1821-12-1Relevant articles and documents
A Core–Shell-Structured Silver Nanowire/Nitrogen-Doped Carbon Catalyst for Enhanced and Multifunctional Electrofixation of CO2
Yang, Heng-Pan,Zhang, Han-Wen,Wu, Yu,Fan, Liang-Dong,Chai, Xiao-Yan,Zhang, Qian-Ling,Liu, Jian-Hong,He, Chuan-Xin
, p. 3905 - 3910 (2018)
Numerous catalysts have been successfully introduced for CO2 fixation in aqueous or organic systems. However, a single catalyst showing activity in both solvent types is still rare, to the best of our knowledge. We developed a core–shell-structured AgNW/NC700 composite using a Ag nanowire (NW) core encapsulated by a N-doped carbon (NC) shell at 700 °C. Through control experiments and density functional theory calculations, it was confirmed that Ag nanowires acted as the active sites for CO2 fixation and the uniformly coating of N-doped carbon created a CO2-rich environment around the Ag nanowires, which could significantly improve the catalytic activity of Ag nanowires for electrochemical CO2 fixation. Under mild conditions, up to 96 % faradaic efficiency of CO, 95 % yield of Ibuprofen and 92 % yield of propylene carbonate could be obtained in the electrochemical CO2 direct reduction, carboxylation and cycloaddition, respectively, using the same AgNWs/NC700 catalyst. These results might provide an alternative strategy for efficient electrochemical fixation of CO2.
Platinum/nitrogen-doped carbon/carbon cloth: A bifunctional catalyst for the electrochemical reduction and carboxylation of CO2 with excellent efficiency
Yang, Heng-Pan,Lin, Qing,Zhang, Han-Wen,Li, Guo-Dong,Fan, Liang-Dong,Chai, Xiao-Yan,Zhang, Qian-Ling,Liu, Jian-Hong,He, Chuan-Xin
, p. 4108 - 4111 (2018)
A novel Pt-NP@NCNF@CC composite was prepared by the electrospinning technique. It is a highly efficient and binder-free catalyst for the direct reduction and carboxylation of CO2 with halides. Formate with 91% Faradaic efficiency and 2-phenylpropionic acid with 99% yield could be obtained, respectively. Moreover, this catalyst has excellent stability and reusability.
The marked difference in conformational behavior of the two diastereomers of 7-substituted-1,1-dichloro-7b-((Z)-8-chloro-6,7-dihydro-5H-benzo[7]annulen-9- yl)-1a,2,3,7b-tetrahydro-1H-cyclopropa[a]naphthalene, single crystal X-ray, 1H NMR and AM1 studies
Roshan, Hamid,Rashidi-Ranjbar, Parviz
, p. 59 - 65 (2010)
The 7-substituted of 1 and 2 were synthesized and conformational analysis carried out. While 7-substituted of 2 show two conformers in solution, 7-substituted of 1 show only one form in solution. AM1 semi-empirical molecular orbital calculations show that the conformation of cycloheptadiene ring in 1 and 2 is a twist boat form. In this conformation, the C-7 substituents can be oriented in pseudo equatorial (exo) and pseudo axial (endo) positions. The 3J calculation with Haasnoot equation on optimized structure of 2 reproduces the observed 3J coupling constants in exo and endo forms. Ring inversion of cycloheptadiene moiety in substituted 2 interconvert the e′-a′ (exo-endo) positions. The 3J calculation on optimized structure of 1 shows that 7-substitution is in pseudo equatorial (exo) direction, as found in the crystal structure of 1a by single crystal X-ray crystallography. The barrier to ring inversion in 2a is determined by dynamic 1H NMR spectroscopy to be ΔG≠(335K) = 68.0 ± 0.5 kJ/mol.
Mechanochemical Grignard Reactions with Gaseous CO2 and Sodium Methyl Carbonate**
Pfennig, Victoria S.,Villella, Romina C.,Nikodemus, Julia,Bolm, Carsten
supporting information, (2022/01/22)
A one-pot, three-step protocol for the preparation of Grignard reagents from organobromides in a ball mill and their subsequent reactions with gaseous carbon dioxide (CO2) or sodium methyl carbonate providing aryl and alkyl carboxylic acids in up to 82 % yield is reported. Noteworthy are the short reaction times and the significantly reduced solvent amounts [2.0 equiv. for liquid assisted grinding (LAG) conditions]. Unexpectedly, aryl bromides with methoxy substituents lead to symmetric ketones as major products.
Pd-Catalyzed Regioselective Branched Hydrocarboxylation of Terminal Olefins with Formic Acid
Chu, Jianxiao,Guo, Jianqiong,Ren, Wenlong,Shi, Yian,Shi, Yuan,Wang, Mingzhou,Zhou, Jintao
supporting information, p. 886 - 891 (2022/02/07)
A regioselective Pd-catalyzed hydrocarboxylation of terminal olefins with HCOOH is described. A wide variety of branched carboxylic acids can readily be obtained with high regioselectivities under mild reaction conditions. The reaction is operationally simple and requires no handling of toxic CO. The ligand and LiCl are important factors for reaction reactivity and selectivity.
Palladium-Catalyzed Direct C-H Arylation of 3-Butenoic Acid Derivatives
Yang, Shan,Liu, Lingling,Zhou, Zheng,Huang, Zhibin,Zhao, Yingsheng
supporting information, p. 296 - 299 (2021/01/13)
We report herein a direct method to synthesize 4-aryl-3-butenoic acid through a carboxylic-acid-directed oxidative Heck reaction. The various 4-aryl-3-butenoic acids are easily prepared in moderate to good yields. In view of the promising bioactivity of 4-phenyl-3-butenoic acid previously reported, its derivatives reported here may be bioactive.
Suppressing carboxylate nucleophilicity with inorganic salts enables selective electrocarboxylation without sacrificial anodes
Corbin, Nathan,Lazouski, Nikifar,Manthiram, Karthish,Steinberg, Katherine,Yang, Deng-Tao
, p. 12365 - 12376 (2021/10/08)
Although electrocarboxylation reactions use CO2as a renewable synthon and can incorporate renewable electricity as a driving force, the overall sustainability and practicality of this process is limited by the use of sacrificial anodes such as magnesium and aluminum. Replacing these anodes for the carboxylation of organic halides is not trivial because the cations produced from their oxidation inhibit a variety of undesired nucleophilic reactions that form esters, carbonates, and alcohols. Herein, a strategy to maintain selectivity without a sacrificial anode is developed by adding a salt with an inorganic cation that blocks nucleophilic reactions. Using anhydrous MgBr2as a low-cost, soluble source of Mg2+cations, carboxylation of a variety of aliphatic, benzylic, and aromatic halides was achieved with moderate to good (34-78%) yields without a sacrificial anode. Moreover, the yields from the sacrificial-anode-free process were often comparable or better than those from a traditional sacrificial-anode process. Examining a wide variety of substrates shows a correlation between known nucleophilic susceptibilities of carbon-halide bonds and selectivity loss in the absence of a Mg2+source. The carboxylate anion product was also discovered to mitigate cathodic passivation by insoluble carbonates produced as byproducts from concomitant CO2reduction to CO, although this protection can eventually become insufficient when sacrificial anodes are used. These results are a key step toward sustainable and practical carboxylation by providing an electrolyte design guideline to obviate the need for sacrificial anodes.
Ligand-Controlled Regiodivergence in Nickel-Catalyzed Hydroarylation and Hydroalkenylation of Alkenyl Carboxylic Acids**
Deng, Ruohan,Engle, Keary M.,Fu, Yue,Gao, Yang,Li, Zi-Qi,Liu, Peng,Tran, Van T.
supporting information, p. 23306 - 23312 (2020/10/19)
A nickel-catalyzed regiodivergent hydroarylation and hydroalkenylation of unactivated alkenyl carboxylic acids is reported, whereby the ligand environment around the metal center dictates the regiochemical outcome. Markovnikov hydrofunctionalization products are obtained under mild ligand-free conditions, with up to 99 % yield and >20:1 selectivity. Alternatively, anti-Markovnikov products can be accessed with a novel 4,4-disubstituted Pyrox ligand in excellent yield and >20:1 selectivity. Both electronic and steric effects on the ligand contribute to the high yield and selectivity. Mechanistic studies suggest a change in the turnover-limiting and selectivity-determining step induced by the optimal ligand. DFT calculations reveal that in the anti-Markovnikov pathway, repulsion between the ligand and the alkyl group is minimized (by virtue of it being 1° versus 2°) in the rate- and regioselectivity-determining transmetalation transition state.
Organocatalyzed Birch Reduction Driven by Visible Light
Cole, Justin P.,Chen, Dian-Feng,Kudisch, Max,Pearson, Ryan M.,Lim, Chern-Hooi,Miyake, Garret M.
supporting information, p. 13573 - 13581 (2020/09/03)
The Birch reduction is a powerful synthetic methodology that uses solvated electrons to convert inert arenes to 1,4-cyclohexadienes - valuable intermediates for building molecular complexity. Birch reductions traditionally employ alkali metals dissolved in ammonia to produce a solvated electron for the reduction of unactivated arenes such as benzene (Ered -3.42 V vs SCE). Photoredox catalysts have been gaining popularity in highly reducing applications, but none have been reported to demonstrate reduction potentials powerful enough to reduce benzene. Here, we introduce benzo[ghi]perylene imides as new organic photoredox catalysts for Birch reductions performed at ambient temperature and driven by visible light from commercially available LEDs. Using low catalyst loadings (1 mol percent), benzene and other functionalized arenes were selectively transformed to 1,4-cyclohexadienes in moderate to good yields in a completely metal-free reaction. Mechanistic studies support that this unprecedented visible-light-induced reactivity is enabled by the ability of the organic photoredox catalyst to harness the energy from two visible-light photons to affect a single, high-energy chemical transformation.
A recyclable, metal-free mechanochemical approach for the oxidation of alcohols to carboxylic acids
Carr, Preston,Denlinger, Kendra Leahy,Mack, James,Waddell, Daniel C.
, (2020/01/28)
The oxidation of primary alcohols under mechanochemical conditions in a Spex8000M Mixer/Mill was investigated. To facilitate ease of separation and recyclability, a polystyrene-bound version of a TEMPO catalyst was employed. When paired with Oxone in a stainless-steel vial with a stainless-steel ball, several primary alcohols were successfully oxidized to the corresponding carboxylic acids. The product was isolated using gravity filtration, which also allowed for the polystyrene-bound TEMPO catalyst to be recovered and reused in subsequent oxidation reactions. Furthermore, it was demonstrated that the size and steric hindrance of the primary alcohol does not hinder the rate of the reaction. Finally, the aldehyde was selectively obtained from a primary alcohol under ball milling conditions by using a combination of non-supported TEMPO with a copper vial and copper ball.
