98-89-5Relevant articles and documents
Palladium and copper-catalyzed carboxylation of alkanes with carbon monoxide. Remarkable effect of the mixed metal salts
Nakata,Miyata,Jintoku,Kitani,Taniguchi,Takaki,Fujiwara
, p. 3755 - 3759 (1993)
The mixed catalyst Pd(OAc)2-Cu(OAc)2 promotes the carboxylation of cyclohexane and propane with CO in higher yield than either a Pd(II) or Cu(II) catalyst alone. The mixed catalyst has the highest activity when the ratio of Cu(II)/Pd(II) is more than unity. The carboxylations of p-xylene with Pd(II)-Cu(II) and Pd(II) afford 2,5-dimethylbenzoic acid, but no carboxylic acid is detected in the reaction with Cu(II), giving rise to p- xylene dimer as the major product instead. Clear isotope effect (3.0-3.2) is observed in the reactions of cyclohexane with Pd(II)-Cu(II) and Pd(II), unlike the reaction with Cu(II) (1.0).
Ring hydrogenation of aromatic compounds in aqueous suspensions of an Rh-loaded TiO2 photocatalyst without use of H2 gas
Nakanishi, Kousuke,Yagi, Ryosuke,Imamura, Kazuya,Tanaka, Atsuhiro,Hashimoto, Keiji,Kominami, Hiroshi
, p. 139 - 146 (2018)
There are various possibilities of co-catalyst-assisted photocatalytic reduction (CPR) over a titanium(iv) oxide (TiO2) photocatalyst, especially H2-free and chemoselective CPR. We examined the photoinduced ring hydrogenation of aromatics having a carboxyl group over metal-loaded TiO2 under H2-free conditions and found that the aromatics were almost quantitatively hydrogenated to the corresponding cyclohexanes having a carboxyl group when rhodium, water and oxalic acid were used as a metal co-catalyst, solvent and hole scavenger, respectively. The effects of different metal co-catalysts, solvents and hole scavengers on the ring hydrogenation were also examined. Based on the results obtained under various conditions, the light dependency and adsorption behavior of the aromatics and hole scavengers, the functions of TiO2 and the co-catalyst, and the reaction process are discussed.
Palladium Catalyzed Carboxylation of Cyclohexane with Carbon Monoxide
Nakata, Kazuyuki,Watanabe, Jun,Takaki, Ken,Fujiwara, Yuzo
, p. 1437 - 1438 (1991)
Very high turnover numbers of the catalyst in direct carboxylation of cyclohexane with CO have been obtained using palladium catalyst, to give 8.8percent yield (turnover number 205) of cyclohexanecarboxylic acid based on the starting alkane.
Boosting Catalysis of Pd Nanoparticles in MOFs by Pore Wall Engineering: The Roles of Electron Transfer and Adsorption Energy
Chen, Dongxiao,Yang, Weijie,Jiao, Long,Li, Luyan,Yu, Shu-Hong,Jiang, Hai-Long
, (2020)
The chemical environment of metal nanoparticles (NPs) possesses significant influence on their catalytic performance yet is far from being well understood. Herein, tiny Pd NPs are encapsulated into the pore space of metal–organic frameworks (MOFs), UiO-66-X (X = H, OMe, NH2, 2OH, 2OH(Hf)), affording Pd@UiO-66-X composites. The surface microenvironment of the Pd NPs is readily modulated by pore wall engineering, via the functional group and metal substitution in the MOFs. Consequently, the catalytic activity of Pd@UiO-66-X follows the order of Pd@UiO-66-OH > Pd@UiO-66-2OH(Hf) > Pd@UiO-66-NH2 > Pd@UiO-66-OMe > Pd@UiO-66-H toward the hydrogenation of benzoic acid. It is found that the activity difference is not only ascribed to the distinct charge transfer between Pd and the MOF, but is also explained by the discriminated substrate adsorption energy of Pd@UiO-66-X (–OH 2 –OMe –H), based on CO-diffuse reflectance infrared Fourier transform spectra and density-functional theory (DFT) calculations. The Pd@UiO-66-OH, featuring a high Pd electronic state and moderate adsorption energy, displays the highest activity. This work highlights the influence of the surface microenvironment of guest metal NPs, the catalytic activity of which is dominated by electron transfer and the adsorption energy, via the systematic substitution of metal and functional groups in host MOFs.
In-situ generated highly dispersed nickel nanoclusters confined in MgAl mixed metal oxide platelets for benzoic acid hydrogenation
Zhang, Huiling,Dong, Jie,Qiao, Xianliang,Qin, Jingru,Sun, Haofei,Wang, Aiqing,Niu, Libo,Bai, Guoyi
, p. 258 - 265 (2019)
A new and cost-effective NiMgAl mixed metal oxide (Ni2Mg0.5Al1-MMO) catalyst derived from hierarchical flower-like Ni-Mg-Al layered double hydroxides (NiMgAl-LDHs) was fabricated by a hydrothermal-calcination-reduction method. This catalyst showed excellent catalytic performance in the selective hydrogenation of benzoic acid to cyclohexanecarboxylic acid. Notably, recycling experiments demonstrated that this catalyst could be used at least ten times without significant losses in activity and selectivity under harsh reaction conditions; thus, it presents similar behavior to most of noble metal catalysts. A series of characterizations were performed to investigate the relationship between the structure and the catalytic performance of this catalyst and elucidate the mechanism of its good stability. The results demonstrated that the Ni2Mg0.5Al1-MMO catalyst exhibited highly dispersed nickel species due to the well-defined flower-like structure of NiMgAl-MMO platelets as well as the confined effect of Mg and Al oxide species.
Highly effective Ir-based catalysts for benzoic acid hydrogenation: Experiment- and theory-guided catalyst rational design
Tang, Minghui,Mao, Shanjun,Li, Xuefeng,Chen, Chunhong,Li, Mingming,Wang, Yong
, p. 1766 - 1774 (2017)
On the way to exploring superior hydrogenation catalysts, Ir-based catalysts with a record catalytic activity (up to 40 h-1) for the hydrogenation of benzoic acid to cyclohexanecarboxylic acid under mild reaction conditions (85 °C, 0.1 MPa H2, in water) have been successfully developed. By excluding various factors, the experimental results showed that the main factor governing the activity discrepancy between the Ir-based catalysts is actually the dispersion stability of the supports (such as N-doped carbon, active carbon, SBA-15 and various metal oxides) in the reaction solution, rather than the interaction between the Ir active component and the supports. Combined with theoretical investigation from first principles, an activity volcano curve considering the competing adsorption between the reactants (H2) and solvent (H2O) for aqueous aromatic ring hydrogenation was presented for the first time. The high activity of Ir can be deduced by the proper discrepancy of dissociation energies or adsorption energies between H2 and H2O on the catalysts. This activity volcano curve provides guidance for further rational design of promising catalysts for benzoic acid or even aromatic ring hydrogenation under true reaction conditions for practical applications.
RuPd alloy nanoparticles supported on N-doped carbon as an efficient and stable catalyst for benzoic acid hydrogenation
Tang, Minghui,Mao, Shanjun,Li, Mingming,Wei, Zhongzhe,Xu, Fan,Li, Haoran,Wang, Yong
, p. 3100 - 3107 (2015)
RuPd alloy nanoparticles (3.6 nm) uniformly dispersed on N-doped carbon (RuPd/CN) was prepared via a simple ultrasound-assisted coreduction method. The RuPd/CN is highly active, selective, and stable in the hydrogenation of benzoic acid to cyclohexanecarboxylic acid under mild conditions with a TOF up to 2066 h-1. It was found that the bimetallic RuPd/CN catalyst exhibited a substantially enhanced activity in comparison with the monometallic catalysts (Ru/CN and Pd/CN). The reason for the higher performance of the RuPd/CN catalyst is considered to be the increased Ru0 /Run+ ratio induced by the electronic interaction between Ru and Pd, as evidenced by various characterizations. Notably, the different phenomenon of activity platform on different catalysts ascribed to the effect of hydrogen pressure was newly observed and further explained by first-principle studies. Moreover, the factors influencing the adsorption modes of BA, especially the configuration of the carboxyl group, have been investigated preliminarily in first-principle studies, giving a distinct insight from the former work. The reason the carboxyl group in benzoic acid does not undergo hydrogenation, which results in superior selectivity (>99%), is also revealed by a comparison of the thermodynamics of hydrogenation and dissociation of the carboxyl group.
A highly dispersed and stable Ni/mSiO2-AE nanocatalyst for benzoic acid hydrogenation
Zhang, Huiling,Gao, Xuejia,Ma, Yuanyuan,Han, Xue,Niu, Libo,Bai, Guoyi
, p. 5993 - 5999 (2017)
A Ni/mSiO2-AE nanocatalyst was successfully prepared via loading the active nickel species on mSiO2 by an ammonia evaporation (AE) method. It exhibited excellent catalytic performance in the selective hydrogenation of benzoic acid with the conversion of benzoic acid and selectivity to cyclohexane carboxylic acid being 98.9% and 99.1%, respectively. Furthermore, the catalyst can be recycled four times without appreciable loss of its initial activity. As demonstrated by TEM, the active nickel species was highly dispersed with an average particle size of 3.2 nm in this nanocatalyst, which is much smaller than that of Ni/mSiO2-IMP (～18 nm), prepared by a conventional impregnation method. TPR and XPS results revealed the existence of a stronger interaction between the active nickel species and the mSiO2 support in Ni/mSiO2-AE, compared to Ni/mSiO2-IMP. This strong metal-support interaction in Ni/mSiO2-AE can effectively suppress the loss of the active nickel species during the reaction, resulting in its good stability under relatively harsh reaction conditions.
Transformation of Thioacids into Carboxylic Acids via a Visible-Light-Promoted Atomic Substitution Process
Fu, Qiang,Liang, Fu-Shun,Lou, Da-Wei,Pan, Gao-Feng,Wang, Rui,Wu, Min,Xie, Kai-Jun
, p. 2020 - 2024 (2022/03/31)
A visible-light-promoted atomic substitution reaction for transforming thiocacids into carboxylic acids with dimethyl sulfoxide (DMSO) as the oxygen source has been developed, affording various alkyl and aryl carboxylic acids in over 90% yields. The atomic substitution process proceeds smoothly through the photochemical reactivity of the formed hydrogen-bonding adduct between thioacids and DMSO. A DMSO-involved proton-coupled electron transfer (PCET) and the simultaneous generation of thiyl and hydroxyl radicals are proposed to be key steps for realizing the transformation.
Synthesis of β-nitro ketones from geminal bromonitroalkanes and silyl enol ethers by visible light photoredox catalysis
Cao, Haoying,Ma, Shanshan,Feng, Yanhong,Guo, Yawen,Jiao, Peng
supporting information, p. 1780 - 1783 (2022/02/17)
Various β-nitro ketones, including those bearing a β-tertiary carbon, were prepared from geminal bromonitroalkanes and trimethylsilyl enol ethers of a broad range of ketones by visible light photoredox catalysis, which were then easily converted into β-amino ketones, 1,3-amino alcohols, α,β-unsaturated ketones, β-cyano ketones and γ-nitro ketones.
