- Oxyfunctionalization of Alkanes with H2O2 catalysed by Vanadium Silicates
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Vanadium silicate molecular sieves can catalyse the oxyfunctionalization of alkanes to corresponding alcohols, aldehydes and ketones; they are able to oxidise the primary carbon atom as well.
- Rao, P. R. Hari Prasad,Ramaswamy, A. V.
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- Highly Efficient Photocatalytic Degradation of Dyes by a Copper–Triazolate Metal–Organic Framework
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A copper(I) 3,5-diphenyltriazolate metal–organic framework (CuTz-1) was synthesized and extensively characterized by using a multi-technique approach. The combined results provided solid evidence that CuTz-1 features an unprecedented Cu5tz6 cluster as the secondary building unit (SBU) with channels approximately 8.3 ? in diameter. This metal–organic framework (MOF) material, which is both thermally and chemically (basic and acidic) stable, exhibited semiconductivity and high photocatalytic activity towards the degradation of dyes in the presence of H2O2. Its catalytic performance was superior to that of reported MOFs and comparable to some composites, which has been attributed to its high efficiency in generating .OH, the most active species for the degradation of dyes. It is suggested that the photogenerated holes are trapped by CuI, which yields CuII, the latter of which behaves as a catalyst for a Fenton-like reaction to produce an excess amount of .OH in addition to that formed through the scavenging of photogenerated electrons by H2O2. Furthermore, it was shown that a dye mixture (methyl orange, methyl blue, methylene blue, and rhodamine B) could be totally decolorized by using CuTz-1 as a photocatalyst in the presence of H2O2 under the irradiation of a Xe lamp or natural sunlight.
- Liu, Chen-Xia,Zhang, Wen-Hua,Wang, Nan,Guo, Penghu,Muhler, Martin,Wang, Yuemin,Lin, Shiru,Chen, Zhongfang,Yang, Guang
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- Interfacial Sites in Ag Supported Layered Double Oxide for Dehydrogenation Coupling of Ethanol to n-Butanol
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Upgrading of ethanol to n-butanol through dehydrogenation coupling has received increasing attention due to the wide application of n-butanol. But the enhancement of ethanol dehydrogenation and followed coupling to produce high selectivity to n-butanol is still highly desired. Our previous work has reported an acid-base-Ag synergistic catalysis, with Ag particles supported on Mg and Al-containing layered double oxides (Ag/MgAl-LDO). Here, Ag-LDO interfaces have been manipulated for dehydrogenation coupling of ethanol to n-butanol by tailoring the size of Ag particles and the interactions between Ag and LDO. It has been revealed that increasing the population of surface Ag sites at Ag-LDO interfaces promotes not only the dehydrogenation of ethanol to acetaldehyde but also the subsequent aldol condensation of generated acetaldehyde. A selectivity of up to 76 % to n-butanol with an ethanol conversion of 44 % has been achieved on Ag/LDO with abundant interfacial Ag sites, much superior to the state-of-the-art catalysts.
- Zhang, Jian,Shi, Kai,Zhu, Yanru,An, Zhe,Wang, Wanning,Ma, Xiaodan,Shu, Xin,Song, Hongyan,Xiang, Xu,He, Jing
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- New selectivities from old catalysts. Occlusion of Grubbs' catalysts in PDMS to change their reactions
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This article describes new selectivities for Grubbs' first and second generation catalysts when occluded in a hydrophobic matrix of polydimethylsiloxane (PDMS). Occlusion of catalysts in mm-sized slabs of PDMS is accomplished by swelling with methylene chloride then removing the solvent under vacuum. The catalysts are homogenously dissolved in PDMS yet remain catalytically active. Many substrates that react by olefin metathesis with Grubbs' catalysts freely dissolved in methylene chloride also react by olefin isomerization with occluded catalysts. Eleven examples of substrates that exhibit dual reactivity by undergoing olefin isomerization with occluded catalysts and olefin metathesis with catalysts dissolved in methylene chloride are reported. Most of these substrates have olefins with allylic phosphine oxides, carbonyls, or ethers. Control experiments demonstrate that isomerization is occurring in the solvent by decomposition of the catalyst from a ruthenium carbene to a proposed ruthenium hydride. This work was extended by heating occluded Grubbs' first generation catalyst to 100 °C in 90% MeOH in H2O in the presence of various alkenes to transform the Grubbs' catalyst into an isomerization catalyst for unfunctionalized olefins. This work demonstrates that occlusion of organometallic catalysts in PDMS has important implications for their reactions and can be used as a method to control which reactions they catalyze.
- Brett Runge,Mwangi, Martin T.,Bowden, Ned B.
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- Thermal desulfurization of (Alkoxymethyl)thiiranes
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Reaction of (alkoxymethyl)oxiranes with thiourea in methanol has afforded the corresponding thiiranes, and catalyst-free thermal desulfurization of the products has been studied. The major products of desulfurization are alcohols and alkenes, both in the cases of (polyfluoroalkyloxymethyl)thiiranes and their non-fluorinated analogs. Longer alkyl chain in thiiranes favors formation of alcohols over alkenes formation in the course of desulfurization.
- Nalet'Ko,Pervova,Gorbunova,Zapevalov, A. Ya,Toporova,Saloutin
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- Mechanistic study of the selective hydrogenation of carboxylic acid derivatives over supported rhenium catalysts
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The structure and performance of TiO2-supported Re (Re/TiO2) catalysts for selective hydrogenation of carboxylic acid derivatives have been investigated. Re/TiO2 promotes selective hydrogenation reactions of carboxylic acids and esters that form the corresponding alcohols, and of amides that generate the corresponding amines. These processes are not accompanied by reduction of aromatic moieties. A Re loading amount of 5 wt% and a catalyst pretreatment with H2 at 500 °C were identified as being optimal to obtain the highest catalytic activity for the hydrogenation processes. The results of studies using various characterization methods, including X-ray diffraction (XRD), X-ray absorption fine structure (XAFS), X-ray photoelectron spectroscopy (XPS), and scanning transmission electron microscopy (STEM), indicate that the Re species responsible for the catalytic hydrogenation processes have sub-nanometer to a few nanometer sizes and average oxidation states higher than 0 and below +4. The presence of either a carboxylic acid and/or its corresponding alcohol is critical for preventing the Re/TiO2 catalyst from promoting production of dearomatized byproducts. Although Re/TiO2 is intrinsically capable of hydrogenating aromatic rings, carboxylic acids, alcohols, amides, and amines strongly adsorb on the Re species, which leads to suppression of this process. Moreover, the developed catalytic system was applied to selective hydrogenation of triglycerides that form the corresponding alcohols.
- Toyao, Takashi,Ting, Kah Wei,Siddiki, S. M. A. Hakim,Touchy, Abeda S.,Onodera, Wataru,Maeno, Zen,Ariga-Miwa, Hiroko,Kanda, Yasuharu,Asakura, Kiyotaka,Shimizu, Ken-ichi
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- Epoxidation of Alkenes with O2 Catalyzed by EuCl3 under Ambient Conditions
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EuCl3 dissolved in a mixture of propanoic acid and 1,2-dichloroethane catalyzed the epoxidation of 1-hexene (81.4percent selectivity, 5.34percent yield for 1h) with O2 in the presence of Zn powder at 40 deg C.The epoxidation was also catalyzed by LaCl3 (0.75percent yield) and SmCl3 (0.57percent yield), but CeCl3 (0.08percent yield) was inactive.Epoxidations of styrene and cyclohexene were also promoted by the EuCl3-catalytic system.
- Yamanaka, Ichiro,Nakagaki, Katsumi,Akimoto, Takashi,Otsuka, Kiyoshi
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- LiBH4-promoted Hydroboration of Alkenes with 1,3,2-Benzodioxaborole
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In the presence of a small amount of LiBH4 mono-, di-, tri- and tetr-substituted ethenes were hydroborated almost quantitatively with 1,3,2-benzodioxaborole (catecholborane) under very mild conditions.
- Arase, Akira,Nunokawa, Yutaka,Masuda, Yuzuru,Hoshi, Masayuki
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- Catalytic conversion of ethanol into an advanced biofuel: Unprecedented selectivity for n-butanol
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Taming the beast: Unprecedented selectivity of over 94 % at good (20 %+) conversion was observed for the upgrade of ethanol to the advanced biofuel 1-butanol with a ruthenium diphosphine catalyst (see picture; P orange, Ru blue). Preliminary mechanistic studies indicate that control over the notoriously uncontrolled acetaldehyde aldol condensation is critical for the high selectivity, and evidence was found for an on-metal condensation step. Copyright
- Dowson, George R. M.,Haddow, Mairi F.,Lee, Jason,Wingad, Richard L.,Wass, Duncan F.
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- Supported nickel-rhenium catalysts for selective hydrogenation of methyl esters to alcohols
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The addition of Re to Ni on TiO2 yields efficient catalysts for the hydrogenation of acids and esters to alcohols under mild conditions. Rhenium promotes the formation of atomically dispersed and sub-nanometre-sized bimetallic species interacting strongly with the oxide support.
- Liu, Kaituo,Pritchard, James,Lu, Li,Van Putten, Robbert,Verhoeven,Schmitkamp, Mike,Huang, Xiaoming,Lefort, Laurent,Kiely, Christopher J.,Hensen, Emiel J. M.,Pidko, Evgeny A.
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- Revised Mechanisms of the Catalytic Alcohol Dehydrogenation and Ester Reduction with the Milstein PNN Complex of Ruthenium
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The combined experimental/DFT computational study of RuH2(CO)[Et2NCH2PyCH2Pt-Bu2] (2) suggests that this dihydride is the catalyst of the acceptorless alcohol dehydrogenation and ester hydrogenation reactions developed in the group of Milstein, whereas the corresponding alkoxide RuH(OR)(CO)[Et2NCH2PyCH2Pt-Bu2] (4) is an important reaction intermediate. A relatively fast equilibrium of dihydride 2 and ethanol with ethoxide 4 and H2 was demonstrated by NMR experiments, as well as the proton exchanges occurring between the OH of ethanol, RuH, and the CH2 groups of the PNN ligand backbone of 2 and 4. A detailed critical discussion of the previously proposed mechanisms with the Milstein catalyst is presented. This paper also reports the preparation of the osmium dihydride OsH2(CO)[Et2NCH2PyCH2Pt-Bu2] (2-Os) and a comparative study of 2, 2-Os, and the Noyori-type osmium catalyst OsH2(CO)[PyCH2NHCH2CH2NHPt-Bu2].
- Gusev, Dmitry G.
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- A new route of the reaction of EtAlCl2 with α-olefins catalyzed by Ti complexes
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A new method for the synthesis of dialkyl(ethyl)alanes by the reaction of EtAlCl2 with α-olefins in the presence of Mg and a catalytic amount of Cp2TiCl2 (Ti(OPri)4, Ti(OBun)4) in THF was developed.
- Ibragimov,Khafizova,Zagrebel'naya,Parfenova,Sultanov,Khalilov,Dzkemilev
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- Catalytic upgrading of ethanol to butanol over a binary catalytic system of FeNiOx and LiOH
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Catalytic conversion of ethanol to butanol is vital to bridge the gap between huge amounts of ethanol production, the limited blending ratio of ethanol in gasoline, and the outstanding performance of butanol. In this work, a highly active binary catalytic system of FeNiOx and LiOH was developed for upgrading of ethanol to butanol. After 24 h reaction at 493 K, the selectivity to butanol reached 71% with >90% high carbon alcohols at 28% ethanol conversion, which was comparable to the performance of some noble metal homogeneous catalysts.
- Li, Xianquan,Li, Xinsheng,Liu, Shimin,Pang, Jifeng,Wang, Junhu,Wang, Zhinuo,Zhang, Tao,Zheng, Mingyuan
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- Enzymes inhibitory constituents from Buddleja crispa
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Steroidal galactoside 1 and aryl esters 2 and 3 have been isolated from Buddleja crispa, along with ginipin 4, gardiol 5, 1-heptacosanol 6, and methyl benzoate 7, isolated for the first time from this species. The structures of all of the compounds were determined by spectroscopic techniques and chemical studies. The steroidal galactoside 1 is an inhibitor of lipoxygenase. Compounds 1-3 displayed inhibitory activity against butyrylcholinesterse, while compounds 2 and 3 further showed inhibition against acetylcholinesterase.
- Ahmad, Ijaz,Malik, Abdul,Afza, Nighat,Anis, Itrat,Fatima, Itrat,Nawaz, Sarfraz Ahmad,Tareen, Rasool Bukhsh,Iqbal Choudhary
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- Reactivity of active oxygen species generated in the EuCl3 catalytic system for monooxygenation of hydrocarbons
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The reactivity of active oxygen species generated from O2 in the EuCl3-Zn-MeCO2H catalytic system for the monooxygenation of various hydrocarbons has been studied in detail. In the case of the oxygenation of alkanes, a large difference between the reactivities of primary, secondary and tertiary C-H bonds (1:6:19) is observed. The kinetic isotope effect (KIE) between C-H and C-D (2.6) for the oxidation of cyclohexane, the relative conversion rate of cooxidation of cyclopentane and cyclohexane (C5/C6 = 0.7) and the non-retention of the configuration of tertiary C-H bonds suggest that the cleavage of the C-H bond is a key step in forming the alkyl radical intermediate by H abstraction in the oxidation of alkanes. In the case of epoxidation of cis-hex-2-ene and trans-hex-2-ene, the cis- and trans-configurations are not preserved in their epoxides. This suggests that the epoxidation proceeds through alkyl radical intermediates. In the case of the hydroxylation of toluene, the regioselectivity in the formations of cresols (o:m:p, 13:1:16) suggests a strong electrophilicity of active oxygen species. The electrochemical studies for oxidation of cyclohexane mediated by EuCl3 over a glassy carbon cathode suggest that the formation of Eu2+ and O2- is important for the cyclohexane oxidation.
- Yamanaka, Ichiro,Nakagaki, Katsumi,Akimoto, Takashi,Otsuka, Kiyoshi
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- In-Situ generation of surface-active HCo(CO)y like intermediate from gold supported on ion-promoted Co3O4 for induced hydroformylation-hydrogenation of alkenes to alcohols
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In this study, a greener and stable surface-active cobalt-carbonyl like specie [HCo(CO)y] was generated via H2 and CO spillover by gold on ion-promoted cobalt oxide. The supports and catalysts syntheses were based on inverse micelle and deposition-precipitation methods, respectively. The temperature-programmed reduction was used for optimization to obtain the best supports. The catalysts with activity (Co3O4 3O4 3O4 and Au loadings 10 percent 3O4 catalyst more active than the others and displayed excellent alcohol chemoselectivity with varying regioselectivity under milder reaction conditions. The reaction was assumed to take place via the formation of [HCo(CO)y] specie, as the active catalytic site of the catalyst. The enhanced catalytic performance was also ascribed to the low-temperature reducibility and surface basicity of the nanomaterials. The stability of the catalyst was evaluated by recycling, with its mesostructure retained after four cycles.
- Akinnawo, Christianah A.,Meijboom, Reinout,Mogudi, Batsile M.,Oseghale, Charles O.
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- OXIRANE RINGS: STUDIES AND APPLICATIONS OF A NEW CHEMO AND REGIO SELECTIVE REDUCTIVE OPENING OF EPOXIDES
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The straightforward reductive opening of 1,2 epoxides to alcohols was studied and applied to several significant compounds.The reaction, which proceeds via the nucleophilic opening of the oxirane ring and the subsequent free radical dehalogenation, shows an excellent chemical yield as well as chemo and regioselectivity.This reaction was also applied to a chiral α,β-epoxyester.
- Bonini, Carlo,Fabio, Romano Di,Sotgiu, Giovanni,Cavagnero, Silvia
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- Lithium Triethylborohydride-promoted Hydroboration of Alkenes with Dialkoxyboranes
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In the presence of a catalytic ammount of lithium triethylborohydride (LiBEt3H) the hydroboration of alkenes with dialkoxyboranes is promoted markedly to provide the hydroboration products almost quantitatively under mild reaction conditions.
- Arase, Akira,Nunokawa, Yutaka,Masuda, Yuzuru,Hoshi, Masayuki
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- REGIOSELECTIVITY CHANGES IN HEXANE HYDROXYLATION BY IODOZOBENZENE CATALYZED BY TETRAARYLPORPHYRINATOIRON COMPLEXES
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Regioselectivity of hexane hydroxylation by iodozobenzene was correlated with electronic and steric constants of substituted porphyrins and revealed the increase of the relative rate of an attack at terminal methyl- and methylene-groups of hexane in sterically hindered and electron-deficient porphyrinatoiron complexes.
- Khenkin, Alexander,Koifman, Oskar,Semeikin, Alexander,Shilov, Alexander,Shteinman, Albert
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- Hydroboration. 54. New General Synthesis of Alkyldihaloboranes via Hydroboration of Alkenes with Dihaloborane-Dimethyl Sulfide Complexes. Unusual Trends in the Reactivities and Directive Effects
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The reactions of alkenes with the dimethyl sulfide complexes of the dihaloboranes (HBX2*SMe2; X = Cl, Br, I) have been studied in detail.Dichloroborane-dimethyl sulfide (HBCl2*SMe2) hydroborates representative olefins relatively slowly and requires the presence of a strong Lewis acid, such as boron trichloride, to complete the hydroboration reaction rapidly.Unexpectedly, dibromoborane-dimethyl sulfide (HBBr2*SMe2) and diiodoborane-dimethyl sulfide (HBI2*SMe2) react readily with olefins, even in the absence of such Lewis acids.This is contrary to the trend expected on the basis of the strenghts of these methyl sulfide adducts and a hydroboration mechanism involving a prior dissociation of the addition compound.The hydroboration of olefins with these reagents, followed by distillation under reduced pressure, affords alkyldihaloborane-dimethyl sulfide complexes in good yields.These are readily converted by hydrolysis into the boronic acids or by methanolysis to the corresponding esters.Oxidation with alkaline hydrogen peroxide utilizing sufficient sodium hydroxide to neutralize the hydrogen halide readily provides the corresponding alcohols.HBBr2*SMe2 and HBI2*SMe2 exhibit an unusual directive effect in the hydroboration of trisubstituted olefins, giving unexpected enhanced amounts of the Markovnikov (tertiary) derivatives.
- Brown, Herbert C.,Ravindran, N.,Kulkarni, Surendra U.
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- PHOTOCHEMICALLY-DRIVEN BIOMIMETIC OXIDATION OF ALKANES AND OLEFINES
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Photochemical oxidation of hydrocarbons using molecular oxigen as oxidant and Sn(IV)-or Sb(V)-porphyrin as photosensitizer to generate the required co-reductant is described.Fe(III)-or Mn(III)-porphyrin is the hydrocarbon-oxidation catalyst.The system is long-lived and may be used in photo-initiated spectroscopic kinetic studies.
- Shelnutt, J.A.,Trudell, D.E.
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- Alkene-pinacolborane hydroborations catalyzed by lanthanum tris[bis(trimethylsilyl)amide]
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Tris[bis(trimethylsilyl)amide] has been shown to be an effective catalyst for the hydroboration of representative alkenes and styrenes by pinacolborane.
- Horino, Yoshikazu,Livinghouse, Tom,Stan, Magdalena
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- The Milstein Bipyridyl PNN Pincer Complex of Ruthenium Becomes a Noyori-Type Catalyst under Reducing Conditions
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Hydrogenation of the dearomatized PNN ligand of the Milstein bipyridyl complex RuH(CO)[PNN] (2) gives a square-pyramidal Ru(II) product RuH(CO)[pPNN] (5). The central ring of the pPNN ligand is a piperidine. A minor byproduct of the hydrogenation reaction is complex 6 which has a dimeric structure made of two Ru(II) fragments each possessing a partly hydrogenated PNN ligand. The structures of 5 and 6 have been elucidated by NMR spectroscopy and X-ray crystallography. The PNN ligand of 2 is also hydrogenated under the conditions of the catalytic dehydrogenative coupling of ethanol to ethyl acetate. No direct evidence of the aromatized dihydride RuH2(CO)[PNN] (4) was found in this study. However, treating RuHCl(CO)[PNN] with Li[HBEt3] or reacting 2 with H2 at low temperature resulted in a structurally characterized hydride-bridged dimer (7) bearing intact aromatized bipyridyl ligands. M06-L/def2-QZVP DFT calculations provided insights into the thermodynamics of the stoichiometric reactions of this work and into the nature of the intermediates of the catalytic ester hydrogenation facilitated by RuH2(CO)[pPN(H)N] (8) formed from 5 under H2.
- Dawe, Louise N.,Karimzadeh-Younjali, Morteza,Dai, Zengjin,Khaskin, Eugene,Gusev, Dmitry G.
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- Development of a screening system for the evaluation of soybean volatiles
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Flavor properties are important factors of soybean seeds in their utilization as food materials. In order to isolate novel varieties and mutants of soybean having preferable flavor properties, a simple and efficient screening system was established using
- Matsui, Kenji,Kakumyan, Pattana,Kato, Marie,Hajika, Makita
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- Upgrading ethanol to 1-butanol with a homogeneous air-stable ruthenium catalyst
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An amide-derived N,N,N-Ru(ii) complex catalyzes the conversion of EtOH to 1-BuOH with high activity. Conversion to alcohol upgraded products exceeds 250 turnovers per hour (>50% conversion) with 0.1 mol% catalyst loading. In addition to high activity for ethanol upgrading, catalytic reactions can be set up under ambient conditions with no loss in activity.
- Tseng, Kuei-Nin T.,Lin, Steve,Kampf, Jeff W.,Szymczak, Nathaniel K.
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- Homogeneous catalytic hydrogenation of long-chain esters by an osmium pincer complex and its potential application in the direct conversion of triglycerides into fatty alcohols
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The osmium hydride complexes OsH2(CO)[NH(CH2P iPr2)2] (1) and OsHCl(CO)[NH(CH 2PiPr2)2] (2) were evaluated in the catalytic hydrogenation of hexyl octanoate and cis-3-hexenyl hexanoate to alcohols as model substrates for triglycerides. Both complexes achieve full conversion of the saturated ester at 220 °C and 800 psi pressure of hydrogen gas. In the presence of unsaturated substrates, the complexes hydrogenate CC bonds, but are subsequently ineffective in the reduction of the ester moiety. However complex 1 is capable of hydrogenating fully saturated triglycerides (i.e., hardened fats as obtained by separate initial hydrogenation of seed oils using either 1 or 2 or a standard heterogeneous hydrogenation catalyst) giving cetyl and stearyl alcohols as the main products.
- Acosta-Ramirez, Alberto,Bertoli, Marcello,Gusev, Dmitry G.,Schlaf, Marcel
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- The key role of the latent N-H group in Milstein's catalyst for ester hydrogenation
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We previously demonstrated that Milstein's seminal diethylamino-substituted PNN-pincer-ruthenium catalyst for ester hydrogenation is activated by dehydroalkylation of the pincer ligand, releasing ethane and eventually forming an NHEt-substituted derivative that we proposed is the active catalyst. In this paper, we present a computational and experimental mechanistic study supporting this hypothesis. Our DFT analysis shows that the minimum-energy pathways for hydrogen activation, ester hydrogenolysis, and aldehyde hydrogenation rely on the key involvement of the nascent N-H group. We have isolated and crystallographically characterized two catalytic intermediates, a ruthenium dihydride and a ruthenium hydridoalkoxide, the latter of which is the catalyst resting state. A detailed kinetic study shows that catalytic ester hydrogenation is first-order in ruthenium and hydrogen, shows saturation behavior in ester, and is inhibited by the product alcohol. A global fit of the kinetic data to a simplified model incorporating the hydridoalkoxide and dihydride intermediates and three kinetically relevant transition states showed excellent agreement with the results from DFT.
- Chianese, Anthony R.,He, Tianyi,Jarczyk, Cole E.,Keith, Jason M.,Kelly, Sophie. E.,Kim, Thao,Pham, John,Reynolds, Eamon F.
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- Biochemical and structural characterisation of a haloalkane dehalogenase from a marine Rhodobacteraceae
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A putative haloalkane dehalogenase has been identified in a marine Rhodobacteraceae and subsequently cloned and over-expressed in Escherichia coli. The enzyme has highest activity towards the substrates 1,6-dichlorohexane, 1-bromooctane, 1,3-dibromopropane and 1-bromohexane. The crystal structures of the enzyme in the native and product bound forms reveal a large hydrophobic active site cavity. A deeper substrate binding pocket defines the enzyme preference towards substrates with longer carbon chains. Arg136 at the bottom of the substrate pocket is positioned to bind the distal halogen group of extended di-halogenated substrates.
- Novak, Halina R.,Sayer, Christopher,Isupov, Michail N.,Gotz, Dorothee,Spragg, Andrew Mearns,Littlechild, Jennifer A.
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- Chemoselective hydrogenolysis of tetrahydrofurfuryl alcohol to 1,5-pentanediol
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Direct conversion of tetrahydrofurfuryl alcohol, which is one of the biomass-derived chemicals, to 1,5-pentanediol was realized by chemoselective hydrogenolysis catalyzed by Rh/SiO2 modified with ReOx species, and this reaction route gave higher yield than the conventional multi-step method.
- Koso, Shuichi,Furikado, Ippei,Shimao, Akira,Miyazawa, Tomohisa,Kunimori, Kimio,Tomishige, Keiichi
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- Continuous flow hydrogenation reactions by Pd catalysts onto hybrid ZrO2/PVA materials
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Palladium nanoparticles of 3.2?±?0.9?nm size were generated within 12–18 mesh pellets of hybrid zirconia/polyvinyl alcohol matrix, to afford a 0.03–0.1% Pd loading (w/w). The material was used in the catalytic, continuous flow hydrogenation reaction of multiple C[dbnd]C and C[tbnd]C bonds and nitrobenzene, showing good selectivity at full conversion and excellent resistance over prolonged time-on-stream under room temperature and 1–2?bar H2gas. No metal leaching in solution was detected as well as no additives nor regeneration steps were needed for use in hydrophilic solvents.
- Liguori, Francesca,Barbaro, Pierluigi,Sawa, Haruo
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- N-methylpyrrolidine-zinc borohydride: As a new stable and efficient reducing agent in organic synthesis
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N-Methylpyrrolidine-zinc borohydride is readily prepared and used for reduction of a variety of organic compounds such as aldehydes, ketones, acid chlorides, and esters. Reactions are performed in THF at room temperature or under reflux condition and the yields are good to excellent. Complete regio-selectivity are observed in reduction of α,β-unsaturated carbonyl compounds.
- Tajbakhsh,Lakouraj,Mohanazadeh,Ahmadi-Nejhad
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- One-pot catalytic conversion of cellulose and of woody biomass solids to liquid fuels
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Efficient methodologies for converting biomass solids to liquid fuels have the potential to reduce dependence on imported petroleum while easing the atmospheric carbon dioxide burden. Here, we report quantitative catalytic conversions of wood and cellulosic solids to liquid and gaseous products in a single stage reactor operating at 300-320 °C and 160-220 bar. Little or no char is formed during this process. The reaction medium is supercritical methanol (sc-MeOH) and the catalyst, a copper-doped porous metal oxide, is composed of earth-abundant materials. The major liquid product is a mixture of C2-C6 aliphatic alcohols and methylated derivatives thereof that are, in principle, suitable for applications as liquid fuels.
- Matson, Theodore D.,Barta, Katalin,Iretskii, Alexei V.,Ford, Peter C.
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- Selective hydrogenation of 3-Hexyn-1-ol with Pd nanoparticles synthesized via microemulsions
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In the study at hand we present a design strategy for novel catalysts which can be used for the selective hydrogenation of alkynes to alkenes. The design of the novel catalysts is based on two main ideas, namely (1) the synthesis of Pd nanoparticles via microemulsions and (2) the use of highly-ordered mesoporous silica with a 3-D pore network (FDU-12) serving as support. The nanoparticles are deposited on FDU-12 in two different ways. Firstly, we simply impregnated the support with a dispersion of the nanoparticles. The resulting catalyst was not selective at all; on the contrary, it fully hydrogenated our model alkyne, namely 3-hexyn-1-ol. Secondly, we synthesized the FDU-12 in the presence of the nanoparticles (in-situ synthesis). In this case, we obtained one catalyst which performed as well as the Lindlar catalyst although the metal content was slightly lower and our catalyst contained no Pb. Another catalyst of the same series, prepared in the presence of another stabilizer, performed as well as the NanoSelect catalyst but at a 7 times higher metal content. For the sake of comparison we also impregnated FDU-12 via classical incipient wetness impregnation and again obtained a completely nonselective catalyst. Our results demonstrate that the in-situ synthesis has great potential as regards the development of novel catalysts.
- Montsch, Thomas,Heuchel, Moritz,Traa, Yvonne,Klemm, Elias,Stubenrauch, Cosima
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- Ruthenium pincer-catalyzed acylation of alcohols using esters with liberation of hydrogen under neutral conditions
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Acylation of secondary alcohols using non-activated esters, in particular symmetrical esters (such as ethyl acetate), is achieved under neutral conditions with the liberation of molecular hydrogen. This unprecedented, environmentally benign reaction is homogenously catalyzed by a dearomatized ruthenium pincer PNN complex. Copyright
- Gnanaprakasam, Boopathy,Ben-David, Yehoshoa,Milstein, David
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- Shape Selective Alkane Hydroxylation by Metalloporphyrin Catalysts
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A series of manganese and iron porphyrins with sterically protected pockets are shown to be shape selective alkane hydroxylation catalysts.With iodosobenzene as oxidant, good regioselectivity is observed for hydroxylation of alkanes at the least hindered methyl group by using the very sterically hindered (5,10,15,20-tetrakis(2',4',6'-triphenylphenyl)porphyrinato)manganese(III) acetate (MnTTPPP(OAc)) as catalyst; The moderately hindered (5,10,15,20-tetrakis(2',4',6'-trimethoxyphenyl)porphyrinato)manganese(III) acetate shows little selectivity toward terminal CH3 hydroxylation but does show enhancement for the adjacent, ω - 1, CH2 site.Primary selectivity is dependent on the size and shape of the alkane substrate, with more bulky substituents giving greater primary selectivity.Substituting pentafluoroiodosobenzene or m-chloroperbenzoic acid as oxidants yields similar selectivity, thus conclusively demonstrating metal based oxidation via a common intermediate for these three systems.In contrast, tert-butyl hydroperoxide or 2,2,2-trifluoroethanol solubilized pentafluoroiodosobenzene show no primary carbon selectivity, and reaction product ratios are independent of the metalloporphyrin catalyst; this demonstrates that the site of oxidation with these oxidants is not metal based.The iron porphyrin derivatives also show good primary selectivity, although to a lesser degree than with the Mn derivatives, proving that these oxidations too are metal based.The regioselectivities for alkane hydroxilation shown by TTPPP derivatives are comparable to or better than those found for some isozymes of cytochrome P-450 which are responsible for primary alcohol biosynthesis from steroids, fatty acids, and alkanes.
- Cook, Bruce R.,Reinert, Thomas J.,Suslick, Kenneth S.
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Read Online
- Hydrogenation of adipic acid to 1,6-hexanediol by supported bimetallic Ir-Re catalyst
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A series of supported Ir-Re catalysts have been synthesized and used for the hydrogenation of adipic acid to 1,6-hexanediol. The influences of supporting materials and the Ir/Re atomic ratio on the catalytic performances have been studied. Results suggested that Ir-Re supported on carbon materials and alumina had appropriate acid sites and better activity for the hydrogenation of adipic acid. Compared to the monometallic catalysts, synergistic interaction was generated and electrons were delivered from Ir to Re. The uniform distribution of metal particles in the Ir-Re catalysts and the well restrained H2-spillover effect facilitated the transformation of adipic acid and the selective production of 1,6-hexanediol. The selectivity of 1,6-hexanediol was 59% with complete conversion of adipic acid at 180 °C in 10 MPa H2 after reaction for 16 h. After four times of reaction, the selectivity of 1,6-hexanediol only decreased about 4%.
- Li, Xiaoyue,Liang, Changhai,Luo, Jingjie
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Read Online
- Upgrading of Ethanol to n-Butanol via a Ruthenium Catalyst in Aqueous Solution
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The upgrading of ethanol to n-butanol via the Guerbet reaction in aqueous media has been developed. This system allows for the upgrading of ethanol to n-butanol in up to a 28% yield and 57% selectivity, at only 80 °C. This system is also able to tolerate the same feedstock ratio found in fermentation broth (water to ethanol ratio of 90:10), albeit a decrease in yield and selectivity (20% yield of n-butanol, 48% selectivity). Smaller amounts of longer-chain alcohols are also formed.
- Dibenedetto, Tarah A.,Jones, William D.
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Read Online
- Regiodivergent Reductive Opening of Epoxides by Catalytic Hydrogenation Promoted by a (Cyclopentadienone)iron Complex
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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.
- De Vries, Johannes G.,Gandini, Tommaso,Gennari, Cesare,Jiao, Haijun,Pignataro, Luca,Stadler, Bernhard M.,Tadiello, Laura,Tin, Sergey
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p. 235 - 246
(2022/01/03)
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- One-Pot Bioelectrocatalytic Conversion of Chemically Inert Hydrocarbons to Imines
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Petroleum hydrocarbons are our major energy source and an important feedstock for the chemical industry. With the exception of combustion, the deep conversion of chemically inert hydrocarbons to more valuable chemicals is of considerable interest. However, two challenges hinder this conversion. One is the regioselective activation of inert carbon-hydrogen (C-H) bonds. The other is designing a pathway to realize this complicated conversion. In response to the two challenges, a multistep bioelectrocatalytic system was developed to realize the one-pot deep conversion from heptane to N-heptylhepan-1-imine under mild conditions. First, in this enzymatic cascade, a bioelectrocatalytic C-H bond oxyfunctionalization step based on alkane hydroxylase (alkB) was applied to regioselectively convert heptane to 1-heptanol. By integrating subsequent alcohol oxidation and bioelectrocatalytic reductive amination steps based on an engineered choline oxidase (AcCO6) and a reductive aminase (NfRedAm), the generated 1-heptanol was successfully converted to N-heptylhepan-1-imine. The electrochemical architecture provided sufficient electrons to drive the bioelectrocatalytic C-H bond oxyfunctionalization and reductive amination steps with neutral red (NR) as electron mediator. The highest concentration of N-heptylhepan-1-imine achieved was 0.67 mM with a Faradaic efficiency of 45% for C-H bond oxyfunctionalization and 70% for reductive amination. Hexane, octane, and ethylbenzene were also successfully converted to the corresponding imines. Via regioselective C-H bond oxyfunctionalization, intermediate oxidation, and reductive amination, the bioelectrocatalytic hydrocarbon deep conversion system successfully realized the challenging conversion from inert hydrocarbons to imines that would have been impossible by using organic synthesis methods and provided a new methodology for the comprehensive conversion and utilization of inert hydrocarbons.
- Chen, Hui,Tang, Tianhua,Malapit, Christian A.,Lee, Yoo Seok,Prater, Matthew B.,Weliwatte, N. Samali,Minteer, Shelley D.
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supporting information
p. 4047 - 4056
(2022/02/10)
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- Hydrogenation of Esters by Manganese Catalysts
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The hydrogenation of esters catalyzed by a manganese complex of phosphine-aminopyridine ligand was developed. Using this protocol, a variety of (hetero)aromatic and aliphatic carboxylates including biomass-derived esters and lactones were hydrogenated to primary alcohols with 63–98% yields. The manganese catalyst was found to be active for the hydrogenation of methyl benzoate, providing benzyl alcohol with turnover numbers (TON) as high as 45,000. Investigation of catalyst intermediates indicated that the amido manganese complex was the active catalyst species for the reaction. (Figure presented.).
- Li, Fu,Li, Xiao-Gen,Xiao, Li-Jun,Xie, Jian-Hua,Xu, Yue,Zhou, Qi-Lin
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- Chemoenzymatic one-pot reaction from carboxylic acid to nitrile: Via oxime
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We report a new chemoenzymatic cascade starting with aldehyde synthesis by carboxylic acid reductase (CAR) followed by chemical in situ oxime formation. The final step to the nitrile is catalyzed by aldoxime dehydratase (Oxd). Full conversions of phenylacetic acid and hexanoic acid were achieved in a two-phase mode.
- Hecko, Sebastian,Horvat, Melissa,Klempier, Norbert,Martínková, Ludmila,Pátek, Miroslav,R?disch, Robert,Rudroff, Florian,Schiefer, Astrid,Weilch, Victoria,Wilding, Birgit,Winkler, Margit
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- Chromium-Catalyzed Production of Diols From Olefins
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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.
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Paragraph 0111
(2021/03/19)
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- Redox-active ligand based Mn(i)-catalyst for hydrosilylative ester reduction
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Herein a Mn(i) catalyst bearing a redox-active phenalenyl (PLY) based ligand is reported for the efficient hydrosilylation of esters to alcohols using the inexpensive silane source polymethylhydrosiloxane (PMHS) under mild conditions. Mechanistic investigations suggest a strong ligand-metal cooperation where a ligand-based single electron transfer (SET) process initiates the reaction through Si-H bond activation.
- Chakraborty, Soumi,Das, Arpan,Mandal, Swadhin K.
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supporting information
p. 12671 - 12674
(2021/12/04)
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- Reaction of Diisobutylaluminum Borohydride, a Binary Hydride, with Selected Organic Compounds Containing Representative Functional Groups
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The binary hydride, diisobutylaluminum borohydride [(iBu)2AlBH4], synthesized from diisobutylaluminum hydride (DIBAL) and borane dimethyl sulfide (BMS) has shown great potential in reducing a variety of organic functional groups. This unique binary hydride, (iBu)2AlBH4, is readily synthesized, versatile, and simple to use. Aldehydes, ketones, esters, and epoxides are reduced very fast to the corresponding alcohols in essentially quantitative yields. This binary hydride can reduce tertiary amides rapidly to the corresponding amines at 25 °C in an efficient manner. Furthermore, nitriles are converted into the corresponding amines in essentially quantitative yields. These reactions occur under ambient conditions and are completed in an hour or less. The reduction products are isolated through a simple acid-base extraction and without the use of column chromatography. Further investigation showed that (iBu)2AlBH4 has the potential to be a selective hydride donor as shown through a series of competitive reactions. Similarities and differences between (iBu)2AlBH4, DIBAL, and BMS are discussed.
- Amberchan, Gabriella,Snelling, Rachel A.,Moya, Enrique,Landi, Madison,Lutz, Kyle,Gatihi, Roxanne,Singaram, Bakthan
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supporting information
p. 6207 - 6227
(2021/05/06)
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- MOF-derived hcp-Co nanoparticles encapsulated in ultrathin graphene for carboxylic acids hydrogenation to alcohols
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Highly efficient conversion of carboxylic acids to valuable alcohols is a great challenge for easily corroded non-noble metal catalysts. Here, a series of few-layer graphene encapsulated metastable hexagonal closed-packed (hcp) Co nanoparticles were fabricated by reductive pyrolysis of metal-organic framework precursor. The sample pyrolyzed at 400 °C (hcp-Co@G400) presented outstanding performance and stability for converting a variety of functional carboxylic acids and its turnover frequency was one magnitude higher than that of conventional facc-centered cubic (fcc) Co catalysts. In situ DRIFTS spectroscopy of model reaction acetic acid hydrogenation and DFT calculation results confirm that carboxylic acid initially undergoes dehydroxylation to RCH2CO* followed by consecutive hydrogenation to RCH2CH2OH through RCH2COH*. Acetic acid prefers to vertically adsorb at hcp-Co (0 0 2) facet with a much lower adsorption energy than parallel adsorption at fcc-Co (1 1 1) surface, which plays a key role in decreasing the activation barrier of the rate-determining step of acetic acid dehydroxylation.
- Dong, Mei,Fan, Weibin,Gao, Xiaoqing,Zhu, Shanhui
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p. 201 - 211
(2021/06/03)
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- Disproportionation of aliphatic and aromatic aldehydes through Cannizzaro, Tishchenko, and Meerwein–Ponndorf–Verley reactions
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Disproportionation of aldehydes through Cannizzaro, Tishchenko, and Meerwein–Ponndorf–Verley reactions often requires the application of high temperatures, equimolar or excess quantities of strong bases, and is mostly limited to the aldehydes with no CH2 or CH3 adjacent to the carbonyl group. Herein, we developed an efficient, mild, and multifunctional catalytic system consisting AlCl3/Et3N in CH2Cl2, that can selectively convert a wide range of not only aliphatic, but also aromatic aldehydes to the corresponding alcohols, acids, and dimerized esters at room temperature, and in high yields, without formation of the side products that are generally observed. We have also shown that higher AlCl3 content favors the reaction towards Cannizzaro reaction, yet lower content favors Tishchenko reaction. Moreover, the presence of hydride donor alcohols in the reaction mixture completely directs the reaction towards the Meerwein–Ponndorf–Verley reaction. Graphic abstract: [Figure not available: see fulltext.].
- Sharifi, Sina,Sharifi, Hannah,Koza, Darrell,Aminkhani, Ali
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p. 803 - 808
(2021/07/20)
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- Primary Alcohols via Nickel Pentacarboxycyclopentadienyl Diamide Catalyzed Hydrosilylation of Terminal Epoxides
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The efficient and regioselective hydrosilylation of epoxides co-catalyzed by a pentacarboxycyclopentadienyl (PCCP) diamide nickel complex and Lewis acid is reported. This method allows for the reductive opening of terminal, monosubstituted epoxides to form unbranched, primary alcohols. A range of substrates including both terminal and nonterminal epoxides are shown to work, and a mechanistic rationale is provided. This work represents the first use of a PCCP derivative as a ligand for transition-metal catalysis.
- Lambert, Tristan H.,Steiniger, Keri A.
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supporting information
p. 8013 - 8017
(2021/10/25)
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- PROCESSES FOR PRODUCING ALCOHOLS FROM BIOMASS AND FURTHER PRODUCTS DERIVED THEREFROM
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Processes for producing alcohols from biomass are provided. The processes utilize supercritical methanol to depolymerize biomass with subsequent conversion to a mixture of alcohols. In particular the disclosure relates to continuous processes which produce high yields of alcohols through recycling gases and further employ dual reactor configurations which improve overall alcohol yields. Processes for producing higher ethers and olefins from the so-formed alcohols, through alcohol coupling and subsequent dehydration are also provided. The resulting distillate range ethers and olefins are useful as components in liquid fuels, such as diesel and jet fuel.
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Paragraph 0539-0540
(2021/11/26)
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- Improving the Catalytic Stability of Ni/TiO2 for Ethanol Guerbet Condensation: Influence of Second Metal Component
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Abstract: Ethanol Guerbet condensation (EGC) is a green process for preparing n-butanol and the development of highly effective solid catalysts is still the bottleneck of this reaction. In this work, a series of multifunctional catalysts Ni–X/TiO2 (X = Ru, Pt, Ir, Au, Cu, Mn, Co, Fe) were prepared by a co-impregnation method in order to improve the catalytic performance, especially the stability. It was found that the addition of the second metal component changed the acidity and alkalinity of Ni/TiO2 catalyst. What is more, acid site number affected ethanol conversion while alkali site number affected n-butanol selectivity. Among the Ni–X/TiO2 catalysts, Ni–Cu/TiO2 showed the best catalytic performance. The effects of preparation conditions on the catalytic performance of Ni–Cu/TiO2 were investigated and the results showed that the suitable preparation conditions were as follows: a Ni/Cu mass ratio of 59 : 1, a Ni–Cu loading of 12.5 wt %, a calcination temperature of 450°C, a calcination time of 2 h, a reduction temperature of 400°C, and a reduction time of 4?h. At a 10 wt % of catalyst loading, a reaction temperature of 210°C and a reaction time of 10 h, the ethanol conversion and the selectivity of n-butanol were 47.9 and 44.4%, respectively. Moreover, the stability of Ni–Cu/TiO2 catalyst was greatly improved due to the interaction between Ni and Cu as compared with the Ni/TiO2 catalyst: the catalytic activity of Ni–Cu/TiO2 did not decline significantly for reuse in three cycles.
- An, Hualiang,Han, Xiaoxu,Li, Shuaiqi,Wang, Yanji,Zhao, Xinqiang
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p. 632 - 640
(2021/09/28)
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- Enantiomeric synthesis of natural alkylglycerols and their antibacterial and antibiofilm activities
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Alkylglycerols (AKGs) are bioactive natural compounds that vary by alkyl chain length and degree of unsaturation, and their absolute configuration is 2S. Three AKGs (5l–5n) were synthesised in enantiomerically pure form, and were characterised for the first time together with 12 other known and naturally occurring AKGs (5a–5k, 5o). Their structures were established using 1H and 13C APT NMR with 2D-NMR, ESI-MS or HRESI-MS and optical rotation data, and they were tested for their antibacterial and antibiofilm activities. AKGs 5a–5m and 5o showed activity against five clinical isolates and P. aeruginosa ATCC 15442, with MIC values in the range of 15–125 μg/mL. In addition, at half of the MIC, most of the AKGs reduced S. aureus biofilm formation in the range of 23%–99% and P. aeruginosa ATCC 15442 biofilm formation in the range of 14%–64%. The antibiofilm activity of the AKGs assessed in this work had not previously been studied.
- Fernández Montoya, Deicy J.,Contreras Jordan, Luis A.,Moreno-Murillo, Bárbara,Silva-Gómez, Edelberto,Mayorga-Wandurraga, Humberto
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supporting information
p. 2544 - 2550
(2019/11/13)
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- Manganese Catalyzed Direct Amidation of Esters with Amines
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The transition metal catalyzed amide bond forming reaction of esters with amines has been developed as an advanced approach for overcoming the shortcomings of traditional methods. The broad scope of substrates in transition metal catalyzed amidations remains a challenge. Here, a manganese(I)-catalyzed method for the direct synthesis of amides from a various number of esters and amines is reported with unprecedented substrate scope using a low catalyst loading. A wide range of aromatic, aliphatic, and heterocyclic esters, even in fatty acid esters, reacted with a diverse range of primary aryl amines, primary alkyl amines, and secondary alkyl amines to form amides. It is noteworthy that this approach provides the first example of the transition metal catalyzed amide bond forming reaction from fatty acid esters and amines. The acid-base mechanism for the manganese(I)-catalyzed direct amidation of esters with amines was elucidated by DFT calculations.
- Fu, Zhengqiang,Wang, Xinghua,Tao, Sheng,Bu, Qingqing,Wei, Donghui,Liu, Ning
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p. 2339 - 2358
(2021/02/03)
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- BiCl3-Facilitated removal of methoxymethyl-ether/ester derivatives and DFT study of -O-C-O- bond cleavage
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A simple method for the cleavage of methoxymethyl (MOM)-ether and ester derivatives using bismuth trichloride (BiCl3) is described. The alkyl, alkenyl, alkynyl, benzyl and anthracene MOM ether derivatives, as well as MOM esters of both aliphatic and aromatic carboxylic acids, were deprotected in good yields. To better understand the molecular roles of BiCl3and water for MOM cleavage, two possible binding pathways were investigated using the density functional theory (DFT) method. The theoretical results indicate the differential initial binding site preferences of phenolic and alcoholic MOM substrates to the Bi atom and suggest that water plays a key role in facilitating the cleavage of the MOM group.
- Pacherille, Angela,Tuga, Beza,Hallooman, Dhanashree,Dos Reis, Isaac,Vermette, Mélodie,Issack, Bilkiss B.,Rhyman, Lydia,Ramasami, Ponnadurai,Sunasee, Rajesh
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supporting information
p. 7109 - 7116
(2021/05/03)
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- AVIATION BIOFUEL BASE MATERIAL, AVIATION BIOFUEL INCLUDING SAME, AND METHOD FOR MANUFACTURING AVIATION BIOFUEL
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An aviation biofuel component including 90.0 vol % or more of isoparaffins of C10 to C12 and 30.0 vol % or more of isoparaffins which are at least C10 or C12.
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- Chemo- And regioselective hydroformylation of alkenes with CO2/H2over a bifunctional catalyst
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As is well known, CO2 is an attractive renewable C1 resource and H2 is a cheap and clean reductant. Combining CO2 and H2 to prepare building blocks for high-value-added products is an attractive yet challenging topic in green chemistry. A general and selective rhodium-catalyzed hydroformylation of alkenes using CO2/H2 as a syngas surrogate is described here. With this protocol, the desired aldehydes can be obtained in up to 97% yield with 93/7 regioselectivity under mild reaction conditions (25 bar and 80 °C). The key to success is the use of a bifunctional Rh/PTA catalyst (PTA: 1,3,5-triaza-7-phosphaadamantane), which facilitates both CO2 hydrogenation and hydroformylation. Notably, monodentate PTA exhibited better activity and regioselectivity than common bidentate ligands, which might be ascribed to its built-in basic site and tris-chelated mode. Mechanistic studies indicate that the transformation proceeds through cascade steps, involving free HCOOH production through CO2 hydrogenation, fast release of CO, and rhodium-catalyzed conventional hydroformylation. Moreover, the unconventional hydroformylation pathway, in which HCOOAc acts as a direct C1 source, has also been proved to be feasible with superior regioselectivity to that of the CO pathway.
- Hua, Kaimin,Liu, Xiaofang,Wei, Baiyin,Shao, Zilong,Deng, Yuchao,Zhong, Liangshu,Wang, Hui,Sun, Yuhan
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supporting information
p. 8040 - 8046
(2021/11/01)
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- Uranyl(VI) Triflate as Catalyst for the Meerwein-Ponndorf-Verley Reaction
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Catalytic transformation of oxygenated compounds is challenging in f-element chemistry due to the high oxophilicity of the f-block metals. We report here the first Meerwein-Ponndorf-Verley (MPV) reduction of carbonyl substrates with uranium-based catalysts, in particular from a series of uranyl(VI) compounds where [UO2(OTf)2] (1) displays the greatest efficiency (OTf = trifluoromethanesulfonate). [UO2(OTf)2] reduces a series of aromatic and aliphatic aldehydes and ketones into their corresponding alcohols with moderate to excellent yields, using iPrOH as a solvent and a reductant. The reaction proceeds under mild conditions (80 °C) with an optimized catalytic charge of 2.3 mol % and KOiPr as a cocatalyst. The reduction of aldehydes (1-10 h) is faster than that of ketones (>15 h). NMR investigations clearly evidence the formation of hemiacetal intermediates with aldehydes, while they are not formed with ketones.
- Kobylarski, Marie,Monsigny, Louis,Thuéry, Pierre,Berthet, Jean-Claude,Cantat, Thibault
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supporting information
p. 16140 - 16148
(2021/11/01)
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- Hydrodeoxygenation of C4-C6 sugar alcohols to diols or mono-alcohols with the retention of the carbon chain over a silica-supported tungsten oxide-modified platinum catalyst
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The hydrodeoxygenation of erythritol, xylitol, and sorbitol was investigated over a Pt-WOx/SiO2 (4 wt% Pt, W/Pt = 0.25, molar ratio) catalyst. 1,4-Butanediol can be selectively produced with 51% yield (carbon based) by erythritol hydrodeoxygenation at 413 K, based on the selectivity over this catalyst toward the regioselective removal of the C-O bond in the -O-C-CH2OH structure. Because the catalyst is also active in the hydrodeoxygenation of other polyols to some extent but much less active in that of mono-alcohols, at higher temperature (453 K), mono-alcohols can be produced from sugar alcohols. A good total yield (59%) of pentanols can be obtained from xylitol, which is mainly converted to C2 + C3 products in the literature hydrogenolysis systems. It can be applied to the hydrodeoxygenation of other sugar alcohols to mono-alcohols with high yields as well, such as erythritol to butanols (74%) and sorbitol to hexanols (59%) with very small amounts of C-C bond cleavage products. The active site is suggested to be the Pt-WOx interfacial site, which is supported by the reaction and characterization results (TEM and XAFS). WOx/SiO2 selectively catalyzed the dehydration of xylitol to 1,4-anhydroxylitol, whereas Pt-WOx/SiO2 promoted the transformation of xylitol to pentanols with 1,3,5-pentanetriol as the main intermediate. Pre-calcination of the reused catalyst at 573 K is important to prevent coke formation and to improve the reusability.
- Betchaku, Mii,Cao, Ji,Liu, Lujie,Nakagawa, Yoshinao,Tamura, Masazumi,Tomishige, Keiichi,Yabushita, Mizuho
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supporting information
p. 5665 - 5679
(2021/08/16)
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- A Bifunctional Copper Catalyst Enables Ester Reduction with H2: Expanding the Reactivity Space of Nucleophilic Copper Hydrides
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Employing a bifunctional catalyst based on a copper(I)/NHC complex and a guanidine organocatalyst, catalytic ester reductions to alcohols with H2 as terminal reducing agent are facilitated. The approach taken here enables the simultaneous activation of esters through hydrogen bonding and formation of nucleophilic copper(I) hydrides from H2, resulting in a catalytic hydride transfer to esters. The reduction step is further facilitated by a proton shuttle mediated by the guanidinium subunit. This bifunctional approach to ester reductions for the first time shifts the reactivity of generally considered "soft"copper(I) hydrides to previously unreactive "hard"ester electrophiles and paves the way for a replacement of stoichiometric reducing agents by a catalyst and H2.
- Kaicharla, Trinadh,Ngoc, Trung Tran,Teichert, Johannes F.,Tzaras, Dimitrios-Ioannis,Zimmermann, Birte M.
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supporting information
p. 16865 - 16873
(2021/10/20)
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- Deoxygenative hydroboration of primary, secondary, and tertiary amides: Catalyst-free synthesis of various substituted amines
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Transformation of relatively less reactive functional groups under catalyst-free conditions is an interesting aspect and requires a typical protocol. Herein, we report the synthesis of various primary, secondary, and tertiary amines through hydroboration of amides using pinacolborane under catalyst-free and solvent-free conditions. The deoxygenative hydroboration of primary and secondary amides proceeded with excellent conversions. The comparatively less reactive tertiary amides were also converted to the corresponding N,N-diamines in moderate yields under catalyst-free conditions, although alcohols were obtained as a minor product.
- An, Duk Keun,Jaladi, Ashok Kumar,Kim, Hyun Tae,Yi, Jaeeun
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- Iridium-Catalyzed Domino Hydroformylation/Hydrogenation of Olefins to Alcohols: Synergy of Two Ligands
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A novel one-pot iridium-catalyzed domino hydroxymethylation of olefins, which relies on using two different ligands at the same time, is reported. DFT computation reveals different activities for the individual hydroformylation and hydrogenation steps in the presence of mono- and bidentate ligands. Whereas bidentate ligands have higher hydrogenation activity, monodentate ligands show higher hydroformylation activity. Accordingly, a catalyst system is introduced that uses dual ligands in the whole domino process. Control experiments show that the overall selectivity is kinetically controlled. Both computation and experiment explain the function of the two optimized ligands during the domino process.
- Beller, Matthias,Huang, Weiheng,Jackstell, Ralf,Jiao, Haijun,Tian, Xinxin
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supporting information
(2022/01/13)
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- Selective hydrogenation of primary amides and cyclic di-peptides under Ru-catalysis
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A ruthenium(II)-catalyzed selective hydrogenation of challenging primary amides and cyclic di-peptides to their corresponding primary alcohols and amino alcohols, respectively, is reported. The hydrogenation reaction operates under mild and eco-benign conditions and can be scaled-up.
- Subaramanian, Murugan,Sivakumar, Ganesan,Babu, Jessin K.,Balaraman, Ekambaram
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supporting information
p. 12411 - 12414
(2020/10/30)
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- Cobalt-catalysed selective synthesis of aldehydes and alcohols from esters
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Efficient and selective reduction of esters to aldehydes and alcohols is reported in which a simple cobalt pincer catalyst catalyses both transformations using diethylsilane as a reductant. Remarkably, the reaction selectivity is controlled by the stoichiometry of diethylsilane. This journal is
- Pattanaik, Sandip,Gunanathan, Chidambaram
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supporting information
p. 7345 - 7348
(2020/07/14)
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- Synthesis of Branched Biolubricant Base Oil from Oleic Acid
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The mature manufacturing of synthetic lubricants (poly-α-olefins, PAO) proceeds through oligomerization, polymerization, and hydrogenation reactions of petrochemical ethylene. In this work, we utilize the inexpensive bio-derived oleic acid as raw material to synthesize a crotch-type C45 biolubricant base oil via a full-carbon chain synthesis without carbon loss. It contains several cascade chemical processes: oxidation of oleic acid to azelaic acid (further esterification to dimethyl azelate) and nonanoic acid (both C9 chains). The latter is then selectively hydrogenated to nonanol and brominated to the bromo-Grignard reagent. In a next step, a C45 biolubricant base oil is formed by nucleophilic addition (NPA) of excessive C9 bromo-Grignard reagent with dimethyl azelate, followed by subsequent hydrodeoxygenation. The specific properties of the prepared biolubricant base oil are almost equivalent to those of the commercial lubricant PAO6 (ExxonMobil). This process provides a new promising route for the production of value-added biolubricant base oils.
- Chen, Shuang,Wu, Tingting,Zhao, Chen
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p. 5516 - 5522
(2020/09/07)
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- An Ultrasensitive Fluorescence Assay for the Detection of Halides and Enzymatic Dehalogenation
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Halide assays are important for the study of enzymatic dehalogenation, a topic of great industrial and scientific importance. Here we describe the development of a very sensitive halide assay that can detect less than a picomole of bromide ions, making it very useful for quantifying enzymatic dehalogenation products. Halides are oxidised under mild conditions using the vanadium-dependent chloroperoxidase from Curvularia inaequalis, forming hypohalous acids that are detected using aminophenyl fluorescein. The assay is up to three orders of magnitude more sensitive than currently available alternatives, with detection limits of 20 nM for bromide and 1 μM for chloride and iodide. We demonstrate that the assay can be used to determine specific activities of dehalogenases and validate this by comparison to a well-established GC-MS method. This new assay will facilitate the identification and characterisation of novel dehalogenases and may also be of interest to those studying other halide-producing enzymes.
- Aslan-üzel, A?k?n S.,Beier, Andy,Ková?, David,Cziegler, Clemens,Padhi, Santosh K.,Schuiten, Eva D.,D?rr, Mark,B?ttcher, Dominique,Hollmann, Frank,Rudroff, Florian,Mihovilovic, Marko D.,Bury?ka, Tomá?,Damborsky, Ji?í,Prokop, Zbyněk,Badenhorst, Christoffel P. S.,Bornscheuer, Uwe T.
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p. 2032 - 2039
(2020/02/11)
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- Ru0 or RuII: A Study on Stabilizing the "activated" Form of Ru-PNP Complexes with Additional Phosphine Ligands in Alcohol Dehydrogenation and Ester Hydrogenation
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The complex Ru-MACHO has been previously shown to undergo uncontrolled degradation subsequent to base-induced dehydrochlorination in the absence of a substrate. In this study, we report that stabilization of the dehydrochlorinated Ru-MACHO with phosphines furnishes complexes whose structures depend on the phosphines employed: while PMe3 led to the expected octahedral RuII complex, PPh3 provided access to a trigonal-bipyramidal Ru0 complex. Because both complexes proved to be active in base-free (de)hydrogenation reactions, thorough quantum-chemical calculations were employed to understand the reaction mechanism. The calculations show that both complexes lead to the same mechanistic scenario after phosphine dissociation and, therefore, only differ energetically in this step. According to the calculations, the typically proposed metal-ligand cooperation mechanism is not the most viable pathway. Instead, a metal-ligand-assisted pathway is preferred. Finally, experiments show that phosphine addition enhances the catalyst's performance in comparison to the PR3-free "activated" Ru-MACHO.
- Comba, Peter,Hashmi, A. Stephen K.,Menche, Maximilian,Paciello, Rocco A.,Rominger, Frank,Sch?fer, Ansgar,Schaub, Thomas,Schelwies, Mathias,Tindall, Daniel J.
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supporting information
(2020/03/30)
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- Galvanic synthesis of AgPd bimetallic catalysts from Ag clusters dispersed in a silica matrix
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While bottom-up synthetic strategies for the formation of near-monodisperse clusters have attracted much attention, top-down synthetic strategies in which metals are dispersed into clusters can also be viable. In this study, we follow up previous work that showed the formation of Ag clusters dispersed in a silica matrix by breaking up larger triangular Ag nanoparticles upon calcination in air. AgPd bimetallic catalysts were synthesized via a galvanic replacement reaction of these thermally activated Ag clusters in a silica matrix. The galvanic reaction of the Ag clusters with Pd(ii) salts was monitored by in situ XANES spectroscopy. Interestingly, extended X-ray absorption fine structure (EXAFS) spectroscopy and X-ray photoelectron spectroscopy (XPS) studies suggested that the majority of the Ag atoms are located on the surface of the resulting clusters and Pd atoms are in the core region. The catalytic activity for 3-hexyne-1-ol hydrogenation was investigated and the AgPd?SiO2 catalysts showed superior selectivity for the selective hydrogenation to 3-hexene-1-ol.
- Alyari, Maryam,Gangishetty, Mahesh,Scott, Robert W. J.,Sudheeshkumar, V.
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p. 8421 - 8428
(2020/12/30)
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- Erbium-Catalyzed Regioselective Isomerization-Cobalt-Catalyzed Transfer Hydrogenation Sequence for the Synthesis of Anti-Markovnikov Alcohols from Epoxides under Mild Conditions
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Herein, we report an efficient isomerization-transfer hydrogenation reaction sequence based on a cobalt pincer catalyst (1 mol %), which allows the synthesis of a series of anti-Markovnikov alcohols from terminal and internal epoxides under mild reaction conditions (≤55 °C, 8 h) at low catalyst loading. The reaction proceeds by Lewis acid (3 mol % Er(OTf)3)-catalyzed epoxide isomerization and subsequent cobalt-catalyzed transfer hydrogenation using ammonia borane as the hydrogen source. The general applicability of this methodology is highlighted by the synthesis of 43 alcohols from epoxides. A variety of terminal (23 examples) and 1,2-disubstituted internal epoxides (14 examples) bearing different functional groups are converted to the desired anti-Markovnikov alcohols in excellent selectivity and yields of up to 98%. For selected examples, it is shown that the reaction can be performed on a preparative scale up to 50 mmol. Notably, the isomerization step proceeds via the most stable carbocation. Thus, the regiochemistry is controlled by stereoelectronic effects. As a result, in some cases, rearrangement of the carbon framework is observed when tri-and tetra-substituted epoxides (6 examples) are converted. A variety of functional groups are tolerated under the reaction conditions even though aldehydes and ketones are also reduced to the respective alcohols under the reaction conditions. Mechanistic studies and control experiments were used to investigate the role of the Lewis acid in the reaction. Besides acting as the catalyst for the epoxide isomerization, the Lewis acid was found to facilitate the dehydrogenation of the hydrogen donor, which enhances the rate of the transfer hydrogenation step. These experiments additionally indicate the direct transfer of hydrogen from the amine borane in the reduction step.
- Liu, Xin,Longwitz, Lars,Spiegelberg, Brian,T?njes, Jan,Beweries, Torsten,Werner, Thomas
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p. 13659 - 13667
(2020/11/30)
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- Engineering Catalysts for Selective Ester Hydrogenation
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The development of efficient catalysts and processes for synthesizing functionalized (olefinic and/or chiral) primary alcohols and fluoral hemiacetals is currently needed. These are valuable building blocks for pharmaceuticals, agrochemicals, perfumes, and so forth. From an economic standpoint, bench-stable Takasago Int. Corp.'s Ru-PNP, more commonly known as Ru-MACHO, and Gusev's Ru-SNS complexes are arguably the most appealing molecular catalysts to access primary alcohols from esters and H2 (Waser, M. et al. Org. Proc. Res. Dev. 2018, 22, 862). This work introduces economically competitive Ru-SNP(O)z complexes (z = 0, 1), which combine key structural elements of both of these catalysts. In particular, the incorporation of SNP heteroatoms into the ligand skeleton was found to be crucial for the design of a more product-selective catalyst in the synthesis of fluoral hemiacetals under kinetically controlled conditions. Based on experimental observations and computational analysis, this paper further extends the current state-of-the-art understanding of the accelerative role of KO-t-C4H9 in ester hydrogenation. It attempts to explain why a maximum turnover is seen to occur starting at 25 mol % base, in contrast to only 10 mol % with ketones as substrates.
- Dub, Pavel A.,Batrice, Rami J.,Gordon, John C.,Scott, Brian L.,Minko, Yury,Schmidt, Jurgen G.,Williams, Robert F.
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p. 415 - 442
(2020/03/04)
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- Lithium Bromide/HBpin: A Mild and Effective Catalytic System for the Selective Hydroboration of Aldehydes and Ketones
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The catalytic hydroboration of aldehydes and ketones with HBpin was examined using simple and commercially available metal salts (Li, Na, and K). Among the tested salts, LiBr (0.5–1.0 mol%) was found to be an efficient catalyst for the hydroboration of various aldehydes and ketones at room temperature. Further, the chemoselective hydroboration of aldehydes over ketones was also demonstrated.
- An, Duk Keun,Choi, Hyeon Seong,Hwang, Hyonseok,Kim, Hanbi,Lee, Ji Hye,Shin, Hye Lim,Yi, Jaeeun
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p. 1009 - 1018
(2020/10/12)
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- Novel nickel nanoparticles stabilized by imidazolium-amidinate ligands for selective hydrogenation of alkynes
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The main challenge in the hydrogenation of alkynes into (E)- or (Z)-alkenes is to control the selective formation of the alkene, avoiding the over-reduction to the corresponding alkane. In addition, the preparation of recoverable and reusable catalysts is of high interest. In this work, we report novel nickel nanoparticles (Ni NPs) stabilized by three different imidazolium-amidinate ligands (ICy·(Ar)NCN; L1: Ar = p-tol, L2: Ar = p-anisyl and L3: Ar = p-ClC6H4). The as-prepared Ni NPs were fully characterized by (HR)-TEM, XRD, WASX, XPS and VSM. The nanocatalysts are active in the hydrogenation of various substrates. They present a remarkable selectivity in the hydrogenation of alkynes towards (Z)-alkenes, particularly in the hydrogenation of 3-hexyne into (Z)-3-hexene under mild reaction conditions (room temperature, 3% mol Ni and 1 bar H2). The catalytic behaviour of Ni NPs was influenced by the electron donor/acceptor groups (-Me, -OMe, -Cl) in the N-aryl substituents of the amidinate moiety of the ligands. Due to the magnetic character of the Ni NPs, recycling experiments were successfully performed after decantation in the presence of an external magnet, which allowed us to recover and reuse these catalysts at least 3 times preserving both activity and chemoselectivity.
- López-Vinasco, Angela M.,Martínez-Prieto, Luis M.,Asensio, Juan M.,Lecante, Pierre,Chaudret, Bruno,Cámpora, Juan,Van Leeuwen, Piet W. N. M.
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p. 342 - 350
(2020/02/04)
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- The construction of novel and efficient hafnium catalysts using naturally existing tannic acid for Meerwein-Ponndorf-Verley reduction
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The conversion of carbonyl compounds into alcohols or their derivatives via the catalytic transfer hydrogenation (CTH) process known as Meerwein-Ponndorf-Verley reduction is an important reaction in the reaction chain involved in biomass transformation. The rational design of efficient catalysts using natural and renewable materials is critical for decreasing the catalyst cost and for the sustainable supply of raw materials during catalyst preparation. In this study, a novel hafnium-based catalyst was constructed using naturally existing tannic acid as the ligand. The prepared hafnium-tannic acid (Hf-TA) catalyst was characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and thermogravimetry (TG). Hf-TA was applied in the conversion of furfuraldehyde (FD) to furfuryl alcohol (FA) using isopropanol (2-PrOH) as both the reaction solvent and the hydrogen source. Both preparation conditions and the effects of the reaction parameters on the performance of the catalyst were studied. Under the relatively mild reaction conditions of 70 °C and 3 h, FD (1 mmol) could be converted into FA with a high yield of 99.0%. In addition, the Hf-TA catalyst could be reused at least ten times without a notable decrease in activity and selectivity, indicating its excellent stability. It was proved that Hf-TA could also catalyze the conversion of various carbonyl compounds with different structures. The high efficiency, natural occurrence of tannic acid, and facile preparation process make Hf-TA a potential catalyst for applications in the biomass conversion field.
- Deng, Lijuan,Hao, Jianxiu,He, Runxia,Li, Na,Liu, Quansheng,Wang, Xiaolu,Zhao, Hongye,Zhi, Keduan,Zhou, Huacong
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p. 6944 - 6952
(2020/03/03)
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- Multistep Engineering of Synergistic Catalysts in a Metal-Organic Framework for Tandem C-O Bond Cleavage
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Cleavage of strong C-O bonds without breaking C-C/C-H bonds is a key step for catalytic conversion of renewable biomass to hydrocarbon feedstocks. Herein we report multistep sequential engineering of orthogonal Lewis acid and palladium nanoparticle (NP) catalysts in a metal-organic framework (MOF) built from (Al-OH)n secondary building units and a mixture of 2,2′-bipyridine-5,5′-dicarboxylate (dcbpy) and 1,4-benzenediacrylate (pdac) ligands (1) for tandem C-O bond cleavage. Ozonolysis of 1 selectively removed pdac ligands to generate Al2(OH)(OH2) sites, which were subsequently triflated with trimethylsilyl triflate to afford strongly Lewis acidic sites for dehydroalkoxylation. Coordination of Pd(MeCN)2Cl2 to dcbpy ligands followed by in situ reduction produced orthogonal Pd NP sites in 1-OTf-PdNP as the hydrogenation catalyst. The selective and precise transformation of 1 into 1-OTf-PdNP was characterized step by step using powder X-ray diffraction, transmission electron microscopy, thermogravimetric analysis, inductively coupled plasma mass spectrometry, infrared spectroscopy, and X-ray absorption spectroscopy. The hierarchical incorporation of orthogonal Lewis acid and Pd NP active sites endowed 1-OTf-PdNP with outstanding catalytic performance in apparent hydrogenolysis of etheric, alcoholic, and esteric C-O bonds to generate saturated alkanes via a tandem dehydroalkoxylation-hydrogenation process under relatively mild conditions. The reactivity of C-O bonds followed the trend of tertiary carbon > secondary carbon > primary carbon. Control experiments demonstrated the heterogeneous nature and recyclability of 1-OTf-PdNP and its superior catalytic activity over the homogeneous counterparts. Sequential engineering of multiple catalytic sites in MOFs thus presents a unique opportunity to address outstanding challenges in sustainable catalysis.
- Brzezinski, Carter,Chen, Justin S.,Feng, Xuanyu,Lin, Wenbin,Song, Yang,Xu, Ziwan
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supporting information
p. 4872 - 4882
(2020/04/01)
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- Ruthenium-catalyzed hydrogenation of CO2as a route to methyl esters for use as biofuels or fine chemicals
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A novel robust diphosphine-ruthenium(ii) complex has been developed that can efficiently catalyze both the hydrogenation of CO2 to methanol and its in situ condensation with carboxylic acids to form methyl esters; a TON of up to 3260 is achievable for the CO2 to methanol step. Both aromatic and aliphatic carboxylic acids can be transformed to their corresponding methyl esters with high conversion and selectivity (17 aliphatic and 18 aromatic examples). On the basis of a series of experiments, a mechanism has been proposed to account for the various steps involved in the catalytic pathway. More importantly, this approach provides a promising route for using CO2 as a C1 source for the production of biofuels, fine chemicals and methanol.
- Li, Yong,Liu, Qingbin,Ma, Yanping,Solan, Gregory A.,Sun, Wen-Hua,Wang, Zheng,Zhang, Qiuyue,Zhao, Ziwei,Zhong, Yanxia
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p. 6766 - 6774
(2020/08/25)
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- METHOD FOR PRODUCING ALCOHOL
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PROBLEM TO BE SOLVED: To provide a method for producing selectively alcohol from carboxylic acid under mild conditions. SOLUTION: In the presence of a catalyst with M1 and M2 as metal species supported on a support, a substrate is reduced to produce a corresponding alcohol. (M1 is Rh, Pt, Ru, Ir, or Pd; M2 is Sn, V, Mo, W, or Re; the support is ZrO2, hydroxyapatite, Nb2O5, fluoroapatite, or hydrotalcite; the substrate is the formula 1a, 1b, or 1c). SELECTED DRAWING: None COPYRIGHT: (C)2020,JPO&INPIT
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Paragraph 0101-0110
(2020/11/26)
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- METHOD FOR PRODUCING 1-OCTANOL
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The present invention relates to a method for producing 1-octanol comprising a contact step between ethanol, n-hexanol and two catalysts A and B, wherein catalyst A comprises a metal oxide comprising Ga and a noble metal and catalyst B comprises a metal oxide comprising Cu, Ni or any mixture thereof.
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Paragraph 0165
(2019/10/23)
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- A POCO type pincer complex of iridium: Synthesis, characterization, and catalysis
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A convenient synthesis of a new POCO-type pincer ligand, “tBuPOCOH” (3-(di-tert-butylphosphinito)acetophenone is reported. Metallation using [Ir(COD)Cl]2 provides the dimeric species (μ-Cl-[tBuPOCOIrHCl]2) (1a) as a major product, along with isomer 1b. Though not fully characterized, 1b is shown to be chemically equivalent to 1a by a series of experiments with AgOTf and CO which lead to formation of a single product, tBuPOCOIr(CO)HOTf (3). The 1a/b mixture gives inferior results to iPrPCPIr when used as pre-catalyst in the dehydrogenative coupling of vinyl arenes, though olefin isomerization activity is enhanced. This system was also evaluated in the Geurbet conversion of ethanol to n-butanol and higher alcohols. The CO adducts of 1a/b, cis/trans-2, were found to give the best results as pre-catalyst, achieving a 33% yield of n-butanol and an overall 47% yield of n-alcohols with a catalyst loading of 0.5% when heated at 150 °C for 4 hours. This represents the first example of a pincer ligated iridium complex as catalyst in the Geurbet reaction of ethanol.
- Wilklow-Marnell, Miles,Brennessel, William W.
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- Successive vapour phase Guerbet condensation of ethanol and 1-butanol over Mg-Al oxide catalysts in a flow reactor
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The successive vapour phase condensation of ethanol and 1-butanol (via Guerbet reaction) in a flow reactor under atmospheric pressure was studied over catalytic Mg-Al oxide compositions. Wherein the vapour phase condensation of 1-butanol to 2-ethyl-1-hexanol in flow has been investigated for the first time. The acid/base capacity ratio, which is determined by the Mg/Al ratio, is an important characteristic for the activity and selectivity of Mg-Al oxide catalysts in the abovementioned processes. The carbon chain length of the reacting alcohols, an arrangement of surface active sites and other steric factors also have an impact on Guerbet condensation in the vapour phase. High productivity of Mg-Al oxide system to the Guerbet alcohols: 1-butanol – 25 g/(Lcat·h), 2-ethyl-1-hexanol – 19 g/(Lcat·h), has been achieved. The results have shown a prospect of successive conversion realization: 1) ethanol → 1-butanol; 2) 1-butanol → 2-ethyl-1-hexanol for the production of 2-ethyl-1-hexanol from ethanol.
- Larina, Olga V.,Valihura, Karina V.,Kyriienko, Pavlo I.,Vlasenko, Nina V.,Balakin, Dmytro Yu.,Khalakhan, Ivan,?endak, Toma?,Soloviev, Sergiy O.,Orlyk, Svitlana M.
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- Diaminodiphosphine tetradentate ligand and ruthenium complex thereof, and preparation methods and applications of ligand and complex
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The invention discloses a diaminodiphosphine tetradentate ligand and a ruthenium complex thereof, and preparation methods and applications of the ligand and the complex, and provides a ruthenium complex represented by a formula I, wherein L is a diaminodiphosphine tetradentate ligand represented by a formula II, and X and Y are respectively and independently chlorine ion, bromine ion, iodine ion,hydrogen negative ion or BH4. According to the present invention, the ruthenium complex exhibits excellent catalytic activity in the catalytic hydrogenation reactions of ester compounds, has high yield and high chemical selectivity, is compatible with conjugated and non-conjugated carbon-carbon double bond, carbon-carbon triple bond, epoxy, halogen, carbonyl and other functional groups, and hasgreat application prospects.
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Paragraph 0301-0303; 0305
(2019/11/04)
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- Lithium tert-Butoxide-catalyzed Hydroboration of Carbonyl Compounds
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We report the successful hydroboration of aldehydes and ketones with pinacolborane using 1 mol % lithium tert-butoxide under ambient conditions. The present protocol was applicable to various aldehydes and ketones, and the corresponding boronate esters and subsequent alcohols were obtained in good to excellent yields. In addition, this high-yielding practical method could be extended to the reduction of ester groups. Under optimized conditions, LiOtBu facilitate the hydroboration of ester groups quantitatively.
- Kim, Jea Ho,Jaladi, Ashok Kumar,Kim, Hyun Tae,An, Duk Keun
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p. 971 - 975
(2019/08/30)
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- Preparation of a Series of Supported Nonsymmetrical PNP-Pincer Ligands and the Application in Ester Hydrogenation
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In contrast to their symmetrical analogues, nonsymmetrical PNP-type ligand motifs have been less investigated despite the modular pincer structure. However, the introduction of mixed phosphorus donor moieties provides access to a larger variety of PNP ligands. Herein, a facile solid-phase synthesis approach towards a diverse PNP-pincer ligand library of 14 members is reported. Contrary to often challenging workup procedures in solution-phase, only simple workup steps are required. The corresponding supported ruthenium-PNP catalysts are screened in ester hydrogenation. Usually, industrially applied heterogeneous catalysts require harsh conditions in this reaction (250–350 °C at 100–200 bar) often leading to reduced selectivities. Heterogenized reusable Ru-PNP catalysts are capable of reducing esters and lactones selectively under mild conditions.
- Konrath, Robert,Spannenberg, Anke,Kamer, Paul C. J.
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supporting information
p. 15341 - 15350
(2019/11/14)
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