydrostannole. The reaction promoted the radical cascade process starting from the addition of tin radical to the alkenyl terminal followed by 5-exo-dig radical cyclization. The resulting vinyl radical attack the tin atom, and direct radical substitution progressed, giving bicyclic 2,3dihydrostannoles in good yields.

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Recent Advances in the Chemistry of SmI2–H2O

Cited by 30 publications

References 14 publications

Proton-Coupled Electron Transfer in the Reduction of Arenes by SmI₂–Water Complexes

Proton-Coupled Electron Transfer in the Reduction of Arenes by SmI₂–Water Complexes

Recovery of Scandium by Crystallization Techniques

Radical Cascade Reaction in Heterocyclic Synthesis: Formation of Bicyclic 2,3‐dihydrostannoles and Other Heterocyclic Compounds from Amide‐type 1,6‐Enyne Compounds

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Recent Advances in the Chemistry of SmI2–H2O

Cited by 30 publications

References 14 publications

Proton-Coupled Electron Transfer in the Reduction of Arenes by SmI2–Water Complexes

Proton-Coupled Electron Transfer in the Reduction of Arenes by SmI2–Water Complexes

Recovery of Scandium by Crystallization Techniques

Radical Cascade Reaction in Heterocyclic Synthesis: Formation of Bicyclic 2,3‐dihydrostannoles and Other Heterocyclic Compounds from Amide‐type 1,6‐Enyne Compounds

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Product

Resources

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Proton-Coupled Electron Transfer in the Reduction of Arenes by SmI₂–Water Complexes

Proton-Coupled Electron Transfer in the Reduction of Arenes by SmI₂–Water Complexes