92-94-4Relevant articles and documents
Mechanistic and kinetic studies of cobalt macrocycles in a photochemical CO2 reduction system: Evidence of Co-CO2 adducts as intermediates
Ogata, Tomoyuki,Yanagida, Shozo,Brunschwig, Bruce S.,Fujita, Etsuko
, p. 6708 - 6716 (1995)
Cobalt macrocycles mediate electron transfer in the photoreduction of CO2 with p-terphenyl as a photosensitizer and a tertiary amine as a sacrificial electron donor in a 5:1 acetonitrile/methanol mixture. The mechanism and kinetics of this system have been studied by continuous and flash photolysis techniques. Transient spectra provide evidence for the sequential formation of the p-terphenyl radical anion, the CoIL+ complex, the [CoIL-CO2]+ complex, and the [S-CoIIIL-(CO22-)]+ complex (L = HMD = 5,7,7,12,14,14-hexamethyl-1,4,8,11-tetraazacyclotetradeca-4,11-diene; S = solvent) in the catalytic system. The electron-transfer rate constant for the reaction of p-terphenyl radical anion with CoIIL2+ is 1.1 × 1010 M-1 s-1 and probably diffusion controlled because of the large driving force (～+1.1 V). Flash photolysis studies yield a rate constant 1.7 × 108 M-1 s-1 and an equilibrium constant 1.1 × 104 M-1 for the binding of CO2 to CoIL+ in the catalytic system. These are consistent with those previously obtained by conventional methods in acetonitrile. Studies of catalytic systems with varying cobalt macrocycles highlight some of the factors controlling the kinetics of the photoreduction of CO2. Steric hindrance and reduction potentials are important factors in the catalytic activity for photochemical CO2 reduction.
The synthesis of SBA-Pr-3AP@Pd and its application as a highly dynamic, eco-friendly heterogeneous catalyst for Suzuki–Miyaura cross-coupling reaction
Mohajer, Fatemeh,Mohammadi Ziarani, Ghodsi,Badiei, Alireza
, p. 4909 - 4922 (2020)
The hexagonal mesoporous organic–inorganic hybrid as a new nanocatalyst was prepared by the treatment of SBA-15 with (3-chloropropyl)triethoxysilane, the 2,4,6-triamino pyrimidine ligand, and then PdCl2 to obtain the SBA-15-propyl-triamino pyrimidine@Pd called as SBA-Pr-3AP@Pd, which was examined through Suzuki–Miyaura cross-coupling reaction by several aryl halides and phenylboronic acid under mild conditions in high yield.
Postsynthetic Metalation of a Robust Hydrogen-Bonded Organic Framework for Heterogeneous Catalysis
Han, Bin,Wang, Hailong,Wang, Chiming,Wu, Hui,Zhou, Wei,Chen, Banglin,Jiang, Jianzhuang
, p. 8737 - 8740 (2019)
Hydrogen-bonded organic framework (HOF)-based catalysts still remain unreported thus far due to their relatively weak stability. In the present work, a robust porous HOF (HOF-19) with a Brunauer-Emmett-Teller surface area of 685 m2 g-1 was reticulated from a cagelike building block, amino-substituted bis(tetraoxacalix[2]arene[2]triazine), depending on the hydrogen bonding with the help of π-πinteractions. The postsynthetic metalation of HOF-19 with palladium acetate afforded a palladium(II)-containing heterogeneous catalyst with porous hydrogen-bonded structure retained, which exhibits excellent catalytic performance for the Suzuki-Miyaura coupling reaction with the high isolation yields (96-98%), prominent stability, and good selectivity. More importantly, by simple recrystallization, the catalytic activity of deactivated species can be recovered from the isolation yield 46% to 92% for 4-bromobenzonitrile conversion at the same conditions, revealing the great application potentials of HOF-based catalysts.
Murray,Kaplan
, p. 2903,2904, 2906 (1965)
Synthesis and characterization of palladium nanoparticles immobilized on graphene oxide functionalized with triethylenetetramine or 2,6-diaminopyridine and application for the Suzuki cross-coupling reaction
Boukherroub, Rabah,Mirza-Aghayan, Maryam,Mohammadi, Marzieh
, (2021/11/22)
Graphene oxide (GO) was functionalized with two organic ligands, triethylenetetramine (TETA) or 2,6-diaminopyridine (DAP), followed by palladium nanoparticles (Pd NPs) for the synthesis of Pd NPs/GO-TETA and Pd NPs/GO-DAP nanocomposites, respectively. The two heterogeneous nanocomposites were fully characterized and their efficiency was investigated for C[sbnd]C bond formation for the synthesis of biaryl compounds via the Suzuki cross-coupling reaction of aryl halides with arylboronic acid derivatives. The obtained results indicated that the Pd NPs/GO-TETA nanocomposite was more effective in the Suzuki coupling reaction as compared to Pd NPs/GO-DAP. Thus, the Suzuki cross-coupling reaction of different aryl halides with arylboronic acid derivatives using Pd NPs/GO-TETA nanocomposite catalyst in the presence of Na2CO3 as base in DMF/H2O (1/1) as solvent at 90 °C was carried out to afford the desired biaryl compounds in high to excellent yields (81–100%) and short reaction times (10–90 min). Additionally, Pd NPs/GO-TETA nanocomposite can be recovered and reused for 8 consecutive runs without any apparent loss of its catalytic activity, proving its high stability and potential use in organic transformations.
Silk?Fibroin-Supported Palladium Catalyst for Suzuki-Miyaura and Ullmann Coupling Reactions of Aryl Chlorides
Albano, Gianluigi,Farinola, Gianluca M.,Giannini, Cinzia,Musio, Roberta,Omenetto, Fiorenzo G.,Rizzo, Giorgio,Sibillano, Teresa
, (2022/02/03)
Recently, we have reported the preparation of a silk fibroin-supported Palladium catalyst (Pd/SF) and its use in the Suzuki-Miyaura cross-coupling of aryl iodides. Since its synthetic applicability and structural features are still far from being fully ex
Solvent coordination to palladium can invert the selectivity of oxidative addition
Elias, Emily K.,Neufeldt, Sharon R.,Rehbein, Steven M.
, p. 1618 - 1628 (2022/02/21)
Reaction solvent was previously shown to influence the selectivity of Pd/PtBu3-catalyzed Suzuki-Miyaura cross-couplings of chloroaryl triflates. The role of solvents has been hypothesized to relate to their polarity, whereby polar solvents stabilize anionic transition states involving [Pd(PtBu3)(X)]- (X = anionic ligand) and nonpolar solvents do not. However, here we report detailed studies that reveal a more complicated mechanistic picture. In particular, these results suggest that the selectivity change observed in certain solvents is primarily due to solvent coordination to palladium. Polar coordinating and polar noncoordinating solvents lead to dramatically different selectivity. In coordinating solvents, preferential reaction at triflate is likely catalyzed by Pd(PtBu3)(solv), whereas noncoordinating solvents lead to reaction at chloride through monoligated Pd(PtBu3). The role of solvent coordination is supported by stoichiometric oxidative addition experiments, density functional theory (DFT) calculations, and catalytic cross-coupling studies. Additional results suggest that anionic [Pd(PtBu3)(X)]- is also relevant to triflate selectivity in certain scenarios, particularly when halide anions are available in high concentrations.
