Cobalt Reagents Research Articles

Tannic acid as a novel and green leaching reagent for cobalt and lithium recycling from spent lithium-ion batteries

Tannic acid–acetic acid is proposed as novel and green chemicals for cobalt and lithium recycling from spent lithium-ion batteries through a leaching process. The synergism of both acids was documented through batch and continuous studies. Tannic acid promotes cobalt dissolution by reducing insoluble Co3+ into soluble Co2+, while acetic acid is critical to improve the dissolution and stabilize the metals in the pregnant leach solution. Based on batch studies, the optimum conditions for metal recovery at room temperature are acetic acid 1 M, tannic acid 20 g/L, pulp density 20 g/L, and stirring speed 250 rpm (94% cobalt and 99% lithium recovery). The kinetic study shows that increasing temperature to 80 °C improves cobalt and lithium recovery from 65 to 90% (cobalt) and from 80 to 99% (lithium) within 4 h at sub-optimum condition (tannic acid 10 g/L). Kinetic modeling suggests the leaching process was endothermic, and high activation energy indicates a surface chemical process. For other metals, the pattern of manganese and nickel recovery trend follows the cobalt recovery trend. Copper recovery was negatively affected by tannic acid. Iron recovery was limited due to the weak acidic condition of pregnant leach solution, which is beneficial to improve leaching selectivity.

Facile Synthesis of an Efficient Ni–Fe–Co Based Oxygen Evolution Reaction Electrocatalyst

Electrolytic water splitting offers energy storage and conversion opportunities, yet the slow kinetics of the oxygen evolution reaction requires the incorporation of catalytic materials. Herein, we present a facile method for the synthesis of a low-cost Ni-Fe-Co material that efficiently catalyzes the oxygen evolution reaction. A mixed transition metal electrocatalyst was synthesized using a nickel-plated iron substrate and a low concentration cobalt reagent. The catalyst was able to achieve competitive current densities (>130 mA cm−2) and still exhibit a low overpotential of 0.30 V at the benchmark current density of 10 mA cm−2. The Ni-Fe-Co catalyst was stable and maintained its activity during 24 h of electrolysis in alkaline media. The catalyst was also stable when maintained in ambient conditions for 90 days. This is the first reported oxygen evolution reaction catalyst that exhibits these competitive characteristics and that was synthesized using an environmentally-conscious, one-step process that can be manufactured on an industrial scale.

Mechanism of Cobalt-Catalyzed Direct Aminocarbonylation of Unactivated Alkyl Electrophiles: Outer-Sphere Amine Substitution To Form Amide Bond

Experimentalists have recently achieved the first chemoselective aminocarbonylation of unactivated alkyl electrophiles, using the common cobalt reagent Co2(CO)8 as a catalyst. Here, we present a de...

P-S bond cleavage in reactions of thiophosphinidene-bridged dimolybdenum complexes with [Co2(CO)8] to give phosphinidene-bridged heterometallic derivatives.

The thiophosphinidene complex [Mo2Cp2(μ-κ(2):κ(1),η(6)-SPMes*)(CO)2] (Mes* = 2,4,6-C6H2(t)Bu3) reacted with [Co2(CO)8] at room temperature or below to give several of the following phosphinidene-bridged products, depending on reaction conditions: the MoCo complexes [CoMoCp(μ-κ(1):κ(1),η(6)-PMes*)(CO)3] and [CoMoCp(μ-PMes*)(CO)5] (Co-Mo = 2.972(1) Å), the MoCo3 cluster [Co3MoCp(μ3-PMes*)(CO)9] (Co-Mo = 2.664(1), 2.810(1) Å), and the sulphido-bridged tetranuclear complexes [Co2Mo2Cp2(μ-κ(1):κ(1):κ(1),η(4)-PMes*)(μ3-S)(CO)7] and [Co3MoCp(μ-κ(1):κ(1):κ(1),η(4)-PMes*)(μ3-S)(CO)8]. In contrast, the thiophosphinidene complex [Mo2Cp2(μ-κ(2):κ(1),η(4)-SPMes*)(CO)3] reacted with the same cobalt reagent selectively to give the above Mo2Co2 complex in very high yield. The latter could be decarbonylated photochemically to give [Co2Mo2Cp2(μ-κ(1):κ(1):κ(1),η(6)-PMes*)(μ3-S)(CO)6] (Co-Co = 2.435(3), Co-Mo = 2.769(2), 2.798(2) Å), after an η(4)- to η(6)-haptotropic rearrangement of the aryl ring of the phosphinidene ligand that could be reversed upon reaction with CO. The related complex [Mo2Cp2(μ-κ(2):κ(1),η(4)-SPMes*)(CO)2(CN(t)Bu)], however, displayed poor selectivity towards the cobalt dimer and yielded a mixture of CoMo complexes [CoMoCp(μ-PMes*)(CO)5] and [CoMoCp(μ-PMes*)(CO)3(CN(t)Bu)2], and the tetranuclear sulphido-bridged ones [Co2Mo2Cp2(μ-κ(1):κ(1):κ(1),η(4)-PMes*)(μ3-S)(CO)6(CN(t)Bu)] (Co-Co = 2.533(1), Co-Mo = 2.7485(9), 2.770(1) Å) and [Co3MoCp(μ-κ(1):κ(1):κ(1),η(4)-PMes*)(μ3-S)(CO)7(CN(t)Bu)] (Co-Co = 2.4120(7) to 2.5817(7) Å). This reduction in selectivity might have an electronic origin rather than a steric origin, since the related but cationic substrate [Mo2Cp2{μ-κ(2):κ(1),η(5)-SP(C6H3(t)Bu3)}(CO)2(CN(t)Bu)]BAr [Ar' = 3,5-C6H3(CF3)2] reacted with [Co2(CO)8] more selectively to give the sulphido-bridged Co2Mo2 complex [Co2Mo2Cp2{μ-κ(1):κ(1):κ(1),η(5)-P(C6H3(t)Bu3)}(μ3-S)(CO)6(CN(t)Bu)]BAr, along with small amounts of the Co3Mo complex [Co3MoCp{μ-κ(1):κ(1):κ(1),η(5)-P(C6H3(t)Bu3)}(μ3-S)(CO)7(CN(t)Bu)]BAr (Co-Co = 2.414(2) to 2.560(2) Å). The structure of the new complexes was analyzed on the basis of the corresponding X-ray diffraction and spectroscopic data, and likely reaction pathways were discussed on the basis of the above results and some additional experiments.

Evaluation study of cobalt(II) and strontium(II) sorption–desorption behavior for selection of soil remediation technology

Sorption–desorption properties of cobalt(II) and strontium(II) ions were studied using a soil sample from the vicinity of the Serbian radioactive waste processing and interim storage facilities. The mobility of the cations in the soil was evaluated and compared with the intention to facilitate the selection of optimal remediation strategy in case of accidental soil contamination with radioactive cobalt-60 and strontium-90 isotopes. A systematic sorption study was performed through a series of batch experiments at different aging times, cation concentrations and pH. Kinetics experiments revealed that sorbed amounts of cobalt(II) continuously increased with contact time until quasi-equilibrium was reached, while initial fast strontium(II) sorption was followed by a desorption step. Based on the shapes of the sorption isotherms and calculated sorption parameters, it was concluded that cobalt(II) sorbed more selectively and strongly than strontium(II). Sequential extraction showed that, regardless of the initial content of contaminants in the soil and the aging time, high amounts of both cations were bonded to relatively mobile fractions: strontium(II) in the exchangeable, while cobalt(II) in the carbonate and ferromanganese oxide fraction. Strontium(II) was readily desorbed in acidic, calcium(II) and ethylenediaminetetraacetic acid-containing media, whereas complexing agents such as citric and tartaric acids at low pH were more effective reagents for cobalt(II) desorption. The results from the present study indicate that chemical extraction can be considered as remediation option for strontium(II)- and cobalt(II)-contaminated soil.

ChemInform Abstract: Allylic Oxidations of Olefins to Enones

AbstractReview: 234 refs.

Allylic Oxidations of Olefins to Enones

Allylic oxidations of olefins to enones are C–H functionalizations and are valuable organic transformations that permit the synthesis of value-added products from simple precursors. A variety of stoichiometric and catalytic metal-based methods are available for these conversions. In addition, metal-free and biocatalytic protocols are gaining in importance. This review summarizes the available oxidation methods and compares their regio- and chemoselectivities. 1 Introduction 2 Chromium-Based Oxidation 2.1 Stoichiometric Methods 2.2 Catalytic Methods 2.3 Chromium on Solid Support 3 Regio- and Chemoselectivity of Allylic Oxidations 4 Other Metal-Based Oxidations 4.1 Copper Reagents 4.2 Rhodium Reagents 4.3 Selenium Reagents 4.4 Cobalt Reagents 4.5 Ruthenium Reagents 4.6 Palladium Reagents 4.7 Iron Reagents 4.8 Other Metal Reagents 5 Metal-Free and Biocatalytic Methods 5.1 Metal-Free Methods 5.2 Biocatalytic Methods 6 Conclusion

폐(廢)리튬이온전지(電池) 양극활물질(陽極活物質)에서 유기산(有機廳)을 이용(利用)한 코발트 및 리튬의 화학적(化學的) 침출(浸出)

페리튬이온전지 양극활물질인 <TEX>$LiCoO_2$</TEX>로부터 코발트와 리튬을 회수하기 위한 기초 연구로 환경친화적인 유기산을 이용하여 코발트와 리튬의 침출에 관한 연구를 실시하였다. 주요 실험 변수로는 유기산 종류 및 농도, 과산화수소 농도, 반응 시간 및 온도 그리고 고액농도비 등 코발트와 리튬의 침출에 영향을 미칠 수 있는 인자들에 대하여 고찰하여 최적 조건을 얻고자 하였다. 실험 결과 사용한 유기산중에서 Latic acid가 코발트 및 리튬의 침출율이 99.9%로 가장 우수 하였다. 한편, 구연산을 이용하여 창출 실험한 결과에서 과산화수소의 농도, citric acid의 농도 및 반응온도가 증가함에 따라 코발트 및 리튬의 침출율이 증가하였다. 그러나 고액농도비가 증가함에 따라 침출율은 감소하는 경향을 보였다. Environmental friendly leaching process for the recovery of cobalt and lithium from the <TEX>$LiCoO_2$</TEX> was investigated by organic acids as a leaching reagent. The experimental parameters, such as organic acid type, concentrations of leachant and hydrogen peroxide, reaction time and temperature as well as the pulp density were tested to obtain the most effective conditions for the leaching of cobalt and lithium. The results showed that the latic acid was the most effective leaching reagent for cobalt and lithium among the organic acids and was reached about 99.9% of leaching percentage respectively. With the increase of the concentration of citric acid, hydrogen peroxide and temperature, the leaching rate of cobalt and lithium increased. But the increase of pulp density decreased the leaching rate of cobalt and lithium.

Environmental friendly leaching reagent for cobalt and lithium recovery from spent lithium-ion batteries

We investigated an environmentally friendly leaching process for the recovery of cobalt and lithium from the cathode active materials of spent lithium-ion batteries. The easily degradable organic acid DL-malic acid (C 4H 5O 6) was used as a leaching reagent. The structural, morphology of the cathode materials before and after leaching were characterized by X-ray diffraction (XRD) and scanning electronic microscopy (SEM). The amount of Co and Li present in the leachate was determined by atomic absorption spectrophotometry (AAS). Conditions for achieving a recovery of more than 90 wt.% Co and nearly 100 wt.% Li were determined experimentally by varying the concentrations of leachant, time and temperature of the reaction as well as the initial solid-to-liquid ratio. We found that hydrogen peroxide in a DL-malic acid solution is an effective reducing agent because it enhances the leaching efficiency. Leaching with 1.5 M DL-malic acid, 2.0 vol.% hydrogen peroxide and a S:L of 20 g L −1 in a batch extractor results in a highly efficient recovery of the metals within 40 min at 90 °C.

Synthesis, Properties and Formation of (RCp)Co‐ and (RCp)Rh‐Stabilized[4.8]3Cyclacene Derivatives

Metal-stabilized belts: A torus, 3, consisting of three four- and three eight-membered conjugated rings and stabilized by (RCp)Co- and (RCp)Rh- units, was generated by irradiation of [(RCp)Co(CO)(2)] and [(RCp)Rh(C(2)H(4))(2)], respectively, and 1.Eleven metal stabilized [4.8](3)cyclacene derivatives were synthesized. The substances were prepared in one-pot reactions by irradiation of a solution of 5,6,11,12-tetradehydro-dibenzo[a,e]cyclooctatetraene and the corresponding cobalt reagents or rhodium compounds. The resulting cyclacene derivatives reveal D(3h) symmetry in solution. In the solid state the hoop shaped systems crystallize in layers, which are intercalated with solvent layers. To unravel the mechanism of the one-pot reaction we isolated an intermediate, which shows almost planar cyclooctatetraene rings.

Synthesis and Reactivity of 10- and 12-Vertex Cobalt−Monocarborane Anions Containing Multiple Metal Centers

Treatment of [closo-1-CB7H8]- with [Co2(CO)8] in THF at room temperature affords the 10-vertex dicobalt−monocarbollide anion [6,10-(μ-CO)-6,6,10,10-(CO)4-closo-6,10,1-Co2CB7H8]-, isolated as the [N(PPh3)2]+ salt (6). The analogous 12-vertex species [N(PPh3)2][2,3-(μ-CO)-2,2,3,3-(CO)4-closo-2,3,1-Co2CB9H10] (7) is obtained similarly from [arachno-6-CB9H14]- and [Co2(CO)8] heated to 50 °C. Both 6 and 7 contain a cobalt−cobalt bond that is bridged by one CO ligand. In contrast, the same cobalt reagent with [closo-4-CB8H9]- at room temperature gives the tricobalt species [6,7,10-{Co2(μ-CO)(CO)5}-7-(μ-H)-6,6-(CO)2-closo-6,1-CoCB8H7]-, similarly isolated as its [N(PPh3)2]+ salt (8a). The latter contains a V-shaped tricobalt unit, part of a {Co3B} butterfly that is edge-fused to a {CoCB8} cluster. Compounds 6 and 7 with CF3SO3Me in CH2Cl2−THF (1:1) give the zwitterionic, B-substituted complexes [6,10-(μ-CO)-6,6,10,10-(CO)4-8-{O(CH2)4}-closo-6,10,1-Co2CB7H7] (9) and [2,3-(μ-CO)-2,2,3,3-(CO)4-12-{O(CH2)4}-closo-2,...

Probing Nucleic Acid Structure with Nickel‐ and Cobalt‐Based Reagents

The use of nickel and cobalt reagents is presented for characterizing the solvent exposure of guanine residues in DNA and RNA. These reagents promote guanine oxidation in the presence of a peracid such as monopersulfate, and the extent of reaction indicates the steric and electronic environment surrounding the N7 and aromatic face of this residue. Since oxidation does not itself perturb target structure or induce strand scission, it is coupled with fragmentation by treatment with piperidine (for smaller polynucleotides) or termination of primer extension (for larger polynucleotides).

Nickel and cobalt reagents promote selective oxidation of Z-DNA.

The structural characteristics of Z-DNA were used to challenge the selectivity of guanine oxidation promoted by nickel and cobalt reagents. Base pairing and stacking within all helical structures studied previously had hindered access to guanine and limited its reaction. However, the Z-helix uniquely retains high exposure of guanine N7. This exposure was sufficient to direct oxidation specifically to a plasmid insert -(CG)(13)AATT(CG)(13)- that adopted a Z-conformation under native supercoiling. An alternative insert -(CG)(7)- retained its B-conformation and demonstrated the expected lack of reactivity. For a nickel salen complex made from a particularly bulky ligand, preferential reaction shifted to the junctions within the Z-DNA insert as is common for large reagents. Inactivation of the nickel reagents by high-salt concentrations prevented parallel investigations of Z-DNA, formed by oligonucleotides. However, the activity of Co(2+) was minimally affected by salt and consequently confirmed the high reactivity of 5'-p(CG)(4) in its Z-conformation. These reagents may now be applied to a broad array of targets, since their structural specificity remains predictable for both complex and helical assemblies of nucleic acids.

The synthesis and applications of a new chromogenic and fluorescence reagent for cobalt(II)

A new reagent, 5-(4-arsonicphenylazo)-8-(4-toluenesulfonamido)quinoline (APTSQ), was synthesised and its reaction with cobalt(II) and other metal ions was investigated. APTSQ was found to be a sensitive and selective reagent for the spectrophotometric and fluorimetric determination of trace amounts of cobalt. In the presence of cetyltrimethylammonium bromide, Co(II) reacts with APTSQ in basic medium to form a blue–violet complex in a molar ratio of 1:3. The maximum absorbance of the complex is at 582 nm with a molar absorptivity of 1.18×105 l mol–1 cm–1. Beer’s law is obeyed for cobalt concentrations in the range 0–0.5 µg ml–1. The interference of 34 substances was examined. In the presence of H2O2, cobalt reacts with APTSQ in solutions above pH 8.7, forming a product which shows intense fluorescence with λex at 229, 287 and 331 nm and λem at 376 nm. The fluorescence intensity is proportional to concentration of cobalt in the range of 0–25 ng ml–1. A detection limit (S/N = 3) of 0.002 ng ml–1 was obtained. The mechanism of the fluorescence reaction was also investigated. The two proposed methods are precise, sensitive and simple and were applied to the determination of trace amounts of cobalt in mixtures, vitamin B12 and vegetable samples.

Comparative studies on the generation and cyclisation reactions of difluoroalkyl radicals

Treatment of a series of unsaturated bromodifluoromethyl malonate precursors using organotin, samarium, and cobalt reagents as radical triggers leads to the formation of usefully functionalised fluorinated cyclopentanoid products.

2,7 -Dichloroquinoline-3-carbaldehyde Thiosemicarbazone as an Analytical Reagent for Cobalt(II) and Copper(II)

2,7 -Dichloroquinoline-3-carbaldehyde Thiosemicarbazone as an Analytical Reagent for Cobalt(II) and Copper(II)

8-Methoxy-2-chloroquinoline-3-carbaldehyde Thiosemicarbazone as an Analytical Reagent for Cobalt(II) and Copper(II)

8-Methoxy-2-chloroquinoline-3-carbaldehyde Thiosemicarbazone as an Analytical Reagent for Cobalt(II) and Copper(II)

Progressive transmetalation of tetranuclear dioxocopper(II) complexes with cobalt reagents

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTProgressive transmetalation of tetranuclear dioxocopper(II) complexes with cobalt reagentsMaher Henary, Geoffrey Davies, Atieh Abu-Raqabah, Mohamed A. El-Sayed, and Ahmed El-ToukhyCite this: Inorg. Chem. 1988, 27, 11, 1872–1879Publication Date (Print):June 1, 1988Publication History Published online1 May 2002Published inissue 1 June 1988https://doi.org/10.1021/ic00284a013RIGHTS & PERMISSIONSArticle Views65Altmetric-Citations7LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (821 KB) Get e-Alerts Get e-Alerts

ChemInform Abstract: Novel Reactions of the Low Valent Cobalt Reagent Generated Using CoCl2 and NaBH4/C2H5OH in the Presence of Carbon Monoxide.

AbstractReaction of the terminal olefin (I) with sodium boranate, CoCl2 (II), and carbon monoxide (III) proceeds via the complex (IV) which yields either the alkane (V) or the rearranged E‐alkene (VI) depending on the method of work‐up.

Novel reactions of the low valent cobalt reagent generated using CoCl 2 and NaBH 4/C 2H 5OH in the presence of carbon monoxide

Low valent cobalt species, prepared in situ in tetrahydrofuran (THF) by the reduction of CoCl 2 with NaBH 4/C 2H 5OH under carbon monoxide, isomerize of alkenes, reduce alkenes, and carbonylate benzyl halides under appropriate conditions.