2305-21-7Relevant academic research and scientific papers
The selective hydrogenation of furfural over intermetallic compounds with outstanding catalytic performance
Yang, Yusen,Chen, Lifang,Chen, Yudi,Liu, Wei,Feng, Haisong,Wang, Bin,Zhang, Xin,Wei, Min
, p. 5352 - 5362 (2019)
The selective hydrogenation of furfural (a biomass-derived platform compound, CO versus CC) is an important reaction for the production of chemical intermediates widely used in the polymer industry. Herein, we report three non-precious intermetallic compounds (IMCs) (Ni3Sn1, Ni3Sn2 and Ni3Sn4) derived from a layered double hydroxide (LDH) precursor, which are characterized by a highly uniform dispersion of IMC nanoparticles and display surprisingly improved catalytic performance toward the selective hydrogenation of furfural (CO) to furfuryl alcohol. In particular, the Ni3Sn2 IMC shows optimal catalytic behavior (conversion: 100%; selectivity: 99%), which exceeds that of reported non-precious metal catalysts and is even comparable to that of noble metal catalysts (e.g., Au, Pd and Pt). A combinative investigation based on in situ FT-IR, XANES and Bader charge studies verifies electron transfer from Sn to Ni, facilitating the activation of adsorption of the CO bond on the Ni top site, whilst inhibiting the adsorption of CC. Both experimental studies (in situ FT-IR and catalytic evaluations) and theoretical calculations (DFT calculations and microkinetic modeling) reveal a vertical adsorption configuration of furfural molecules over the Ni3Sn2 IMC, followed by the first hydrogenation at the carbon atom (the rate-determining step) and the second hydrogenation at the oxygen atom. This detailed study of the structure-selectivity relationship is substantiated by virtue of establishing the adsorption configuration of the substrate and the reaction pathway, which paves the way for the rational design and development of high-efficiency heterogeneous catalysts for selective hydrogenation reactions.
An iridium-SPO complex as bifunctional catalyst for the highly selective hydrogenation of aldehydes
Cano, Israel,Martínez-Prieto, Luis M.,Vendier, Laure,Van Leeuwen, Piet W. N. M.
, p. 221 - 228 (2018)
A secondary phosphine oxide (SPO) ligand (tert-butyl(phenyl)phosphine oxide) was employed to generate an Ir-SPO complex which shows a particular ability to activate dihydrogen under mild conditions without the help of an external base or additive. Such an iridium(i) complex serves as a precursor for homogeneous catalysis since under H2 it is converted to a mixture of several iridium(iii) hydride species that are the active catalysts. This system was found to be a highly active catalyst for the hydrogenation of substituted aldehydes, giving very high conversions and chemoselectivities for a wide range of substrates. The SPO ligand presumably plays a key role in the catalytic process through heterolytic cleavage of H2 by metal-ligand cooperation. In addition, an exhaustive characterization of the different iridium hydride species was performed by 1D and 2D NMR spectroscopy. The oxidative addition of H2 to the Ir(i)-SPO complex is highly stereoselective, as all generated Ir(iii) hydrides are homochiral. Finally, the crystal structure, as determined by X-ray diffraction, of a dinuclear iridium(iii) hydride complex is described.
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.
Efficient and chemoselective hydrogenation of aldehydes catalyzed by well-defined PN3-pincer manganese(ii) catalyst precursors: An application in furfural conversion
Gholap, Sandeep Suryabhan,Dakhil, Abdullah Al,Chakraborty, Priyanka,Li, Huaifeng,Dutta, Indranil,Das, Pradip K.,Huang, Kuo-Wei
supporting information, p. 11815 - 11818 (2021/11/30)
Well-defined and air-stable PN3-pincer manganese(ii) complexes were synthesized and used for the hydrogenation of aldehydes into alcohols under mild conditions using MeOH as a solvent. This protocol is applicable for a wide range of aldehydes containing various functional groups. Importantly, α,β-unsaturated aldehydes, including ynals, are hydrogenated with the CC double bond/CC triple bond intact. Our methodology was demonstrated for the conversion of biomass derived feedstocks such as furfural and 5-formylfurfural to furfuryl alcohol and 5-(hydroxymethyl)furfuryl alcohol respectively.
A Construction of α-Alkenyl Lactones via Reduction Radical Cascade Reaction of Allyl Alcohols and Acetylenic Acids
Zhang, Hua,Zhang, Guo-Min,He, Shuai,Shi, Zhi-Chuan,Zhang, Xiao-Mei,Wang, Ji-Yu
supporting information, p. 8337 - 8344 (2020/11/03)
An iron-catalyzed cascade reaction of radical reduction of allyl alcohols and acetylenic acids to construct polysubstituted α-alkenyl lactones has been developed. In this paper, various allyl alcohols can form allyl ester intermediates and are further transformed into alkyl radicals, which form products through intramolecular reflex-Michael addition. In addition, this method can be used to prepare spirocycloalkenyl lactones. Interestingly, this protocol can be used to synthesize the skeleton structure of natural products. Moreover, the product can be further transformed into a β-methylene tetrahydrofuran and tetrahydrofuran diene.
The formyloxyl radical: Electrophilicity, C-H bond activation and anti-Markovnikov selectivity in the oxidation of aliphatic alkenes
Iron, Mark A.,Khenkin, Alexander M.,Neumann, Ronny,Somekh, Miriam
, p. 11584 - 11591 (2020/11/23)
In the past the formyloxyl radical, HC(O)O, had only been rarely experimentally observed, and those studies were theoretical-spectroscopic in the context of electronic structure. The absence of a convenient method for the preparation of the formyloxyl radical has precluded investigations into its reactivity towards organic substrates. Very recently, we discovered that HC(O)O is formed in the anodic electrochemical oxidation of formic acid/lithium formate. Using a [CoIIIW12O40]5- polyanion catalyst, this led to the formation of phenyl formate from benzene. Here, we present our studies into the reactivity of electrochemically in situ generated HC(O)O with organic substrates. Reactions with benzene and a selection of substituted derivatives showed that HC(O)O is mildly electrophilic according to both experimentally and computationally derived Hammett linear free energy relationships. The reactions of HC(O)O with terminal alkenes significantly favor anti-Markovnikov oxidations yielding the corresponding aldehyde as the major product as well as further oxidation products. Analysis of plausible reaction pathways using 1-hexene as a representative substrate favored the likelihood of hydrogen abstraction from the allylic C-H bond forming a hexallyl radical followed by strongly preferred further attack of a second HC(O)O radical at the C1 position. Further oxidation products are surmised to be mostly a result of two consecutive addition reactions of HC(O)O to the CC double bond. An outer-sphere electron transfer between the formyloxyl radical donor and the [CoIIIW12O40]5- polyanion acceptor forming a donor-acceptor [D+-A-] complex is proposed to induce the observed anti-Markovnikov selectivity. Finally, the overall reactivity of HC(O)O towards hydrogen abstraction was evaluated using additional substrates. Alkanes were only slightly reactive, while the reactions of alkylarenes showed that aromatic substitution on the ring competes with C-H bond activation at the benzylic position. C-H bonds with bond dissociation energies (BDE) ≤ 85 kcal mol-1 are easily attacked by HC(O)O and reactivity appears to be significant for C-H bonds with a BDE of up to 90 kcal mol-1. In summary, this research identifies the reactivity of HC(O)O towards radical electrophilic substitution of arenes, anti-Markovnikov type oxidation of terminal alkenes, and indirectly defines the activity of HC(O)O towards C-H bond activation.
Hafnium trifluoromethanesulfonate catalyzed silyl ether protecting group removing method
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Paragraph 0009; 0014, (2019/01/21)
The invention provides a hafnium trifluoromethanesulfonate catalyzed silyl ether protecting group removing method. Various silyl ether protecting groups of nearly 50 kinds of substrates can be efficiently removed in 0.5-16 hours at room temperature by taking 0.02mol%-0.3mol% hafnium trifluoromethanesulfonate as a catalyst, a silyl ether protected hydroxyl compound as a substrate and conventional AR methanol as a solvent. 42 kinds of silyl ether protecting group removing products can be obtained at high yield by performing conventional slica column chromatography purification on a crude product. By regulating the use amount of the catalyst, the Hf(OTf)4 catalyst can realize regioselective removal of 1-degree, 2-degree and 3-degree alkyl TBS and aryl TBS protective groups. Moreover, in a proper equivalent scope, the Hf(OTf)4 catalyst can also realize 1) chemoselective removal of different kinds of silica-based protective groups; and 2) chemoselective removal of 1-degree TBS protective groups under the condition of not affecting a majority of common hydroxyl protective groups.
Development of a novel secondary phosphine oxide-ruthenium(II) catalyst and its application for carbonyl reduction
Tan, Xuefeng,Zeng, Weijun,Zhang, Xiaoyong,Chung, Lung Wa,Zhang, Xumu
supporting information, p. 535 - 538 (2018/01/19)
A secondary phosphine oxide-phosphine mixed tridentate ligand and its ruthenium complex have been developed. This complex shows excellent catalytic activity for carbonyl reduction, especially for the reduction of α,β-unsaturated aldehydes. The turnover number and selectivity can reach up to 36500 and 99%, respectively. Control experiments and DFT calculations supported an outer-sphere mechanism during the hydrogenation reaction.
Selective Base-free Transfer Hydrogenation of α,β-Unsaturated Carbonyl Compounds using iPrOH or EtOH as Hydrogen Source
Farrar-Tobar, Ronald A.,Wei, Zhihong,Jiao, Haijun,Hinze, Sandra,de Vries, Johannes G.
supporting information, p. 2725 - 2734 (2018/02/28)
Commercially available Ru-MACHOTM-BH is an active catalyst for the hydrogenation of several functional groups and for the dehydrogenation of alcohols. Herein, we report on the new application of this catalyst to the base-free transfer hydrogenation of carbonyl compounds. Ru-MACHOTM-BH proved to be highly active and selective in this transformation, even with α,β-unsaturated carbonyl compounds as substrates. The corresponding aliphatic, aromatic and allylic alcohols were obtained in excellent yields with catalyst loadings as low as 0.1–0.5 mol % at mild temperatures after very short reaction times. This protocol tolerates iPrOH and EtOH as hydrogen sources. Additionally, scale up to multi-gram amounts was performed without any loss of activity or selectivity. An outer-sphere mechanism has been proposed and the computed kinetics and thermodynamics of crotonaldehyde and 1-phenyl-but-2-en-one are in perfect agreement with the experiment.
Porous, Naturally Derived Hafnium Phytate for the Highly Chemoselective Transfer Hydrogenation of Aldehydes with Other Reducible Moieties
Song, Jinliang,Xue, Zhimin,Xie, Chao,Wu, Haoran,Liu, Shuaishuai,Zhang, Lujun,Han, Buxing
, p. 725 - 730 (2018/01/22)
Both the utilization of naturally occurring compounds to prepare functional materials and the selective conversion of aldehydes with other reducible moieties (ORMs) are very attractive topics. Herein, we synthesized a novel porous material, hafnium phytate (Hf-Phy), by using naturally derived sodium phytate as the building block. Hf-Phy has plenty of mesopores centered around 11.8 nm. Hf-Phy showed excellent performance for the transfer hydrogenation of aldehydes with ORMs by using 2-propanol as the hydrogen source with high selectivities (95–100 %) for alcohols without reducing ORMs. Systematic studies suggested that the oxophilicity of Hf4+ and the basicity and structure of Hf-Phy contributed significantly to the excellent performance. Additionally, Hf-Phy could be used over at least five cycles without any decrease in activity or selectivity.
