Room Temperature Alkali Metal Reduction of Carbon Dioxide

The reduction of the relatively inert carbon–oxygen bonds of CO2 to access useful CO2-derived organic products is one of the most important fundamental challenges in synthetic chemistry. Facilitating this bond-cleavage using earth-abundant, non-toxic main group elements (MGEs) is especially arduous because of the difficulty in achieving strong inner-sphere interactions between CO2 and the MGE. Herein we report the first successful chemical reduction of CO2 at room temperature by alkali metals, promoted by a cyclic(alkyl)(amino) carbene (CAAC). One-electron reduction of CAAC-CO2 adduct (1) with lithium, sodium or potassium metal yields stable monoanionic radicals clusters [M(CAAC–CO2)]n(M = Li, Na, K, 2-4) and two-electron alkali metal reduction affords open-shell, dianionic clusters of the general formula [M2(CAAC–CO2)]n (5-8). It is notable that these crystalline clusters of reduced CO2 may also be isolated via the “one-pot” reaction of free CO2 with free CAAC followed by the addition of alkali metals – a reductive process which does not occur in the absence of carbene. Each of the products 2-8 were investigated using a combination of experimental and theoretical methods.

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Cyclic(Alkyl)(Amino) Carbene-Assisted Reduction of Carbon Dioxide: Isolation of Crystalline Alkali Metal Clusters of Supported CO2 Radical Anions and Dianions

10.26434/chemrxiv.12665336.v1 ◽

2020 ◽

Author(s):

Lucas A. Freeman ◽

Akachukwu D. Obi ◽

Haleigh R. Machost ◽

Andrew Molino ◽

Asa W. Nichols ◽

...

Keyword(s):

Alkali Metals ◽

Room Temperature ◽

Bond Activation ◽

Theoretical Calculations ◽

Chemical Reduction ◽

Structural Characteristics ◽

Open Shell ◽

X Ray Crystallography ◽

Earth Abundant ◽

Alkali Metal Clusters

The reduction of the relatively inert carbon–oxygen bonds of CO2to access useful CO2-derived organic products is one of the most important fundamental challenges in synthetic chemistry. Achieving this reduction using earth-abundant main group elements (MGEs) is especially arduous because of the difficulty in achieving strong inner-sphere reactions and bond activation events between CO2and the MGE. Herein we report the first successful chemical reduction of a zwitterionic carbene-CO2adduct by either one or two equivalents of light alkali metals to form isolable, room-temperature-stable crystalline clusters exhibiting remarkably diverse electronic and structural characteristics. The reduction of a CAAC-CO2adduct [CAAC–CO2, 1, CAAC = cyclic (alkyl)(amino) carbene] with one equivalent of lithium, sodium or potassium metal yields the monoanionic radicals (THF)3Li2(CAAC–CO2)2(2), (THF)4Na4(CAAC–CO2)4(3), or (THF)4K4(CAAC–CO2)4(4). The reduction of 1by two or more equivalents of lithium, sodium, or potassium yields the open-shell, dianionic clusters (THF)2Li6(CAAC–CO2)3(5), Li12(CAAC–CO2)6(6), Na12(CAAC–CO2)6(7), and K10(CAAC–CO2)5(8). Each of the clusters was studied by a combination of X-ray crystallography, FTIR, UV-Vis, EPR and NMR spectroscopies, and theoretical calculations. <a>The synthetic transformation described in this report results in the facile net reduction of CO2at room temperature by lithium, sodium, and potassium metal without the need for additional metallic promoters, catalysts, or reagents – a process which does not occur in the absence of carbene.</a>

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One-pot Preparation of Antioxidized Copper Fine Particles with a Unique Structure by Chemical Reduction at Room Temperature

Chemistry Letters ◽

10.1246/cl.2010.548 ◽

2010 ◽

Vol 39 (6) ◽

pp. 548-549 ◽

Cited By ~ 31

Author(s):

Tetsu Yonezawa ◽

Naoki Nishida ◽

Atsushi Hyono

Keyword(s):

Room Temperature ◽

Fine Particles ◽

Chemical Reduction ◽

One Pot ◽

Unique Structure

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Visible-light photoredox-catalyzed C–O bond cleavage of diaryl ethers by acridinium photocatalysts at room temperature

Nature Communications ◽

10.1038/s41467-020-19944-x ◽

2020 ◽

Vol 11 (1) ◽

Author(s):

Fang-Fang Tan ◽

Xiao-Ya He ◽

Wan-Fa Tian ◽

Yang Li

Keyword(s):

Carboxylic Acid ◽

Visible Light ◽

Room Temperature ◽

Acid Catalysis ◽

Bond Cleavage ◽

Diphenyl Ether ◽

One Pot ◽

Diaryl Ethers ◽

Diaryl Ether ◽

High Bond

AbstractCleavage of C–O bonds in lignin can afford the renewable aryl sources for fine chemicals. However, the high bond energies of these C–O bonds, especially the 4-O-5-type diaryl ether C–O bonds (~314 kJ/mol) make the cleavage very challenging. Here, we report visible-light photoredox-catalyzed C–O bond cleavage of diaryl ethers by an acidolysis with an aryl carboxylic acid and a following one-pot hydrolysis. Two molecules of phenols are obtained from one molecule of diaryl ether at room temperature. The aryl carboxylic acid used for the acidolysis can be recovered. The key to success of the acidolysis is merging visible-light photoredox catalysis using an acridinium photocatalyst and Lewis acid catalysis using Cu(TMHD)2. Preliminary mechanistic studies indicate that the catalytic cycle occurs via a rare selective electrophilic attack of the generated aryl carboxylic radical on the electron-rich aryl ring of the diphenyl ether. This transformation is applied to a gram-scale reaction and the model of 4-O-5 lignin linkages.

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Die Reduktion von Triphenylphosphan-Derivaten zu ihren Radikalanionen und zum Dibenzophosphol-Radikaldianion [1] / The Reduction of Triphenylphosphane Derivatives to their Radical Anions and to the Radical Dianion of Dibenzophosphole [1]

Zeitschrift für Naturforschung B ◽

10.1515/znb-1982-1104 ◽

1982 ◽

Vol 37 (11) ◽

pp. 1382-1387 ◽

Cited By ~ 15

Author(s):

Wolfgang Kaim ◽

Peter Hänel ◽

Hans Bock

Keyword(s):

Low Temperature ◽

Alkali Metal ◽

Ring Closure ◽

Metal Reduction ◽

Paramagnetic Species ◽

Radical Anions ◽

Spin Distribution ◽

Pyramidal Geometry ◽

Mercury Cathode ◽

Electron Reduction

Triphenylphosphane 1, its oxide 2 and sulfide 3 undergo one-electron reduction at a mercury cathode in DMF to yield the corresponding radical anions. ESE analysis of the paramagnetic species is facilitated by deuteration and suggests a pyramidal geometry of the radicals. Reduction with potassium metal in DME at low temperature yields also radical anions for 2 and 3. The phosphane 1, however, reacts under phenyl cleavage and potassiumphenyl-assisted ring closure to the dianion of 5H-dibenzophosphole 4. This radical 4· ⊖⊖ is also obtainod by alkali metal reduction of P-phenyldibenzophosphole o, and its spin distribution is compared to iso-.-π-electronic radicals containing CH, N, O, S, or Se links instead of the phosphorus atom.

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Visible-Light Photoredox-Catalyzed C–O Bond Cleavage of Diaryl Ethers by Acridinium Photocatalysts at Room Temperature

10.21203/rs.3.rs-52259/v1 ◽

2020 ◽

Author(s):

Fang-Fang Tan ◽

Xiao-Ya He He ◽

Wan-Fa Tian ◽

Yang Li

Keyword(s):

Visible Light ◽

Room Temperature ◽

Acid Catalysis ◽

Bond Cleavage ◽

Diphenyl Ether ◽

Mechanistic Studies ◽

Electrophilic Attack ◽

One Pot ◽

Diaryl Ethers ◽

Diaryl Ether

Abstract We have developed visible-light photoredox-catalyzed C–O bond cleavage of diaryl ethers by an acidolysis with an aryl car-boxylic acid and a following one-pot hydrolysis. Two phenols are obtained from a diaryl ether at room temperature. The aryl carboxylic acid used for the acidolysis can be recovered. The key to success of the acidolysis is merging visible-light photore-dox catalysis with a new acridinium photocatalyst and Lewic acid catalysis with Cu(TMHD)2. Preliminary mechanistic studies indicate that the catalytic cycle occurs via a rare selective electrophilic attack of the generated aryl carboxylic radical on the electron-rich aryl ring of diphenyl ether. This transformation is applied to a gram-scale reaction and the model of 4-O-5 lignin linkages.

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A Series of Metal-Organic Frameworks for Selective CO2 Capture and Catalytic Oxidative Carboxylation of Olefins

10.26434/chemrxiv.7068509 ◽

2018 ◽

Author(s):

Huong T. D. Nguyen ◽

Y B. N. Tran ◽

Hung N. Nguyen ◽

Tranh C. Nguyen ◽

Felipe Gándara ◽

...

Keyword(s):

Room Temperature ◽

Gas Adsorption ◽

New Materials ◽

One Pot ◽

Acid Gas ◽

Naphthalene Diimide ◽

Styrene Carbonate ◽

Metal Organic ◽

Adsorption Of Co ◽

The One

Three novel lanthanide metal˗organic frameworks (Ln-MOFs), namely MOF-590, -591, and -592 were constructed from a naphthalene diimide tetracarboxylic acid. Gas adsorption measurements of MOF-591 and -592 revealed good adsorption of CO2 (low pressure, at room temperature) and moderate CO2 selectivity over N2 and CH4. Accordingly, breakthrough measurements were performed on a representative MOF-592, in which the separation of CO2 from binary mixture containing N2 and CO2 was demonstrated without any loss in performance over three consecutive cycles. Moreover, MOF-590, MOF-591, and MOF-592 exhibited catalytic activity in the one-pot synthesis of styrene carbonate from styrene and CO2 under mild conditions (1 atm CO2, 80 °C, and solvent-free). Among the new materials, MOF-590 revealed a remarkable efficiency with exceptional conversion (96%), selectivity (95%), and yield (91%).

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A Study on the Rearrangement of Dialkyl 1-Aryl-1-hydroxymethylphosphonates to Benzyl Phosphates

Current Organic Chemistry ◽

10.2174/1385272824666200226114306 ◽

2020 ◽

Vol 24 (4) ◽

pp. 465-471 ◽

Cited By ~ 2

Author(s):

Zita Rádai ◽

Réka Szabó ◽

Áron Szigetvári ◽

Nóra Zsuzsa Kiss ◽

Zoltán Mucsi ◽

...

Keyword(s):

Quantum Chemical ◽

Room Temperature ◽

Phase Transfer ◽

One Pot ◽

Substrate Dependence ◽

Triethylbenzylammonium Chloride ◽

One Step ◽

The Pudovik Reaction ◽

The One ◽

Solid Liquid

The phospha-Brook rearrangement of dialkyl 1-aryl-1-hydroxymethylphosphonates (HPs) to the corresponding benzyl phosphates (BPs) has been elaborated under solid-liquid phase transfer catalytic conditions. The best procedure involved the use of triethylbenzylammonium chloride as the catalyst and Cs2CO3 as the base in acetonitrile as the solvent at room temperature. The substrate dependence of the rearrangement has been studied, and the mechanism of the transformation under discussion was explored by quantum chemical calculations. The key intermediate is an oxaphosphirane. The one-pot version starting with the Pudovik reaction has also been developed. The conditions of this tandem transformation were the same, as those for the one-step HP→BP conversion.

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One-pot Synthesis of Pyrazolone Sulfones by Iodine-catalyzed Sulfenylation of Pyrazolones with Aryl Sulfonyl Hydrazides Followed by Oxidation in Water

Current Organic Synthesis ◽

10.2174/1570179414666171020113745 ◽

2018 ◽

Vol 15 (3) ◽

pp. 380-387

Author(s):

Xia Zhao ◽

Xiaoyu Lu ◽

Lipeng Zhang ◽

Tianjiao Li ◽

Kui Lu

Keyword(s):

Double Bond ◽

Efficient Method ◽

Room Temperature ◽

Sulfonyl Chloride ◽

Antibacterial Activities ◽

Oxidation Reactions ◽

Reaction Conditions ◽

One Pot ◽

X Ray ◽

Amide Form

Aim and Objective: Pyrazolone sulfones have been reported to exhibit herbicidal and antibacterial activities. In spite of their good bioactivities, only a few methods have been developed to prepare pyrazolone sulfones. However, the substrate scope of these methods is limited. Moreover, the direct sulfonylation of pyrazolone by aryl sulfonyl chloride failed to give pyrazolone sulfones. Thus, developing a more efficient method to synthesize pyrazolone sulfones is very important. Materials and Method: Pyrazolone, aryl sulphonyl hydrazide, iodine, p-toluenesulphonic acid and water were mixed in a sealed tube, which was heated to 100°C for 12 hours. The mixture was cooled to 0°C and m-CPBA was added in batches. The mixture was allowed to stir for 30 min at room temperature. The crude product was purified by silica gel column chromatography to afford sulfuryl pyrazolone. Results: In all cases, the sulfenylation products were formed smoothly under the optimized reaction conditions, and were then oxidized to the corresponding sulfones in good yields by 3-chloroperoxybenzoic acid (m-CPBA) in water. Single crystal X-ray analysis of pyrazolone sulfone 4aa showed that the major tautomer of pyrazolone sulfones was the amide form instead of the enol form observed for pyrazolone thioethers. Moreover, the C=N double bond isomerized to form an α,β-unsaturated C=C double bond. Conclusion: An efficient method to synthesize pyrazolone thioethers by iodine-catalyzed sulfenylation of pyrazolones with aryl sulfonyl hydrazides in water was developed. Moreover, this method was employed to synthesize pyrazolone sulfones in one-pot by subsequent sulfenylation and oxidation reactions.

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