1
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Petrus R, Kowaliński A, Lis T. Recycling primary lithium batteries using a coordination chemistry approach: recovery of lithium and manganese residues in the form of industrially important materials. Dalton Trans 2024; 53:7450-7469. [PMID: 38592737 DOI: 10.1039/d4dt00648h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/10/2024]
Abstract
In this study, we have investigated the potential use of post-consumer primary lithium metal batteries (LMBs) commonly used in portable electronic devices to recover lithium and manganese in the form of industrially important materials. A direct reaction of lithium-containing electronic waste with a naturally sourced ester, methyl salicylate, combined with a wide range of aliphatic alcohols has been used as a general method for recovering lithium in the form of lithium aryloxides of different nuclearities [Li(OAr)(HOMe)2] (1), [Li(OAr)(HOAr)] (2), [Li(OAr)(HOEt)]2 (3), [Li(OAr)(H2O)]2 (4), [Li4(OAr)4(EGME)2] (5), [Li6(OAr)6] (6-8) for ArOH = methyl salicylate (1, 2, 4, 6), ethyl salicylate (3, 7), 2-methoxyethyl salicylate (5, 8), and EGME = 2-methoxyethanol. The hydrolysis of 7 was then used to synthesize lithium salicylate [Li(Sal)(H2O)]n (10), which is an important antioxidant in the production of oils and grease. The discharged cathode material of Li-MnO2 batteries was investigated as a source from which LiClO4, Li2CO3, LiMn2O4, and Mn2O3 can be recovered by means of water-alcohol extraction or calcination. Particular emphasis was placed on the detailed characterization of all battery components and their decomposition products. LMBs were completely recycled for the first time, and materials were recovered from the cathode and the anode.
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Affiliation(s)
- Rafał Petrus
- Faculty of Chemistry, Wrocław University of Science and Technology, 23 Smoluchowskiego, 50-370 Wrocław, Poland.
| | - Adrian Kowaliński
- Faculty of Chemistry, Wrocław University of Science and Technology, 23 Smoluchowskiego, 50-370 Wrocław, Poland.
| | - Tadeusz Lis
- Faculty of Chemistry, University of Wrocław, 14 F. Joliot-Curie, 50-383 Wrocław, Poland
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2
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Lui NM, MacMillan SN, Collum DB. Lithiated Oppolzer Enolates: Solution Structures, Mechanism of Alkylation, and Origin of Stereoselectivity. J Am Chem Soc 2022; 144:23379-23395. [PMID: 36534055 PMCID: PMC10071589 DOI: 10.1021/jacs.2c09341] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Camphorsultam-based lithium enolates referred to colloquially as Oppolzer enolates are examined spectroscopically, crystallographically, kinetically, and computationally to ascertain the mechanism of alkylation and the origin of the stereoselectivity. Solvent- and substrate-dependent structures include tetramers for alkyl-substituted enolates in toluene, unsymmetric dimers for aryl-substituted enolates in toluene, substrate-independent symmetric dimers in THF and THF/toluene mixtures, HMPA-bridged trisolvated dimers at low HMPA concentrations, and disolvated monomers for the aryl-substituted enolates at elevated HMPA concentrations. Extensive analyses of the stereochemistry of aggregation are included. Rate studies for reaction with allyl bromide implicate an HMPA-solvated ion pair with a +Li(HMPA)4 counterion. Dependencies on toluene and THF are attributed to exclusively secondary-shell (medium) effects. Aided by density functional theory (DFT) computations, a stereochemical model is presented in which neither chelates nor the lithium gegenion serves roles. The stereoselectivity stems from the chirality within the sultam ring and not the camphor skeletal core.
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Affiliation(s)
- Nathan M Lui
- Department of Chemistry and Chemical Biology Baker Laboratory, Cornell University Ithaca, New York 14853-1301, United States
| | - Samantha N MacMillan
- Department of Chemistry and Chemical Biology Baker Laboratory, Cornell University Ithaca, New York 14853-1301, United States
| | - David B Collum
- Department of Chemistry and Chemical Biology Baker Laboratory, Cornell University Ithaca, New York 14853-1301, United States
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3
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Houghton MJ, Collum DB. Lithium Enolates Derived from Weinreb Amides: Insights into Five-Membered Chelate Rings. J Org Chem 2016; 81:11057-11064. [PMID: 27749060 PMCID: PMC5261255 DOI: 10.1021/acs.joc.6b02067] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Enolization of O-methyl hydroxamic acids (Weinreb amides) in tetrahydrofuran solution with lithium diisopropylamide affords predominantly tetrameric enolates. Aryl substituents on the enolates promote deaggregation. The aggregation states are assigned by using the method of continuous variation in conjunction with 6Li NMR spectroscopy. Decoalescence of the tetramer resonance below -100 °C shows considerable spectral complexity attributed to isomerism of the methoxy-based chelates. Density functional theory calculations were used to examine the consequences of the bite angle of five-membered chelates in cubic tetramers and resulting solvation numbers that were higher than anticipated.
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Affiliation(s)
- Michael J. Houghton
- Department of Chemistry and Chemical Biology, Baker Laboratory, Cornell University, Ithaca, New York 14853-1301
| | - David B. Collum
- Department of Chemistry and Chemical Biology, Baker Laboratory, Cornell University, Ithaca, New York 14853-1301
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4
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Abstract
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In
this paper, we investigate the coassembly of peptides derived
from the central and C-terminal regions of the β-amyloid peptide
(Aβ). In the preceding paper, J. Am. Chem. Soc.2016, DOI: 10.1021/jacs.6b06000, we established that peptides containing residues 17–23 (LVFFAED)
from the central region of Aβ and residues 30–36 (AIIGLMV)
from the C-terminal region of Aβ assemble to form homotetramers
consisting of two hydrogen-bonded dimers. Here, we mix these tetramer-forming
peptides and determine how they coassemble. Incorporation of a single 15N isotopic label into each peptide provides a spectroscopic
probe with which to elucidate the coassembly of the peptides by 1H,15N HSQC. Job’s method of continuous variation
and nonlinear least-squares fitting reveal that the peptides form
a mixture of heterotetramers in 3:1, 2:2, and 1:3 stoichiometries,
in addition to the homotetramers. These studies also establish the
relative stability of each tetramer and show that the 2:2 heterotetramer
predominates. 15N-Edited NOESY shows the 2:2 heterotetramer
comprises two different homodimers, rather than two heterodimers.
The peptides within the heterotetramer segregate in forming the homodimer
subunits, but the two homodimers coassemble in forming the heterotetramer.
These studies show that the central and C-terminal regions of Aβ
can preferentially segregate within β-sheets and that the resulting
segregated β-sheets can further coassemble.
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Affiliation(s)
- Nicholas L Truex
- Department of Chemistry, University of California, Irvine , Irvine, California 92697-2025, United States
| | - James S Nowick
- Department of Chemistry, University of California, Irvine , Irvine, California 92697-2025, United States
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5
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McNeil AJ. My maize and blue brick road to physical organic chemistry in materials. Beilstein J Org Chem 2016; 12:229-38. [PMID: 26977181 PMCID: PMC4778497 DOI: 10.3762/bjoc.12.24] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2015] [Accepted: 02/01/2016] [Indexed: 11/23/2022] Open
Abstract
Similar to Dorothy’s journey along the yellow brick road in The Wizard of Oz, this perspective carves out the path I took from my early childhood fascinations with science through my independent career at the University of Michigan (maize and blue). The influential research projects and mentors are highlighted, including some fortuitous experimental results that drew me into the field of supramolecular chemistry, specifically, and organic materials, broadly. My research group’s efforts toward designing new sensors based on small molecule gelators are described. In particular, I highlight how our design strategy has evolved as we learn more about molecular gelators. This perspective concludes with some predictions about where molecular gels, as well as my personal and professional life, are headed.
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Affiliation(s)
- Anne J McNeil
- Department of Chemistry and Macromolecular Science and Engineering Program, University of Michigan, 930 North University Avenue, Ann Arbor, Michigan 48109-1055, United States
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6
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Renny JS, Tomasevich LL, Tallmadge EH, Collum DB. Method of continuous variations: applications of job plots to the study of molecular associations in organometallic chemistry. Angew Chem Int Ed Engl 2013; 52:11998-2013. [PMID: 24166797 PMCID: PMC4028694 DOI: 10.1002/anie.201304157] [Citation(s) in RCA: 434] [Impact Index Per Article: 39.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2013] [Indexed: 11/10/2022]
Abstract
Applications of the method of continuous variations (MCV or the Method of Job) to problems of interest to organometallic chemists are described. MCV provides qualitative and quantitative insights into the stoichiometries underlying association of m molecules of A and n molecules of B to form A(m)B(n) . Applications to complex ensembles probe associations that form metal clusters and aggregates. Job plots in which reaction rates are monitored provide relative stoichiometries in rate-limiting transition structures. In a specialized variant, ligand- or solvent-dependent reaction rates are dissected into contributions in both the ground states and transition states, which affords insights into the full reaction coordinate from a single Job plot. Gaps in the literature are identified and critiqued.
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Affiliation(s)
- Joseph S. Renny
- Contribution from the Department of Chemistry and Chemical Biology Baker Laboratory, Cornell University, Ithaca, New York 14853-1301
| | - Laura L. Tomasevich
- Contribution from the Department of Chemistry and Chemical Biology Baker Laboratory, Cornell University, Ithaca, New York 14853-1301
| | - Evan H. Tallmadge
- Contribution from the Department of Chemistry and Chemical Biology Baker Laboratory, Cornell University, Ithaca, New York 14853-1301
| | - David B. Collum
- Contribution from the Department of Chemistry and Chemical Biology Baker Laboratory, Cornell University, Ithaca, New York 14853-1301
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7
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Renny JS, Tomasevich LL, Tallmadge EH, Collum DB. Methode der kontinuierlichen Variation: Verwendung von Job-Plots zur Untersuchung molekularer Assoziationen in der metallorganischen Chemie. Angew Chem Int Ed Engl 2013. [DOI: 10.1002/ange.201304157] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
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8
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Harrison-Marchand A, Mongin F. Mixed AggregAte (MAA): A Single Concept for All Dipolar Organometallic Aggregates. 1. Structural Data. Chem Rev 2013; 113:7470-562. [DOI: 10.1021/cr300295w] [Citation(s) in RCA: 145] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Anne Harrison-Marchand
- Laboratoire COBRA de l′Université de Rouen, INSA de Rouen, CNRS, UMR 6014 & FR 3038, IRCOF, Rue Tesnière, 76821 Mont St Aignan Cédex, France
| | - Florence Mongin
- Équipe Chimie et Photonique Moléculaires, Institut des Sciences Chimiques de Rennes, UMR 6226 CNRS-Université de Rennes 1, Bâtiment 10A, case 1003, Avenue du Général Leclerc, 35042 Rennes Cédex, France
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9
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Reich HJ. Role of Organolithium Aggregates and Mixed Aggregates in Organolithium Mechanisms. Chem Rev 2013; 113:7130-78. [DOI: 10.1021/cr400187u] [Citation(s) in RCA: 248] [Impact Index Per Article: 22.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Affiliation(s)
- Hans J. Reich
- Department of Chemistry, University of Wisconsin, Madison, Wisconsin 53706, United States
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10
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Tomasevich LL, Collum DB. Structure determination using the method of continuous variation: lithium phenolates solvated by protic and dipolar aprotic ligands. J Org Chem 2013; 78:7498-507. [PMID: 23806055 PMCID: PMC3759316 DOI: 10.1021/jo401080n] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The method of continuous variation (MCV) was used in conjunction with (6)Li NMR spectroscopy to characterize four lithium phenolates solvated by a range of solvents, including N,N,N',N'-tetramethylethylenediamine, Et2O, pyridine, protic amines, alcohols, and highly dipolar aprotic solvents. Dimers, trimers, and tetramers were observed, depending on the precise lithium phenolate-solvent combinations. Competition experiments (solvent swaps) provide insights into the relative propensities toward mixed solvation.
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Affiliation(s)
- Laura L. Tomasevich
- Department of Chemistry and Chemical Biology, Baker Laboratory, Cornell University, Ithaca, New York 14853-1301
| | - David B. Collum
- Department of Chemistry and Chemical Biology, Baker Laboratory, Cornell University, Ithaca, New York 14853-1301
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11
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Davis FA, Xu P. Asymmetric synthesis of anti-α-substituted β-amino ketones from sulfinimines. J Org Chem 2011; 76:3329-37. [PMID: 21417438 DOI: 10.1021/jo2002352] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Previously unknown, enantiopure, β-amino ketones were prepared in modest yield by addition of lithium reagents to N-sulfinyl anti-α-substituted β-amino Weinreb amides. Grignard reagents failed to add to these Weinreb amides in contrast to the syn-α-substituted isomers which did. The anti-α-substituted β-amino Weinreb amides were prepared by addition of LiN(OMe)Me to the corresponding N-sulfinyl anti-α-substituted β-amino esters because α-alkylation of N-sulfinyl β-amino Weinreb amide enolates resulted in poor diastereoselectivities.
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Affiliation(s)
- Franklin A Davis
- Department of Chemistry, Temple University, Philadelphia, Pennsylvania 19122, USA.
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12
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13
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Li D, Kagan G, Hopson R, Williard PG. Formula weight prediction by internal reference diffusion-ordered NMR spectroscopy (DOSY). J Am Chem Soc 2010; 131:5627-34. [PMID: 19323518 DOI: 10.1021/ja810154u] [Citation(s) in RCA: 124] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Formula weight (FW) information is important to characterize the composition, aggregation number, and solvation state of reactive intermediates and organometallic complexes. We describe an internal reference correlated DOSY method for calculating the FW of unknown species in different solvents with different concentrations. Examples for both the small molecule (DIPA) and the organometallic complex (aggregate 1) yield excellent correlations. We also found the relative diffusion rate is inversely proportional to the viscosity change of the solution, which is consistent with the theoretical Stokes-Einstein equation. The accuracy of the least-squares linear prediction r(2) and the percentage difference of FW prediction are directly related to the density change; greater accuracy was observed with decreasing density. We also discuss the guidelines and other factors for successful application of this internal reference correlated DOSY method. This practical method can be conveniently modified and applied to the characterization of other unknown molecules or complexes.
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Affiliation(s)
- Deyu Li
- Department of Chemistry, Brown University, Providence, Rhode Island 02912, USA
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14
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De Vries TS, Goswami A, Liou LR, Gruver JM, Jayne E, Collum DB. Lithium phenolates solvated by tetrahydrofuran and 1,2-dimethoxyethane: structure determination using the method of continuous variation. J Am Chem Soc 2009; 131:13142-54. [PMID: 19702308 PMCID: PMC2752606 DOI: 10.1021/ja9047784] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The method of continuous variation in conjunction with (6)Li NMR spectroscopy was used to characterize lithium phenolates solvated by tetrahydrofuran and 1,2-dimethoxyethane. The strategy relies on the formation of ensembles of homo- and heteroaggregated phenolates. The symmetries and concentration dependencies of the heteroaggregates attest to the aggregation numbers of the homoaggregates. The structurally diverse phenols afford substrate- and solvent-dependent combinations of lithium phenolate monomers, dimers, trimers, tetramers, and pentamers. We discuss the refinement of protocols for characterizing O-lithiated species. Computational studies examine further the substituent and solvent dependencies of aggregation.
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Affiliation(s)
- Timothy S De Vries
- Department of Chemistry and Chemical Biology, Baker Laboratory, Cornell University, Ithaca, New York 14853-1301, USA
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15
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Kolonko KJ, Biddle MM, Guzei IA, Reich HJ. Solution Structures of Lithium Enolates of Cyclopentanone, Cyclohexanone, Acetophenones, and Benzyl Ketones. Triple Ions and Higher Lithiate Complexes. J Am Chem Soc 2009; 131:11525-34. [DOI: 10.1021/ja903479p] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
| | - Margaret M. Biddle
- Department of Chemistry, University of Wisconsin, Madison, Wisconsin 53706
| | - Ilia A. Guzei
- Department of Chemistry, University of Wisconsin, Madison, Wisconsin 53706
| | - Hans J. Reich
- Department of Chemistry, University of Wisconsin, Madison, Wisconsin 53706
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16
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Däschlein C, Strohmann C. Structural Studies on (–)‐Sparteine‐Coordinated Lithiosilanes. Eur J Inorg Chem 2008. [DOI: 10.1002/ejic.200800792] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Christian Däschlein
- Technische Universität Dortmund, Anorganische Chemie, Otto‐Hahn‐Straße 6, 44227 Dortmund
| | - Carsten Strohmann
- Technische Universität Dortmund, Anorganische Chemie, Otto‐Hahn‐Straße 6, 44227 Dortmund
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17
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Gruver JM, Liou LR, McNeil AJ, Ramirez A, Collum DB. Solution structures of lithium enolates, phenolates, carboxylates, and alkoxides in the presence of N,N,N',N'-tetramethylethylenediamine: a prevalence of cyclic dimers. J Org Chem 2008; 73:7743-7. [PMID: 18781812 PMCID: PMC2636848 DOI: 10.1021/jo801532d] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The method of continuous variation was used to characterize lithium enolates, phenolates, carboxylates, and alkoxides solvated by N,N,N',N'-tetramethylethylenediamine (TMEDA). The method relies on characterizing an ensemble of homo- and heteroaggregates using (6)Li NMR spectroscopy. A combination of aggregate counts and symmetries, nearly statistical distributions, and quantitative parametric fits revealed that cyclic dimers are the dominant forms. Nonstatistical distributions favoring heteroaggregated dimers were observed when hindered enolates and carboxylates were mixed with unhindered enolates. Hindered (tertiary) alkoxides form higher aggregates (possibly hexamers), whereas hindered lithium phenolates appear to form TMEDA-solvated monomers.
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Affiliation(s)
- Jocelyn M. Gruver
- Contribution from the Department of Chemistry and Chemical Biology, Baker Laboratory, Cornell University, Ithaca, New York 14853-1301
| | - Lara R. Liou
- Contribution from the Department of Chemistry and Chemical Biology, Baker Laboratory, Cornell University, Ithaca, New York 14853-1301
| | - Anne J. McNeil
- Contribution from the Department of Chemistry and Chemical Biology, Baker Laboratory, Cornell University, Ithaca, New York 14853-1301
| | - Antonio Ramirez
- Contribution from the Department of Chemistry and Chemical Biology, Baker Laboratory, Cornell University, Ithaca, New York 14853-1301
| | - David B. Collum
- Contribution from the Department of Chemistry and Chemical Biology, Baker Laboratory, Cornell University, Ithaca, New York 14853-1301
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18
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Li D, Sun C, Williard PG. Characterization of a Chiral Enolate Aggregate and Observation of 6Li−1H Scalar Coupling. J Am Chem Soc 2008; 130:11726-36. [DOI: 10.1021/ja802114j] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Deyu Li
- Department of Chemistry, Brown University, Providence, Rhode Island 02912
| | - Chengzao Sun
- Department of Chemistry, Brown University, Providence, Rhode Island 02912
| | - Paul G. Williard
- Department of Chemistry, Brown University, Providence, Rhode Island 02912
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20
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Liou LR, McNeil AJ, Ramirez A, Toombes GES, Gruver JM, Collum DB. Lithium enolates of simple ketones: structure determination using the method of continuous variation. J Am Chem Soc 2008; 130:4859-68. [PMID: 18336025 PMCID: PMC2636850 DOI: 10.1021/ja7100642] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The method of continuous variation in conjunction with 6Li NMR spectroscopy was used to characterize lithium enolates derived from 1-indanone, cyclohexanone, and cyclopentanone in solution. The strategy relies on forming ensembles of homo- and heteroaggregated enolates. The enolates form exclusively chelated dimers in N,N,N',N'-tetramethylethylenediamine and cubic tetramers in tetrahydrofuran and 1,2-dimethoxyethane.
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Affiliation(s)
- Lara R Liou
- Department of Chemistry and Chemical Biology, Baker Laboratory, Cornell University, Ithaca, New York 14853-1301, USA
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21
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Li D, Hopson R, Li W, Liu J, Williard PG. 13C INEPT diffusion-ordered NMR spectroscopy (DOSY) with internal references. Org Lett 2008; 10:909-11. [PMID: 18251549 PMCID: PMC3220947 DOI: 10.1021/ol703039v] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
13C INEPT Diffusion-ordered NMR spectroscopy (DOSY) with an internal reference system was developed to study the aggregation state of THF-solvated LDA dimeric complex. Six components are clearly identified in the diffusion dimension, and their DOSY-generated 13C INEPT spectrum slices agree extremely well with their respective INEPT spectra. The correlation between log D and log FW of the linear least-squares fit to reference points of all components is exceptionally high: (r = 0.9985).
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Affiliation(s)
- Deyu Li
- Department of Chemistry, Brown University, Providence, RI 02912 USA
| | - Russell Hopson
- Department of Chemistry, Brown University, Providence, RI 02912 USA
| | - Weibin Li
- Department of Chemistry, Brown University, Providence, RI 02912 USA
| | - Jia Liu
- Department of Chemistry, Brown University, Providence, RI 02912 USA
| | - Paul G. Williard
- Department of Chemistry, Brown University, Providence, RI 02912 USA
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22
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Ramirez A, Sun X, Collum DB. Lithium Diisopropylamide-Mediated Enolization: Catalysis by Hemilabile Ligands. J Am Chem Soc 2006; 128:10326-36. [PMID: 16881665 DOI: 10.1021/ja062147h] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Structural, kinetic, and computational studies reveal the mechanistic complexities of a lithium diisopropylamide (LDA)-mediated ester enolization. Hemilabile amino ether MeOCH2CH2NMe2, binding as an eta1 (ether-bound) ligand in the reactant and as an eta2 (chelating) ligand in the transition structure, accelerates the enolization 10,000-fold compared with n-BuOMe. At the onset of the reaction, a dimer-based enolization prevails. As the reaction proceeds, significantly less reactive LDA-enolate mixed dimers appear and divert the reaction through monomer- and mixed dimer-based pathways. The mechanistic and computational investigations lead to a proof-of-principle ligand-catalyzed enolization in which an ancillary ligand allows the catalytic ligand to re-enter the catalytic cycle.
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Affiliation(s)
- Antonio Ramirez
- Department of Chemistry and Chemical Biology, Baker Laboratory, Cornell University, Ithaca, New York 14853-1301, USA
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