626-93-7Relevant articles and documents
Zirconium Oxide Supported Palladium Nanoparticles as a Highly Efficient Catalyst in the Hydrogenation–Amination of Levulinic Acid to Pyrrolidones
Zhang, Jian,Xie, Bin,Wang, Liang,Yi, Xianfeng,Wang, Chengtao,Wang, Guoxiong,Dai, Zhifeng,Zheng, Anmin,Xiao, Feng-Shou
, p. 2661 - 2667 (2017)
The selective hydrogenation–amination of levulinic acid into pyrrolidones is regarded as one of the most important reactions to transform biomass-derived lignocellulose feedstocks into valuable chemicals. Here we report on ZrO2-supported Pd nanoparticles as a highly active, chemoselective, and reusable catalyst for the hydrogenation–amination of levulinic acid with H2 and various amines under mild reaction conditions. The Pd/ZrO2 catalyst exhibited a marked increase in activity compared with conventional Pd catalysts and a significant enhancement in pyrrolidone selectivity. The excellent catalytic performances are reasonably attributed to the ZrO2 support, which has strong Lewis acidity to enhance the hydrogenation–amination reaction and hinder side reactions.
IVESTIGATIONS OF THE MECHANISM OF THE Rh/Cu- AND Rh-CATALYZED OXIDATION OF TERMINAL OLEFINS WITH O2
Drago, Russell S.,Zuzich, Anne,Nyberg, Eric D.
, p. 2898 - 2903 (1985)
The mechanism of the Rh(III9-catalyzed oxidation of 1-hexene to 2-hexanone, both with and without a Cu(II) co-catalyst, is investigated.In the absence of Cu(II), only one oxygen atom of dioxygen is found to be incorporated into ketone product.This contrasts with the previously reported observation that in the presence of the Cu(II) co-catalyst both oxygen atoms of O2 are incorporated into product.Similaly, the Rh(III) catalyst without Cu(II) isomerizes 1-hexene to a large extent, in contrast to the previously reported Rh/Cu catalyst system.Both acetone and water are found to be produced continously when isopropyl alcohol is the absence of Cu(II), while neither are formed continuosly when Cu(II) is present.Furthermore, itis shown that H"O" and t-BuOOH may be used as the 1-hexene oxidant under anaerobic conditions in the presence or absence of Cu(II), producing 2-ketone.These observations are incorporated into tentative mechanisms which specify key roles for copper that lead to differences in reactivity.
A Cyclometalated NHC Iridium Complex Bearing a Cationic (η5-Cyclopentadienyl)(η6-phenyl)iron Backbone**
Malchau, Christian,Milbert, Tom,Eger, Tobias R.,Fries, Daniela V.,Pape, Pascal J.,Oelkers, Benjamin,Sun, Yu,Becker, Sabine,Prosenc, Marc H.,Niedner-Schatteburg, Gereon,Thiel, Werner R.
, p. 15208 - 15216 (2021)
Nucleophilic substitution of [(η5-cyclopentadienyl)(η6-chlorobenzene)iron(II)] hexafluorophosphate with sodium imidazolate resulted in the formation of [(η5-cyclopentadienyl)(η6-phenyl)iron(II)]imidazole hexafluorophosphate. The corresponding dicationic imidazolium salt, which was obtained by treating this imidazole precursor with methyl iodide, underwent cyclometallation with bis[dichlorido(η5-1,2,3,4,5-pentamethylcyclopentadienyl]iridium(III) in the presence of triethyl amine. The resulting bimetallic iridium(III) complex is the first example of an NHC complex bearing a cationic and cyclometallated [(η5-cyclopentadienyl)(η6-phenyl)iron(II)]+ substituent. As its iron(II) precursors, the bimetallic iridium(III) complex was fully characterized by means of spectroscopy, elemental analysis and single crystal X-ray diffraction. In addition, it was investigated in a catalytic study, wherein it showed high activity in transfer hydrogenation compared to its neutral analogue having a simple phenyl instead of a cationic [(η5-cyclopentadienyl)(η6-phenyl)iron(II)]+ unit at the NHC ligand.
Organozirconium Complex with Keggin-Type Mono-Aluminum-Substituted Silicotungstate: Synthesis, Molecular Structure, and Catalytic Performance for Meerwein–Ponndorf–Verley Reduction
Kato, Chika Nozaki,Unno, Wataru,Kato, Sakie,Ogasawara, Tsukasa,Kashiwagi, Toshifumi,Uno, Hidemitsu,Suzuki, Kosuke,Mizuno, Noritaka
, p. 2119 - 2128 (2016)
Abstract: The organozirconium complex with α-Keggin-type mono-aluminum-substituted silicotungstate, [(n-C4H9)4N]6[α-SiW11Al(OH)2O38ZrCp2]2·2H2O (TBA–Si–Al–Zr) was synthesized by the reaction of Cp2Zr(OTf)2·THF (or Cp2ZrCl2) with [(n-C4H9)4N]4K0.5H0.5[α-SiW11{Al(OH2)}O39]·H2O in acetonitrile. This compound showed high catalytic activities for Meerwein–Ponndorf–Verley reduction of ketones with 2-propanol in both homogeneous and heterogeneous system. Graphical Abstract: [Figure not available: see fulltext.]
Regiodivergent Reductive Opening of Epoxides by Catalytic Hydrogenation Promoted by a (Cyclopentadienone)iron Complex
De Vries, Johannes G.,Gandini, Tommaso,Gennari, Cesare,Jiao, Haijun,Pignataro, Luca,Stadler, Bernhard M.,Tadiello, Laura,Tin, Sergey
, p. 235 - 246 (2022/01/03)
The reductive opening of epoxides represents an attractive method for the synthesis of alcohols, but its potential application is limited by the use of stoichiometric amounts of metal hydride reducing agents (e.g., LiAlH4). For this reason, the corresponding homogeneous catalytic version with H2 is receiving increasing attention. However, investigation of this alternative has just begun, and several issues are still present, such as the use of noble metals/expensive ligands, high catalytic loading, and poor regioselectivity. Herein, we describe the use of a cheap and easy-To-handle (cyclopentadienone)iron complex (1a), previously developed by some of us, as a precatalyst for the reductive opening of epoxides with H2. While aryl epoxides smoothly reacted to afford linear alcohols, aliphatic epoxides turned out to be particularly challenging, requiring the presence of a Lewis acid cocatalyst. Remarkably, we found that it is possible to steer the regioselectivity with a careful choice of Lewis acid. A series of deuterium labeling and computational studies were run to investigate the reaction mechanism, which seems to involve more than a single pathway.
A novel and efficient N-doping carbon supported cobalt catalyst derived from the fermentation broth solid waste for the hydrogenation of ketones via Meerwein–Ponndorf–Verley reaction
Chen, Yuxin,He, Runxia,Liu, Quansheng,Yao, Xuefeng,Zhou, Huacong
, (2021/12/10)
Most of the non-noble metal catalysts used for the Meerwein–Ponndorf–Verley (MPV) reaction of carbonyl compounds rely on the additional alkaline additives during preparation to achieve high efficiency. To solve this problem, in this work, we prepared a novel N-doped carbon supported cobalt catalyst (Co@CN), in which the carriers were derived from the nitrogen-rich organic waste, i.e., oxytetracycline fermentation residue (OFR, obtained from oxytetracycline refining workshop). No additional nitrogen sources were used during preparation. The results showed that inherent nitrogen in OFR could provide N-containing basic sites, and formed Co-N structures via coordinating with cobalt. The Co-N sites together with the coexisting Co(0) cooperated to catalyze the conversion of ethyl levulinate (EL) to γ-valerolactone (GVL) by MPV reaction. Co(0) dominated the activation of H in isopropanol, while Co-N dominated the formation of the six-membered ring transition state.
Synthesis of TS-1 zeolites from a polymer containing titanium and silicon
Xing, Jiacheng,Yuan, Danhua,Liu, Hanbang,Tong, Yansi,Xu, Yunpeng,Liu, Zhongmin
, p. 6205 - 6213 (2021/03/22)
The synthesis of TS-1 zeolites is regarded as a milestone in zeolite history, and it has led to the revolution of the green oxidation system of using H2O2as an oxidant, leaving only water as the byproduct. However, because of the highly hydrolyzable titanium source, the preparation of TS-1 requires complex synthesis conditions. Moreover, the difference in the hydrolysis rate between the silicon source and titanium source tends to increase the difficulty of titanium insertion into the framework, and it is easy to generate extra-framework Ti species during the synthesis. Here, a high-quality TS-1 zeolite with a large external surface area and free of extra-framework Ti species has been successfully synthesized by using a kind of novel polymer containing titanium and silicon. Due to the high hydrolysis resistance of the polymer reagent, a good matching of the hydrolysis rate between the silicon source and the titanium source is realized during crystallization, which facilitates the incorporation of titanium into the framework. Furthermore, the TS-1 zeolite exhibited excellent catalytic performance inn-hexane oxidation with hydrogen peroxide as the oxidant. This method of synthesizing zeolites from polymers is expected to be widely applied for the synthesis of other titanium-containing zeotype materials.
Chromium-Catalyzed Production of Diols From Olefins
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Paragraph 0111, (2021/03/19)
Processes for converting an olefin reactant into a diol compound are disclosed, and these processes include the steps of contacting the olefin reactant and a supported chromium catalyst comprising chromium in a hexavalent oxidation state to reduce at least a portion of the supported chromium catalyst to form a reduced chromium catalyst, and hydrolyzing the reduced chromium catalyst to form a reaction product comprising the diol compound. While being contacted, the olefin reactant and the supported chromium catalyst can be irradiated with a light beam at a wavelength in the UV-visible spectrum. Optionally, these processes can further comprise a step of calcining at least a portion of the reduced chromium catalyst to regenerate the supported chromium catalyst.
Facile gas-phase hydrodeoxygenation of 2,5-dimethylfuran over bifunctional metal-acid catalyst Pt-Cs2.5H0.5PW12O40
Althikrallah, Hanan,Kozhevnikova, Elena F.,Kozhevnikov, Ivan V.
supporting information, p. 227 - 230 (2021/01/14)
2,5-Dimethylfuran is deoxygenated to n-hexane with 100% yield on a bifunctional Pt/C-Cs2.5H0.5PW12O40 catalyst under very mild conditions (90 °C, 1 bar H2) in a one-step gas-phase process. A proposed mechanism includes a sequence of hydrogenolysis, hydrogenation and dehydration steps occurring on Pt and proton sites of the bifunctional catalyst.
Direct Visualization of Substitutional Li Doping in Supported Pt Nanoparticles and Their Ultra-selective Catalytic Hydrogenation Performance
Chen, Tianyi,Foo, Christopher,Zheng, Jianwei J. W.,Fang, Huihuang,Nellist, Peter,Tsang, Shik Chi Edman
supporting information, p. 12041 - 12046 (2021/07/14)
It has only recently been established that doping light elements (lithium, boron, and carbon) into supported transition metals can fill interstitial sites, which can be observed by the expanded unit cell. As an example, interstitial lithium (intLi) can block H filling octahedral interstices of palladium metal lattice, which improves partial hydrogenation of alkynes to alkenes under hydrogen. In contrast, herein, we report intLi is not found in the case of Pt/C. Instead, we observe for the first time a direct ‘substitution’ of Pt with substitutional lithium (subLi) in alternating atomic columns using scanning transmission electron microscopy-annular dark field (STEM-ADF). This ordered substitutional doping results in a contraction of the unit cell as shown by high-quality synchrotron X-ray diffraction (SXRD). The electron donation of d-band of Pt without higher orbital hybridizations by subLi offers an alternative way for ultra-selectivity in catalytic hydrogenation of carbonyl compounds by suppressing the facile CO bond breakage that would form alcohols.
