Imidazol(in)ium carboxylates as N-heterocyclic carbene ligand precursors for Suzuki–Miyaura reactions

Tudose, Adriana; Delaude, Lionel; Bleich, André; Demonceau, Albert

doi:10.1016/j.tetlet.2006.09.139

Cited by 49 publications

(41 citation statements)

References 57 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…It is known that carbenes can form upon the dissolution of metal oxides in imidazolium ionic liquids 42 and that imidazolium dithiocarboxylates can act as precursors for N-heterocyclic carbenes. 43 Hence, an experiment was undertaken to test for the presence of Nheterocyclic carbenes as an intermediate in an IL aq -based leaching mechanism: kinetically slow in ambient, uncatalysed conditions [3+2] cycloaddition of benzylazide and phenylacetylene is catalysed by Cu(I)-carbene species, which may be formed via deprotonation at the imidazolium C2 position. However, no evidence was found to suggest that any cyclised product had formed in the presence of IL leachates (see Figure S10-S12 for the reaction scheme and spectra).…”

Section: Article This Journal Is © the Royal Society Of Chemistry 20xxmentioning

confidence: 99%

Ionic liquids for metal extraction from chalcopyrite: solid, liquid and gas phase studies

Kuzmina

Symianakis

Godfrey

et al. 2017

Phys. Chem. Chem. Phys.

View full text Add to dashboard Cite

We are pleased to submit for publication in Physical Chemistry Chemical Physics the attached manuscript entitled " Ionic liquids for metal extraction from chalcopyrite: solid, liquid and gas phase studies".In this work, we report an application of aqueous solutions of ionic liquids (ILs) based on imidazolium and ethylammonium cations, and hydrogensulfate, nitrate, acetate and dicyanamide anions in a complex study of leaching of Cu and Fe metals from naturally occurring chalcopyrite ore. This is the first study, to our knowledge, providing a systematic comparison of the leaching performance of ILs composed of different cations and anions, and without added oxidants such as ferric ions and dissolved oxygen.We characterised the liquid, solid and gas phases of the leaching systems and showed that the anion plays an important role in defining the leaching ability of ILs. Our results indicated that in neat IL aqueous solutions, without the addition of oxidants, the surface chemical reaction is the rate determining step. EDS/XPS spectroscopy was performed in combination with SEM imaging to study the evolution of the chalcopyrite surface upon leaching. Gas Chromatography coupled with Mass Spectroscopy was applied to investigate the evolution of species in the gas phase upon leaching, and novel dependencies between the evolution of gas species, formation of oxide layer and metal extraction efficiency were noticed and are summarised.Taken together, we feel that the work will have significant impact on the development of efficient solvent systems for metal extraction from copper and iron bearing ores. The obtained information on the solubility of Cu and Fe in ILs with different structures will be useful for the design of highly efficient IL solvents for chalcopyrite dissolution. The initial data obtained for solid and gas phase alterations upon leaching are essential for further investigation of the complete mechanism of chalcopyrite leaching in IL solutions. The discovered dependence between extinction coefficient of copper, ε(Cu), Page 1 of 23Physical Chemistry Chemical Physics and performance of the studied leaching systems is suggested to be used to predict extraction properties of lixiviant.Therefore this work carries not only fundamental information of the solubility of chalcopyrite in ILs, but also presents a further path to study the mechanism of this complex process. We commend this manuscript to you for publication in Physical Chemistry Chemical Physics and look forward to your response.Sincerely, Prof. Tom Welton Page 2 of 23 Physical Chemistry Chemical PhysicsIonic liquids for metal extraction from chalcopyrite: solid, liquid and gas phase studies O. Kuzmina, E. Symianakis, D. Godfrey, T. Albrecht and T. WeltonNon-oxidative leaching in ionic liquids revealed novel dependencies between the evolution of gas species, passivation layers and metal extraction efficiency. We studied leaching of Cu and Fe from naturally occurring chalcopyrite ore using aqueous solutions of ionic liquids based on imidazolium and ethylam...

show abstract

Section: Article This Journal Is © the Royal Society Of Chemistry 20xxmentioning

confidence: 99%

Ionic liquids for metal extraction from chalcopyrite: solid, liquid and gas phase studies

Kuzmina

Symianakis

Godfrey

et al. 2017

Phys. Chem. Chem. Phys.

View full text Add to dashboard Cite

show abstract

“…Attempts to convert this salt into the ester by deprotonation with nBuLi, followed by the addition of (MeO) 2 CO failed, presumably due to the low acidity of 4-H of the pyrazolium salt. It is also known from the literature, that the in situ deprotonation of 1,2,3,5-tetrasubstituted pyrazolium salts with basic metal precursors such as Pd(OAc) 2 or Ag 2 O was unsuccessful [28,35]. In agreement with these observations, the remote N-heterocyclic carbene 14 could not be de According to a DFT calculation, the deprotonation of the pyrazolium salt 1 to the N-heterocyclic carbene 2 by methoxide under formation of methanol is by 86.8 kJ mol −1 more favorable than the analogous deprotonation of 14 to the remote N-heterocyclic carbene 15.…”

Section: Resultsmentioning

confidence: 99%

Synthesis of a Pyrazol-3-ylidene Palladium Complex, Pyrazolium Salts and Mesomeric Betaines of Pyrazole as N-Heterocyclic Carbene Precursors

Dreger

Nieger

Drafz

et al. 2012

Zeitschrift Für Naturforschung B

View full text Add to dashboard Cite

show abstract

“…In Section 4.2, we have mentioned the carboxylation of 1,3-dialkyimidazolium chlorides with CO2/Na2CO3 and the use of 1,3-dialkyimidazolium-2-carboxylates as CO2-carriers in the carboxylation of C(sp 3 )-H acidic compounds. NHC-CO2 compounds can be also synthesized by carboxylation of imidazol-2-yilidene precursors as reported by Kuhn in 1999 (Scheme 55b) [134] or by carboxylation of imidazol-2-ylidenes generated in situ by deprotonation of imidazolium salts (139) with potassium tert-butoxide or KN(SiMe3)2 as reported by Louie [135] and Delaude [136] Scheme 54. (a) Reaction mechanism proposed by Skrydstrup for carboxylation/cyclization of 2-alkynyl indoles with CO 2 ; (b) Bifunctional activation mechanism proposed on the basis of DFT analysis by Wong and coworkers.…”

Section: Base-promoted Carboxylation Of Aromatic and Heteroaromatic Cmentioning

confidence: 99%

Direct Carboxylation of C(sp3)-H and C(sp2)-H Bonds with CO2 by Transition-Metal-Catalyzed and Base-Mediated Reactions

Tommasi

2017

Catalysts

View full text Add to dashboard Cite

This review focuses on recent advances in the field of direct carboxylation reactions of C(sp 3 )-H and C(sp 2 )-H bonds using CO 2 encompassing both transition-metal-catalysis and base-mediated approach. The review is not intended to be comprehensive, but aims to analyze representative examples from the literature, including transition-metal catalyzed carboxylation of benzylic and allylic C(sp 3 )-H functionalities using CO 2 which is at a "nascent stage". Examples of light-driven carboxylation reactions of unactivated C(sp 3 )-H bonds are also considered. Concerning C(sp 3 )-H and C(sp 2 )-H deprotonation reactions mediated by bases with subsequent carboxylation of the carbon nucleophile, few examples of catalytic processes are reported in the literature. In spite of this, several examples of base-promoted reactions integrating "base recycling" or "base regeneration (through electrosynthesis)" steps have been reported. Representative examples of synthetically efficient, base-promoted processes are included in the review.

show abstract

Imidazol(in)ium carboxylates as N-heterocyclic carbene ligand precursors for Suzuki–Miyaura reactions

Cited by 49 publications

References 57 publications

Ionic liquids for metal extraction from chalcopyrite: solid, liquid and gas phase studies

Ionic liquids for metal extraction from chalcopyrite: solid, liquid and gas phase studies

Synthesis of a Pyrazol-3-ylidene Palladium Complex, Pyrazolium Salts and Mesomeric Betaines of Pyrazole as N-Heterocyclic Carbene Precursors

Direct Carboxylation of C(sp3)-H and C(sp2)-H Bonds with CO2 by Transition-Metal-Catalyzed and Base-Mediated Reactions

Contact Info

Product

Resources

About