- Intracrystalline reactivity of layered double hydroxides: Carboxylate alkylations in dry media
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This work concerns the reactivity in dry media conditions, i.e. without solvents, of layered double hydroxide (LDH) solids, containing carboxylate ions in their structure, towards alkyl and benzyl halides. Reaction occurs giving the corresponding esters, with excellent yield and selectivity, and preserving the lamellar arrangement of the pristine solids. The reactions were activated by conventional thermal treatment (100 °C) or by microwave (MW) irradiation.
- Garcia-Ponce, Angel Luis,Prevot, Vanessa,Casal, Blanca,Ruiz-Hitzky, Eduardo
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- Nitrous Oxide as a Nucleophile in the Formation of a New Reactive Intermediate from Benzyl Cations in the Solvolysis of Benzyl Azoxytosylate
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Rate and product analytical results of solvolysis of benzyl azoxytosylate in 1:1 (v/v) trifluoroethanol : water require two product-forming routes: one involves a long-lived intermediate (formed from benzyl cations and nitrous oxide) which is trappable by
- Maskill, H.,Jencks, William P.
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- Reactivity of silole within a core-modified porphyrin environment: Synthesis of 21-silaphlorin and its conversion to carbacorrole
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Condensation of 1,1-dimethyl-3,4-diphenyl-2,5-bis(p-tolylhydroxymethyl) silole with pyrrole and p-tolylaldehyde did not form the expected 21,21-dimethyl-2,3-diphenyl-5,10,15,20-tetra(p-tolyl)-21 -silaporphy rin, but rather its reduced derivative, 21-silap
- Skonieczny, Janusz,Latos-Grazynski, Lechoslaw,Szterenberg, Ludmila
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- REDUCTIVE COUPLING OF AROMATIC ALDEHYDES BY OCTACARBONYL DIFERRATE
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The reaction of aromatic aldehydes with Fe(CO)5 or Fe3(CO)12 in pyridine gives the corresponding 1,2-diaryl-1,2-ethanediols as major products in good yields.A reactive species of this reaction is octacarbonyl diferrate (2-).
- Ito, Keiji,Nakanishi, Saburo,Otsuji, Yoshio
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- Novel preparation of 2,1-benzothiazine derivatives from sulfonamides with [hydroxy(tosyloxy)iodo]arenes
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Cyclization of sulfonamides bearing an aromatic ring at the β-position with various organohypervalent iodine compounds was carried out to form the corresponding 2,1-benzothiazine derivatives. Among them, the cyclization effectively proceeded with [hydroxy
- Misu, Yuhta,Togo, Hideo
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- Manganese Catalyzed Hydrogenation of Organic Carbonates to Methanol and Alcohols
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The first example of a homogeneous catalyst based on an earth-abundant metal for the hydrogenation of organic carbonates to methanol and alcohols is reported. Based on the mechanistic investigation, which indicates metal-ligand cooperation between the manganese center and the N?H group of the pincer ligand, we propose that the hydrogenation of organic carbonates to methanol occurs via formate and aldehyde intermediates. The reaction offers an indirect route for the conversion of CO2 to methanol, which coupled with the use of an earth abundant catalyst, makes the overall process environmentally benign and sustainable.
- Kumar, Amit,Janes, Trevor,Espinosa-Jalapa, Noel Angel,Milstein, David
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- Oxidation of toluene in NOx free air: product distribution and mechanism
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Product distributuion resulting from the oxidation in air initiated by chlorine atoms, by toluene photolysis, and by hydroxyl radicals were studied at atmospheric pressure in the absence of nitrogen oxides.In the first case only benzaldehyde and benzylalcohol with a ratio of 7.8 +/- 1.7 were observed, from wich a branching ratio α = 0.76 +/- 0.05 was derived for the radical propagating pathway of the self-reaction of benzylperoxy radicals.In the second and third case the apparent branching ratio decreased to α = 0.56 +/- 0.07 and 0.37 +/- 0.08, respectively, indicating the occurence of additional reactions between benzylperoxy and other peroxy radicals.The major ring retaining products resulting from the reaction of OH with toluene were o-cresol, p-cresol, and methyl-p-benzo-quinone (57.9 +/- 12.5percent reacted carbon, corrected for secondary losses), in addition to 7.7 +/- 1.6percent benzaldehyde and benzylalcohol arising from methyl hydrogen abstraction.Formaldehyde, acetaldehyde, glyoxal, methylglyoxal, carbon monoxide, and carbon dioxide were observed as ring cleavage products (25.0 +/- 7.2percent).Except for CO2, which appears to be an important ring cleavage product only under NOx-free conditions, the distribution of ring cleavage products was similar to that found by Gery et al. (1985) in the presence of NOx.Comparison of experimental data and results from computer simulations show that self-reactions of the hydroxy-methyl-cyclo-hexadienylperoxy radicals are negligible compared to internal rearrangement reactions leading to ring stabilization or ring cleavage.The mechanisms of CO2 production appears to require the formation of a Criegee intermediate.
- Seuwen, P.,Warneck, P.
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- Iron-catalyzed hydrosilylation of esters
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The first hydrosilylation of esters catalyzed by a well defined iron complex has been developed. Esters are converted to the corresponding alcohols at 100 °C, under solvent-free conditions and visible light activation. Copyright
- Bezier, David,Venkanna, Gopaladasu T.,Castro, Luis C. Misal,Zheng, Jianxia,Roisnel, Thierry,Sortais, Jean-Baptiste,Darcel, Christophe
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- Solvent-free reduction of carboxylic acids to alcohols with NaBH4 promoted by 2,4,6-trichloro-1,3,5-triazine and PPh3 in the presence of K2CO3
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A simple, rapid, and eco-friendly method for NaBH4 reduction of carboxylic acids to alcohols under solvent-free conditions was developed using a combination of 2,4,6-trichloro-1,3,5-triazine (TCT) with a catalytic amount of triphenylphosphine as an acid activator. With the 1 : 0.2 : 1.5 : 2 mole ratio of TCT : PPh3 : K2CO3 : NaBH4, carboxylic acids including aromatic acids, aliphatic acids, and N-protected α-amino acids (Fmoc, Z) could readily undergo reduction to give the corresponding alcohols in good to excellent yields within 10 min.
- Jaita, Subin,Kaewkum, Pantitra,Duangkamol, Chuthamat,Phakhodee, Wong,Pattarawarapan, Mookda
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- A Pd@Zeolite Catalyst for Nitroarene Hydrogenation with High Product Selectivity by Sterically Controlled Adsorption in the Zeolite Micropores
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The adsorption of molecules on metal nanoparticles can be sterically controlled through the use of zeolite crystals, which enhances the product selectivity in hydrogenations of reactants with more than one reducible group. Key to this success was the fixation of Pd nanoparticles inside Beta zeolite crystals to form a defined structure (Pd@Beta). In the hydrogenation of substituted nitroarenes with multiple reducible groups as a model reaction, the Pd@Beta catalyst exhibited superior selectivity for hydrogenation of the nitro group, outperforming both conventional Pd nanoparticles supported on zeolite crystals and a commercial Pd/C catalyst. The extraordinary selectivity of Pd@Beta was attributed to the sterically selective adsorption of the nitroarenes on the Pd nanoparticles controlled by the zeolite micropores, as elucidated by competitive adsorption and adsorbate displacement tests. Importantly, this strategy is general and was extended to the synthesis of selective Pt and Ru catalysts by fixation inside Beta and mordenite zeolites.
- Zhang, Jian,Wang, Liang,Shao, Yi,Wang, Yanqin,Gates, Bruce C.,Xiao, Feng-Shou
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- Synthesis of β-hydroxy-α,α-disubstituted amino acids through the orthoamide-type overman rearrangement of an α,β-unsaturated ester and stereodivergent intramolecular SN2′ reaction: Development and application to the total synthesis of sphingofungin F
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The development of a two-step synthesis for β-hydroxy-α,α- disubstituted amino acid derivatives from cyclic orthoamide is reported. The first step is the orthoamide-type Overman rearrangement of an α,β-unsaturated ester to give a sterically hindered α,α-disubstituted amidoester. The α,β-unsaturated ester is known to be a challenging substrate in the conventional Overman rearrangement due to the competitive aza-Michael reaction. However, suppression of the aza-Michael reaction is realized by two factors; 1) the high reaction temperature, and 2) an alkyl substituent at the α-position. The second step is stereodivergent intramolecular SN2′ reaction for the installation of a hydroxy group at the β-position. Either syn- or anti-type SN2′ reaction is possible by simply changing the reaction conditions. The developed method can provide all four possible stereoisomers of the β-hydroxy-α,α-disubstituted amino acid, and is successfully applied to the total synthesis of sphingofungin F.
- Sugai, Tomoya,Usui, Shunme,Tsuzaki, Shun,Oishi, Hiroki,Yasushima, Daichi,Hisada, Shoko,Fukuyasu, Takahiro,Oishi, Takeshi,Sato, Takaaki,Chida, Noritaka
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- Pt/ZrO2: An efficient catalyst for aerobic oxidation of toluene in aqueous solution
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The heterogeneous oxidation of toluene in aqueous medium has been investigated. Artificially contaminated water with aromatic compound (toluene) was exposed to a simple platinized zirconia (1% Pt/ZrO2) catalyst in the presence of molecular oxyg
- Mohammad, Sadiq,Mohammad, Ilyas
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- Organometallic chemistry sans organometallic reagents: Modulated electron-transfer reactions of sub valent early transition metal salts
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The potential of low-valent, early transition-metal reagents as selective reductants in organic chemistry has been foreshadowed by intensive research on the ill-defined and heterogeneous subvalent titanium intermediates generated in the McMurry reaction and its numerous variants. As part of a long-term research effort to develop soluble, well-defined transition-metal reductants of modulated and selective activity toward organic substrates, the THF-soluble reductant, titanium dichloride, has been thoroughly examined, as well as the analogous ZrCl2 and HfCl2 reagents, all of which are readily obtainable by the alkylative reduction of the Group 4 tetrachloride by butyllithium in THF. Noteworthy is that such interactions of MCl4, with butyllithium in hydrocarbon media lead, in contrast, to M(III) or M(IV) halide hydrides. Analogous alkylative reductions in THF applied to VCl4, CrCl3, and MoCl5 have yielded reducing agents similar to those obtained from MCl4 but gradated in their reactivity. Such reductants have proved capable of coupling carbonyl derivatives, benzylic halides, acetylenes and certain olefins in a manner consistent with an oxidative addition involving a two-electron transfer (TET). Such a reaction pathway is consistent with the observed stereochemistry for pinacol formation from ketones and for the reductive dimerization of alkynes. In contrast to the reaction of CrCl3 with two equivalents of butyllithium, which leads to a CrCl intermediate, the interaction of CrCl3 in THF with four equivalents of butyllithium at -78°C yields a reagent of the empirical formulation, LiCrH4 · 2 LiCl · 2 THF, as supported by elemental and gasometric analysis of its protolysis. This hydridic reductant cleaves a wide gamut of o carbon-heteroatom bonds (C-X, C-O, C-S and C-N), towards which the CrCl reductant is unreactive. The type of cleavage and/or coupled products resulting from the action of "LiCrH4" on these substrates is best understood as arising from single-electron transfer (SET). In light of the aforementioned findings, the gradated reducing action noted among TiCl2, ZrCl2, HfCl2 and CrCl, as well as the contrasting reducing behavior between CrCl and LiCrH4, there is no doubt that future research with early transition metals will continue to yield novel reductants of modulated and site-selective reactivity. VCH Verlagsgesellschaft mbH,.
- Eisch, John J.,Shi, Xian,Alila, Joseph R.,Thiele, Sven
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- Tailor-Made Ruthenium-Triphos Catalysts for the Selective Homogeneous Hydrogenation of Lactams
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The development of a tailored tridentate ligand enabled the synthesis of a molecular ruthenium-triphos catalyst, eliminating dimerization as the major deactivation pathway. The novel catalyst design showed strongly increased performance and facilitated the hydrogenation of highly challenging lactam substrates with unprecedented activity and selectivity. Bulky catalysts: A tailored sterically demanding tridentate ligand enabled the synthesis of a novel molecular ruthenium-triphos catalyst, which eliminates dimerization as the major deactivation pathway. The novel catalyst design showed increased performance and facilitated the hydrogenation of highly challenging lactam substrates with unprecedented activity and selectivity.
- Meuresch, Markus,Westhues, Stefan,Leitner, Walter,Klankermayer, Jürgen
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- Highly efficient tetradentate ruthenium catalyst for ester reduction: Especially for hydrogenation of fatty acid esters
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A new tetradentate ruthenium complex has been developed for hydrogenation of esters. The catalysts structure features a pyridinemethanamino group and three tight chelating five-membered rings. The structure character is believed to be responsible for its high stability and high carbonylation-resistant properties. Thus, this catalyst shows outstanding performance in the catalytic hydrogenation of a variety of esters, especially for fatty acid esters, which may be used in practical applications. New insight on designing hydrogenation catalyst for reducing esters to alcohols has been provided through theoretical calculations.
- Tan, Xuefeng,Wang, Yan,Liu, Yuanhua,Wang, Fangyuan,Shi, Liyang,Lee, Ka-Ho,Lin, Zhenyang,Lv, Hui,Zhang, Xumu
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- Cobalt-Catalyzed Reductive Alkylation of Amines with Carboxylic Acids
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Direct reductive alkylation of amines with carboxylic acid is carried out by using an inexpensive, air-stable cobalt/triphos catalytic system with molecular hydrogen as the reductant. This efficient synthetic method proceeds through reduction and condensation, followed by reduction of the in situ-generated imine into the amine in a green catalytic process.
- Emayavaramban, Balakumar,Chakraborty, Priyanka,Sundararaju, Basker
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- Copper(ii) induced oxidative modification and complexation of a schiff base ligand: Synthesis, crystal structure, catalytic oxidation of aromatic hydrocarbons and DFT calculation
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A mononuclear square planar complex [CuII(Lf)] (1) was synthesized and structurally characterized by single crystal X-ray diffraction studies. Though we have started with the Schiff base H 2La with two -CH2
- Biswas, Surajit,Dutta, Arpan,Dolai, Malay,Debnath, Mainak,Jana, Atish Dipankar,Ali, Mahammad
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- THE GAS-PHASE REDUCTIVE DIMERIZATION OF BENZALDEHYDE ON A FUSED IRON CATALYST
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The gas-phase heterogeneous catalytic reductive dimerization of benzaldehyde to trans-stilbene and dibenzyl was carried out on a reduced promoted fused iron catalyst.The mechanism of this reaction was examined.
- Glebov, L. S.,Shuikin, A. N.,Kliger, G. A.,Mikaya, A. I.,Zaikin, V. G.,et al.
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- Palladium-catalyzed hydrodehalogenation of aryl halides using paraformaldehyde as the hydride source: High-throughput screening by paper-based colorimetric iodide sensor
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Paraformaldehyde was employed as a hydride source in the palladium-catalyzed hydrodehalogenation of aryl iodides and bromides. High throughput screening using a paper-based colorimetric iodide sensor (PBCIS) showed that Pd(OAc)2 and Cs2CO3 were the best catalyst and base, respectively. Aryl iodides and bromides were hydrodehalogenated to produce the reduced arenes using Pd(OAc)2 and Pd(PPh3)4 catalyst. This catalytic system showed good functional group tolerance. In addition, it was found that paraformaldehyde is the hydride source and the reducing agent for the formation of palladium nanoparticles.
- Pyo, Ayoung,Kim, Sudeok,Kumar, Manian Rajesh,Byeun, Aleum,Eom, Min Sik,Han, Min Su,Lee, Sunwoo
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- Variations on an NHC theme: Which features enhance catalytic transfer hydrogenation with ruthenium complexes?
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N-heterocyclic carbene (NHC) based ruthenium complexes were studied as catalysts for the transfer hydrogenation of ketones. Variations in the catalyst structure were investigated for their impact on hydrogenation and catalyst stability. Catalyst attributes included bis- or mono-NHC ligands, pendant ether groups in some cases, and arene ligands of varied bulk and donor strength. Ruthenium complexes were synthesized and fully characterized, including complexes with a monodentate NHC ligand containing a tethered ether N substituent (ImEt,CH2CH2OEtRuCl2(η6-arene); arene = benzene (4), p-cymene (5), hexamethylbenzene (6)), a complex with a monodentate NHC ligand with solely alkyl N substituents (Im Et,PentylRuCl2(η6-p-cymene) (8)), and a complex with a bis-NHC ligand ([RuCl(methylenebis(ImEt) 2)(η6-p-cymene)]PF6 (7)) (Im = imidazole-derived NHC; superscripts indicate N substituents). X-ray crystal structures were obtained for 4, 5, 7, and 8. All of the ruthenium complexes were tested and found to be active transfer hydrogenation catalysts for the reduction of acetophenone to 1-phenylethanol in basic 2-propanol. Precatalyst 4, which contains a tethered ether group and benzene ligand, was found to be the most active catalyst. Variable-temperature 1H NMR studies of complexes 4-6 show that arene lability increases in the order C 6Me6 -1 and 845, respectively, for ketone reduction with catalyst 4.
- Depasquale, Joseph,Kumar, Mukesh,Zeller, Matthias,Papish, Elizabeth T.
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- A New Approach for Oxygenation Using Nitric Oxide under the Influence of N-Hydroxyphthalimide
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An approach for partial oxygenation through a carbocation as an intermediate was successfully developed by using nitric oxide under the influence of N-hydroxyphthalimide. Thus, a variety of benzylic ethers were converted into the corresponding partially oxidized compounds, which are difficult to prepare by conventional methods, in high yields. For example, the reaction of phthalane with NO in the presence of a catalytic amount of NHPI at 60°C gave phthalaldehyde in 80% yield. The reaction was found to proceed through the formation of a hemiacetal, such as 1-hydroxyphthalane. In addition, 1,3-di-tert-butoxymethyl benzene afforded 1,3-benzenedicarbaldehyde in good yield. On the other hand, isochroman was converted into 1,1′-oxodiisochromane under these reaction conditions. The reaction of ethers with NO in the presence of a NHPI catalyst is thought to proceed via the formation of a carbocation as an intermediate. A possible reaction path was suggested.
- Eikawa, Masahiro,Sakaguchi, Satoshi,Ishii, Yasutaka
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- HOMOGENEOUS HYDROGENATION OF KETONES USING CHROMIUM HEXACARBONYL AS CATALYST PRECURSOR IN THE PRESENCE OF BASES
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The hydrogenation of ketones at 100-120 degC and 100 bar H2 is catalyzed by Cr(CO)6 in methanol solution in the presence of NaOMe.The reaction is inhibited by CO and the rate increases with increasing H2 pressure and base: chromium ratio.In a stoichiometric reaction at 75 degC, HCr(CO)5- hydrogenates ketones to alcohols, while forming Cr2(CO)102-.A catalytic cycle involving alkoxychromium complexes, R2CHOCr(CO)5-, as intermediates is proposed.Similar hydrogenation catalysts are obtained from W(CO)6 and Mo(CO)6; the latter is the most active and may be used even at 70-80 degC.
- Marko, Laszlo,Nagy-Magos, Zsuzsa
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- One-pot double benzylation of 2-substituted pyridines using palladium-catalyzed decarboxylative coupling of sp2 and sp3 carbons
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An efficient and practical decarboxylative double benzylation method for various 2-picolinic acids has been established by using a bimetallic catalytic system of palladium(II) chloride (PdCl2) and silver(I) oxide (Ag2O), which offered a variety of diarylmethane derivatives with moderate to good yields.
- Wang, Yaping,Li, Xinjian,Leng, Faqiang,Zhu, Helong,Li, Jingya,Zou, Dapeng,Wu, Yangjie,Wu, Yusheng
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- A highly active worm-like PtMo nanowire for the selective synthesis of dibenzylamines
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Worm-like nanowires are among the most active nanomaterials. In this study, we report the synthesis of dibenzylamine (DBA) motifs from reductive amination of either aldehydes or nitriles catalyzed by entirely new worm-like PtMo nanowires (PtMo WNWs). Under the assistance of H2 gas, PtMo WNWs can be prepared in a facile manner, following which, their structure and composition are characterized by TEM, XRD, XPS, etc. Upon careful optimization of reaction parameters, the as-prepared PtMo WNWs work effectively in the activation of dihydrogen molecules, and both aldehydes and nitriles can be used as starting materials to fabricate DBAs under mild and green conditions. The reaction kinetics has been investigated, which reveals that the PtMo WNWs show superior activity in the conversion of imines into amines. This study provides a practical advancement in the preparation of amines. Moreover, the protocol reported herein is feasible for the synthesis of worm-like nanostructures with designed composition for various catalytic applications.
- Lu, Shuanglong,Xu, Pengyao,Cao, Xueqin,Gu, Hongwei
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- Nitration of alkanes with nitric acid by vanadium-substituted polyoxometalates
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The nitration of alkanes by using nitric acid as a nitrating agent in acetic acid was efficiently promoted by vanadium-substituted Keggin-type phosphomolybdates such as [H4PVMo11O40], [H5PV2Mo10O40], and [H 6PV3Mo9O40] as catalyst precursors. A variety of alkanes including alkylbenzenes were nitrated to the corresponding nitroalkanes as major products in moderate yields with formation of oxygenated products under mild reaction conditions. The carbon-carbon bond cleavage reactions hardly proceeded. ESR, NMR, and IR spectroscopic data show that the vanadium-substituted polyoxometalate, for example, [H4PVMo 11O40], decomposes to form free vanadium species and [PMo12O40]3- Keggin anion. The reaction mechanism involving a radical-chain path is proposed. The polyoxometalates initially abstract the hydrogen of the alkane to form the alkyl radical and the reduced polyoxometalates. The reduced polyoxometalates subsequently react with nitric acid to produce the oxidized form and nitrogen dioxide. This step would be promoted mainly by the phosphomolybdates, [PMo12O 40]n-, and the vanadium cations efficiently enhance the activity. The nitrogen dioxide promotes the further formation of nitrogen dioxide and an alkyl radical. The alkyl radical is trapped by nitrogen dioxide to form the corresponding nitroalkane.
- Shinachi, Satoshi,Yahiro, Hidenori,Yamaguchi, Kazuya,Mizuno, Noritaka
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- Interfacial CoOx Layers on TiO2 as an Efficient Catalyst for Solvent-Free Aerobic Oxidation of Hydrocarbons
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Construction of efficient interfaces to improve the performance of supported metal catalysts is a challenging but effective technique. A newly synthesized catalyst with layered cobalt oxide on the surface of titania (layer-CoOx/TiO2) is highly selective towards the aerobic oxidation of C?H bonds in a series of hydrocarbons under sustainable conditions. The layer-CoOx/TiO2 easily outperforms the state-of-the-art noble metal catalysts and homogeneous cobalt salts used in industry. In-depth structural and functional characterization reveal that the layer-CoOx/TiO2 readily reacts with O2 for the adsorption and activation of C?H bonds. The layered structure of CoOx can maximize the interfacial effect of CoOx/TiO2 leading to a good performance for the oxidation of C?H bonds.
- Wang, Hai,Wang, Liang,Zhang, Jian,Wang, Chengtao,Liu, Ziyu,Gao, Xinhua,Meng, Xiangju,Yoo, Seung Jo,Kim, Jin-Gyu,Zhang, Wei,Xiao, Feng-Shou
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- Effects of the carbon support nature and ruthenium content on the performances of Ru/C catalysts in the liquid-phase hydrogenation of benzaldehyde to benzyl alcohol
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Abstract The hydrogenation of benzaldehyde in ethanol medium in the presence of Ru/C catalysts was shown to proceed with the preferential formation of benzyl alcohol without subsequent hydrodeoxygenation into toluene. An increase in ruthenium content of t
- Mironenko, Roman M.,Belskaya, Olga B.,Zaikovskii, Vladimir I.,Likholobov, Vladimir A.
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- Tetrahydropyranylation of alcohols and phenols using polystyrene supported lewis acids as catalysts
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Polystyrene supported TiCl4 (Ps-TiCl4) and polystyrene supported FeCl3(Ps-FeCl3) were prepared by coordinating Lewis acids with polystyrene. The catalysts were characterized by TGA, BET, SEM, IR and pyridine-adsorbed IR. The loading of Ps-TiCl4 and Ps-FeCl3 were 0.35 and 0.3 mmol·g-1 respectively. Both catalysts were found to be efficient for the tetrahydropyranylation and detetrahydropyranylation of various alcohols and phenols in different solvents. Two catalysts can be recovered and reused for five times with good activity. Polystyrene supported TiCl4 (Ps-TiCl4) and polystyrene supported FeCl3(Ps-FeCl 3) were prepared by coordinating Lewis acids with polystyrene. The catalysts were characterized by TGA, BET, SEM, IR and pyridine-adsorbed IR. The loading of Ps-TiCl4 and Ps-FeCl3 were 0.35 and 0.3 mmol·g-1 respectively. Both catalysts were found to be efficient for the tetrahydropyranylation and detetrahydropyranylation of various alcohols and phenols in different solvents. Two catalysts can be recovered and reused for five times with good activity. Copyright
- Zhang, Yi,Dou, Qianqian,Liu, Yuan,Dai, Liyan,Wang, Xiaozhong,Chen, Yingqi
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- New CNN-type ruthenium pincer NHC complexes. Mild, efficient catalytic hydrogenation of esters
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Figure Presented: New pincer ruthenium complexes (2-6) based on the new bipyridine-NHC ligand 1 were prepared and studied, resulting in an efficient catalytic hydrogenation of esters to the corresponding alcohols under mild conditions. Reaction of the ligand 1 with RuH(Cl)CO(PPh3) 3, followed by reaction with one equivalent of the base KHMDS, gave the mixed phosphine-NHC complex 2, incorporating a C-H-activated bipyridine ligand. Complex 2 has an octahedral structure containing two phosphorus atoms trans to each other, a hydride trans to the NHC ligand, and CO trans to the C-H-activated carbon of the bipyridine ligand. Using the precursor complex Ru(p-cymene)Cl2(CO), reaction with 1 followed by treatment of the intermediate product with one equivalent of KHMDS resulted in formation of the dichloride pincer complexes 3a and 3b, which are in equilibrium, as indicated by variable-temperature 1H NMR. Complex 3a is an octahedral, neutral, and symmetric complex with the CO ligand positioned trans to the central pyridine group of the pincer ligand and the two chlorides trans to each other, as indicated by single-crystal X-ray diffraction. Complex 3b is cationic, with an outer-sphere chloride. Reaction of the NHC ligand 1 with LiHMDS at low temperature followed by addition of RuH(Cl)CO(PPh3)3 resulted in the mixed phosphine-NHC complex 4, which has an octahedral structure containing phosphorus trans to the hydride, a CO trans to the NHC ligand, and an outer-sphere chloride. Chloride substitution by BArF- gave the X-ray-characterized complex 5. Deprotonation of complex 4 with KHMDS resulted in formation of the dearomatized complex 6. The in situ prepared 6 (from complex 4 and an equivalent of base) is among the best catalysts known for the hydrogenation of nonactivated esters to the corresponding alcohols under mild conditions.
- Fogler, Eran,Balaraman, Ekambaram,Ben-David, Yehoshua,Leitus, Gregory,Shimon, Linda J.W.,Milstein, David
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- n-Butyllithium (1 mol %)-catalyzed Hydroboration of Aldehydes and Ketones with Pinacolborane
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A practical and efficient protocol for the hydroboration of aldehydes and ketones using a pinacolborane and alkyl lithium system is demonstrated. A systematic evaluation showed that 1 mol % n-butyllithium afforded catalyzed hydroboration of aldehydes and ketones in a short reaction time under ambient conditions. Excellent yield, functional group tolerance, short reaction time, low catalyst loading, and gram-scale synthesis are the salient features of the proposed protocol.
- Yang, Su Jin,Jaladi, Ashok Kumar,Kim, Jea Ho,Gundeti, Shankaraiah,An, Duk Keun
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- OXIDATIVE Si-C BOND CLEAVAGE OF ORGANOTRIFLUOROSILANES INVOLVING ORGANIC-GROUP MIGRATION FROM HYPERCOORDINATE SILICON TO OXYGEN
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Various organotrifluorosilanes react with trimethylamine-N-oxide without catalyst to give the corresponding alcohols in high yields under mild conditions.Stereospecific nature of the reaction is suggestive of the involvment of intramolecular 1,2-organic-group migration from hypercoordinate silicon to oxygen.
- Sato, Kazuhiko,Kira, Mitsuo,Sakurai, Hideki
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- Design of mesoporous aluminosilicates supported (1R,2S)-(-)-ephedrine: Evidence for the main factors influencing catalytic activity in the enantioselective alkylation of benzaldehyde with diethylzinc
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(-)-Ephedrine, used as a model β-amino alcohol, was covalently anchored on mesoporous micelle templated aluminosilicates (Al-MTS) through nucleophilic substitution of halogenoalkyl(aryl)silane chains previously grafted on the surface. The covalent graftin
- Abramson,Lasperas,Brunel
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- Deamination of N,O-Dialkylhydroxylamines via N-Nitroso-N,O-dialkylhydroxylamines: a New Reaction
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N-Nitroso-N,O-dialkylhydroxylamines undergo acid catalysed deaminative solvolysis in aqueous solution.
- Maskill, H.,Menneer, Iain D.,Smith, David I.
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- Transformation of benzonitrile into benzyl alcohol and benzoate esters in supercritical alcohols
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The reactions of benzonitrile in supercritical methanol, ethanol, and 2-propanol were investigated under non-catalytic conditions. In supercritical methanol, benzonitrile was converted to methyl benzoate in high yield. The esterification reaction also occurred in supercritical ethanol to afford ethyl benzoate in moderate yield. The esterification could occur via a route analogous to the Pinner reaction. On the other hand, benzonitrile in supercritical 2-propanol yielded no ester. Benzyl alcohol was the major product in supercritical 2-propanol. We investigated the reaction of the C{double bond, long}N bond in supercritical 2-propanol. In supercritical 2-propanol, N-benzylideneaniline was transferred to the reduction product (N-benzylaniline) and hydrolysis products (benzyl alcohol and aniline). The hydrolysis reaction was restricted when the reaction was carried out in supercritical 2-propanol with a low water content. This indicates that the water in the 2-propanol acts as a reagent for the hydrolysis of the C{double bond, long}N bond. These results suggested the following reaction process: C6H5C{triple bond, long}N→C6H5CH{double bond, long}NH→C6H5CHO→C6H5CH2OH.
- Kamitanaka, Takashi,Yamamoto, Kenji,Matsuda, Tomoko,Harada, Tadao
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- Why does alkylation of the N-H functionality within M/NH bifunctional Noyori-type catalysts lead to turnover?
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Molecular metal/NH bifunctional Noyori-type catalysts are remarkable in that they are among the most efficient artificial catalysts developed to date for the hydrogenation of carbonyl functionalities (loadings up to ～10-5 mol %). In addition, these catalysts typically exhibit high C=0/C=C chemo- and enantioselectivities. This unique set of properties is traditionally associated with the operation of an unconventional mechanism for homogeneous catalysts in which the chelating ligand plays a key role in facilitating the catalytic reaction and enabling the aforementioned selectivities by delivering/accepting a proton (H+) via its N-H bond cleavage/formation. A recently revised mechanism of the Noyori hydrogenation reaction (Dub, P. A et al. J. Am. Chem. Soc. 2014,136,3505) suggests that the N-H bond is not cleaved but serves to stabilize the turnover-determining transition states (TDTSs) via strong N-H···O hydrogen-bonding interactions (HBIs). The present paper shows that this is consistent with the largely ignored experimental fact that alkylation of the N-H functionality within M/NH bifunctional Noyori-type catalysts leads to detrimental catalytic activity. The purpose of this work is to demonstrate that decreasing the strength of this HBI, ultimately to the limit of its complete absence, are conditions under which the same alkylation may lead to beneficial catalytic activity.
- Dub, Pavel A.,Scott, Brian L.,Gordon, John C.
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- Oxidation of toluene and other examples of Ci￡H bond activation by CdO2 and ZnO2 nanoparticles
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Nanoparticles of CdO2 and ZnO2 are shown to oxidize toluene primarily to benzaldehyde in the 160-180 °C range, around which temperature the nanoparticles decompose to give the oxides. The product selectivity and other features of the
- Lingampalli,Gupta, Uttam,Gautam, Ujjal K.,Rao
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- Non-Pincer-Type Manganese Complexes as Efficient Catalysts for the Hydrogenation of Esters
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Catalytic hydrogenation of carboxylic acid esters is essential for the green production of pharmaceuticals, fragrances, and fine chemicals. Herein, we report the efficient hydrogenation of esters with manganese catalysts based on simple bidentate aminophosphine ligands. Monoligated Mn PN complexes are particularly active for the conversion of esters into the corresponding alcohols at Mn concentrations as low as 0.2 mol % in the presence of sub-stoichiometric amounts of KOtBu base.
- van Putten, Robbert,Uslamin, Evgeny A.,Garbe, Marcel,Liu, Chong,Gonzalez-de-Castro, Angela,Lutz, Martin,Junge, Kathrin,Hensen, Emiel J. M.,Beller, Matthias,Lefort, Laurent,Pidko, Evgeny A.
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- Acetonyltriphenylphosphonium bromide and its polymer-supported analogues as catalysts in protection and deprotection of alcohols as alkyl vinyl ethers
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Both acetonyltriphenylphosphonium bromide (ATPB, 1) and poly-p-styryldiphenylacetonylphosphonium bromide (A) were effective catalysts in the protection of alcohols as THP, THF, and EE ethers as well as the cleavage of THP, THF, and EE ethers to the corresponding alcohols. They could be applied to 1°, 2° and 3° alcohols, phenol and acid-labile alcohols. Both ATPB and catalyst A are excellent catalysts in the present study. It needed only 1×10-2-1.25×10-2 mol equiv. of the polymer-supported catalyst A in the reactions.
- Hon, Yung-Son,Lee, Chia-Fu,Chen, Rong-Jiunn,Szu, Ping-Hui
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- Cu and boron doped carbon nitride for highly selective oxidation of toluene to benzaldehyde
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A novel Cu and boron doped graphitic carbon nitride catalyst (Cu-CNB) was synthesized using cheap precursors and systematically characterized. The selective oxidation of toluene proceeded very smoothly over the catalyst at 70 °C using tert-butyl hydropero
- Han, Hongling,Ding, Guodong,Wu, Tianbin,Yang, Dexin,Jiang, Tao,Han, Buxing
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- Highly chemoselective reduction of imines using a AuNPore/PhMe2SiH/water system and its application to reductive amination
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Abstract An unusually strong affinity of unsupported nanoporous gold (AuNPore) towards aldimines and ketimines has been demonstrated. By using PhMe2SiH and water as a hydrogen source and AuNPore as a catalyst, ketimines and aldimines can be reduced to the corresponding amines in high chemical yields under mild conditions. This system was also applied to the reductive amination of aldehydes and ketones.
- Takale, Balaram S.,Tao, Shanmou,Yu, Xiaoqiang,Feng, Xiujuan,Jin, Tienan,Bao, Ming,Yamamoto, Yoshinori
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- ORGANOCERIUM REAGENTS FROM IODINE ACTIVATED CERIUM METAL AND ORGANIC IODIDES: THEIR REACTIONS WITH CARBONYL COMPOUNDS
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Cerium metal activated by a trace of iodine reacted smoothly with alkyl, allyl, and aryl iodides to give the corresponding organocerium reagents.The reaction of the organocerium reagents thus prepared in situ with carbonyl compounds gave not only Grignard-type adducts but also reduction and reductive coupling products.
- Fukuzawa, Shin-ichi,Fujinami, Tatsuo,Sakai, Shizuyoshi
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- Transfer Hydrogenation of Ketones and Imines with Methanol under Base-Free Conditions Catalyzed by an Anionic Metal-Ligand Bifunctional Iridium Catalyst
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An anionic iridium complex [Cp*Ir(2,2′-bpyO)(OH)][Na] was found to be a general and highly efficient catalyst for transfer hydrogenation of ketones and imines with methanol under base-free conditions. Readily reducible or labile substituents, such as nitro, cyano, and ester groups, were tolerated under present reaction conditions. Notably, this study exhibits the unique potential of anionic metal-ligand bifunctional iridium catalysts for transfer hydrogenation with methanol as a hydrogen source.
- Han, Xingyou,Li, Feng,Liu, Peng,Wang, Rongzhou,Xu, Jing
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- α-Deuterium Isotope Effects in Benzyl Halides. 2. Reaction of Nucleophiles with Substituted Benzyl Bromides. Evidence for a Change in Transition-State Structure with Electron-Donating Substituents
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Rates and α-D isotope effects have been determined for the following substrates and nucleophiles: p-methoxybenzyl bromide (Et3N, SCN-, N3-, OH-, S2O32-) benzyl bromide (Et3N, SCN-, N3-, OH-, S2O32-), and p-nitrobenzyl bromide (Et3N, SCN-, N3-, S2O32-).In nearly all cases the second-order rate constant for each nucleophile goes though a minimum for the unsubstituted compound while the α-D isotope increases monotonically in the sequence p-NO2>p-H>p-OCH3.These results are consistent with an increasing "looseness" of the SN2 transition state as the substituent on the aromatic ring becomes more electron donating.
- Vitullo, V.P.,Grabowski, J.,Sridharan, S.
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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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- Selective catalytic synthesis of bio-based high value chemical of benzoic acid from xylan with Co2MnO4@MCM-41 catalyst
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The efficient synthesis of bio-based chemicals using renewable carbon resources is of great significance to promote sustainable chemistry and develop green economy. This work aims to demonstrate that benzoic acid, an important high added value chemical in petrochemical industry, can be selectively synthesized using xylan (a typical model compound of hemicellulose). This novel controllable transformation process was achieved by selective catalytic pyrolysis of xylan and subsequent catalytic oxidation. The highest benzoic acid selectivity of 88.3 % with 90.5 % conversion was obtained using the 10wt%Co2MnO4@MCM-41 catalyst under the optimized reaction conditions (80 °C, 4 h). Based on the study of the model compounds and catalyst's characterizations, the reaction pathways for the catalytic transformation of xylan to bio-based benzoic acid were proposed.
- Fan, Minghui,He, Yuting,Li, Quanxin,Luo, Yuehui,Yang, Mingyu,Zhang, Yanhua,Zhu, Lijuan
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- Chemoselective (Hetero)Arene Electroreduction Enabled by Rapid Alternating Polarity
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Conventional chemical and even electrochemical Birch-type reductions suffer from a lack of chemoselectivity due to a reliance on alkali metals or harshly reducing conditions. This study reveals that a simpler avenue is available for such reductions by simply altering the waveform of current delivery, namely rapid alternating polarity (rAP). The developed method solves these issues, proceeding in a protic solvent, and can be easily scaled up without any metal additives or stringently anhydrous conditions.
- Hayashi, Kyohei,Griffin, Jeremy,Harper, Kaid C.,Kawamata, Yu,Baran, Phil S.
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p. 5762 - 5768
(2022/04/15)
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- Photophysics of Perylene Diimide Dianions and Their Application in Photoredox Catalysis
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The two-electron reduced forms of perylene diimides (PDIs) are luminescent closed-shell species whose photochemical properties seem underexplored. Our proof-of-concept study demonstrates that straightforward (single) excitation of PDI dianions with green
- Li, Han,Wenger, Oliver S.
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supporting information
(2021/12/23)
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- Supported Iridium Catalyst for Clean Transfer Hydrogenation of Aldehydes and Ketones using Methanol as Hydrogen Source
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The use of methanol as abundant and low-toxic hydrogen source under mild and clean conditions is promising for the development of safe and sustainable reduction processes, but remains a daunting challenge. This work presents a recyclable ZnO-supported Ir
- He, Guangke,Liu, Xiang,Wang, Jing,Ye, Sen,Zhu, Jiazheng,Zhu, Longfei
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- 3D structured TiO2-based aerogel photocatalyst for the high-efficiency degradation of toluene gas
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Photocatalytic technology is a green , environmentally friendly, energy-saving technology, which is considered to be an ideal method for removing volatile organic compounds (VOCs). At present, photocatalytic technology mostly uses powdered catalysts, which is not conducive to recycling and restricts the contact between the gas and catalyst. In this work, a three-dimensional (3D)-structured TiO2-based aerogel with TiO2 as the main body and all the components beneficial to photocatalysis was prepared for the first time. Under simulated sunlight irradiation, the toluene-removal rate of the Pt-loaded TiO2 and reduced graphene oxide (RGO) composite aerogel (denoted as Pt-TiO2/RGO aerogel, or PTA thereafter) was 60.47% higher than that of the pure RGO aerogel, and 56.03% higher than that of the bare TiO2 nanofibers. The block-shaped composite aerogel could be easily recycled, and the C/C0 of toluene using the recycled sample decreased by only 5.31% in the 5th run. The Pt-TiO2/RGO composite aerogel had the highest photocatalytic degradation rate of toluene with a relative humidity (RH) of 60-80%, which is conducive to the purification of VOCs in high-humidity areas. The 3D aerogel enriches the contact between the solid photocatalyst and the toluene molecules, and also solves the problem of low adhesion between the catalyst and the carrier. This work provides a new perspective for the efficient removal of toluene gas by constructing a highly active 3D TiO2 aerogel with an increased gas-solid reaction rate.
- Dai, Li,Guan, Jie,Li, Shijie,Li, Xueying,Yu, Wei,Zhang, Li
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p. 2272 - 2281
(2022/02/16)
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- Hydroboration of Nitriles, Esters, and Carbonates Catalyzed by Simple Earth-Abundant Metal Triflate Salts
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During the past decade earth-abundant metals have become increasingly important in homogeneous catalysis. One of the reactions in which earth-abundant metals have found important applications is the hydroboration of unsaturated C?C and C?X bonds (X=O or N). Within these set of transformations, the hydroboration of challenging substrates such as nitriles, carbonates and esters still remain difficult and often relies on elaborate ligand designs and highly reactive catalysts (e. g., metal alkyls/hydrides). Here we report an effective methodology for the hydroboration of challenging C≡N and C=O bonds that is simple and applicable to a wide set of substrates. The methodology is based on using a manganese(II) triflate salt that, in combination with commercially available potassium tert-butoxide and pinacolborane, catalyzes the hydroboration of nitriles, carbonates, and esters at room temperature and with near quantitative yields in less than three hours. Additional studies demonstrated that other earth-abundant metal triflate salts can facilitate this reaction as well, which is further discussed in this report.
- Thenarukandiyil, Ranjeesh,Satheesh, Vanaparthi,Shimon, Linda J. W.,de Ruiter, Graham
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p. 999 - 1006
(2021/03/30)
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- Responsive Emulsions for Sequential Multienzyme Cascades
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Multienzyme cascade biocatalysis is an efficient synthetic process, avoiding the isolation/purification of intermediates and shifting the reaction equilibrium to the product side. However, multienzyme systems are often limited by their incompatibility and cross-reactivity. Herein, we report a multi-responsive emulsion to proceed multienzyme reactions sequentially for high reactivity. The emulsion is achieved using a CO2, pH, and thermo-responsive block copolymer as a stabilizer, allowing the on-demand control of emulsion morphology and phase composition. Applying this system to a three-step cascade reaction enables the individual optimal condition for each enzyme, and a high overall conversion (ca. 97 % of the calculated limit) is thereby obtained. Moreover, the multi-responsiveness of the emulsion allows the facile and separate yielding/recycling of products, polymers and active enzymes. Besides, the system could be scaled up with a good yield.
- Sun, Zhiyong,Zhao, Qingcai,Haag, Rainer,Wu, Changzhu
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supporting information
p. 8410 - 8414
(2021/03/09)
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- Membrane transport inspired hydrolysis of non-activated esters at near physiological pH
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A positively charged micelle loaded with substrates was transported selectively to the reaction site (cathode) to promote the proximity and localization of the reactants (ester and hydroxide). The guided vehicular delivery coupled with electrolysis allows the hydrolysis of non-activated esters at near physiological pH with significant yields along with recyclability.
- De Sarkar, Suman,Mahanty, Kingshuk,Mandal, Raki,Mandal, Subhendu,Tarafdar, Pradip K.
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supporting information
p. 11088 - 11091
(2021/10/30)
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- An asymmetric Salamo-based Zn complex supported on Fe3O4MNPs: a novel heterogeneous nanocatalyst for the silyl protection and deprotection of alcohols under mild conditions
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In this study, a magnetic asymmetric Salamo-based Zn complex (H2L = salen type di-Schiff bases)-supported on the surface of modified Fe3O4(Fe3O4@H2L-Zn) as a new catalyst was designed and characterizedvianumerous analytical techniques such as FT-IR spectroscopy, XRD, EDS, ICP-AES, SEM, TEM, TGA and VSM. An efficient and sustainable synthetic protocol has been presented for the synthesis of silyl ether substructuresviathe silyl protection of alcohols under mild conditions. The synthetic protocol involves a two-component solvent-free reaction between various hydroxyl-bearing substrates and hexamethyldisilazane (HMDS) as an inexpensive silylating agent using Fe3O4@H2L-Zn MNPs as a magnetically separable, recyclable and reusable heterogeneous catalyst. Fe3O4@H2L-Zn MNPs were also applied for the removal of silyl protecting groups from hydroxyl functions using water in CH2Cl2under green conditions. The catalyst demonstrated good to excellent catalytic yield efficiency for both the reactions compared to the commercial metal-based catalysts under green conditions for a wide range of substrates.
- Yao, Hongyan,Wang, Yongsheng,Razi, Maryam Kargar
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p. 12614 - 12625
(2021/04/14)
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- Manganese-Catalyzed Hydrogenation of Sclareolide to Ambradiol
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The hydrogenation of (+)-Sclareolide to (?)-ambradiol catalyzed by a manganese pincer complex is reported. The hydrogenation reaction is performed with an air- and moisture-stable manganese catalyst and proceeds under relatively mild reaction conditions at low manganese and base loadings. A range of other esters could be successfully hydrogenated leading to the corresponding alcohols in good to quantitative yields using this easy-to-make catalyst. A scale-up experiment was performed leading to 99.3 % of the isolated yield of (?)-Ambradiol.
- Hashmi, A. Stephen K.,Lichtenberger, Niels,Oeser, Thomas,Schaub, Thomas,Schelwies, Mathias,Zubar, Viktoriia
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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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- Experimental Evidence of syn H-N-Fe-H Configurational Requirement for Iron-Based Bifunctional Hydrogenation Catalysts
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Iron hydrides supported by a pincer ligand of the type HN(CH2CH2PR2)2 (RPNHP) are versatile hydrogenation catalysts. Previous efforts have focused on using CO as an additional ligand to stabilize the hydride species. In this work, CO is replaced with isocyanide ligands, leading to the isolation of two different types of iron hydride complexes: (RPNHP)FeH(CNR′)(BH4) (R = iPr, R′ = 2,6-Me2C6H3, tBu; R = Cy, R′ = 2,6-Me2C6H3) and [(iPrPNHP)FeH(CNtBu)2]X (X = BPh4, Br, or a mixture of Br and BH4). The neutral iron hydrides are capable of catalyzing the hydrogenation of PhCO2CH2Ph to PhCH2OH, although the activity is lower than for (iPrPNHP)FeH(CO)(BH4). The cationic iron hydrides are active hydrogenation catalysts only for more reactive carbonyl substrates such as PhCHO, and only when the NH and FeH hydrogens are syn to each other. The cationic species and their synthetic precursors [(iPrPNHP)FeBr(CNtBu)2]X (X = BPh4, Br) can have different configurations for the isocyanide ligands (cis or trans) and the H-N-Fe-H(Br) unit (syn or anti). Unlike tetraphenylborate, the bromide counterion participates in a hydrogen-bonding interaction with the NH group, which influences the relative stability of the cis,anti and cis,syn isomers. These structural differences have been elucidated by X-ray crystallography, and the geometric isomerization processes have been studied by NMR spectroscopy.
- Dai, Huiguang,Guan, Hairong,Krause, Jeanette A.,Li, Weishi
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p. 6521 - 6535
(2021/05/31)
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- A method of synthesis of alcohols
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The present invention belongs to the field of organic synthesis technology, specifically a synthesis method of an alcohol; the present invention is under the catalytic action of tert-butanol lithium, with ester compounds and pinacol borane as raw materials, tetrahydrofuran as a solvent, reacted at 100 ° C for 24h, followed by adding 2mol / LNaOH / MeOH solution, stirred at room temperature overnight to obtain alcohol compounds; the raw materials of the present invention are of extensive sources or easy to prepare, the reaction conditions are relatively mild and do not require a large number of / cumbersome additives, in addition to the tert-butanol lithium catalyst is simple, And the prepared alcohol compounds are of high quality and high separation yield.
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Paragraph 0025-0030; 0085-0088
(2022/01/10)
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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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- Scope and limitations of biocatalytic carbonyl reduction with white-rot fungi
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The reductive activity of various basidiomycetous fungi towards carbonyl compounds was screened on an analytical level. Some strains displayed high reductive activities toward aromatic carbonyls and aliphatic ketones. Utilizing growing whole-cell cultures of Dichomitus albidofuscus, the reactions were up-scaled to a preparative level in an aqueous system. The reactions showed excellent selectivities and gave the respective alcohols in high yields. Carboxylic acids were also reduced to aldehydes and alcohols under the same conditions. In particular, benzoic, vanillic, ferulic, and p-coumaric acid were reduced to benzyl alcohol, vanillin, dihydroconiferyl alcohol and 1-hydroxy-3-(4-hydroxyphenyl)propan, respectively.
- Zhuk, Tatyana S.,Skorobohatko, Oleksandra S.,Albuquerque, Wendell,Zorn, Holger
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supporting information
(2021/02/02)
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- Hydroboration Reaction and Mechanism of Carboxylic Acids using NaNH2(BH3)2, a Hydroboration Reagent with Reducing Capability between NaBH4and LiAlH4
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Hydroboration reactions of carboxylic acids using sodium aminodiboranate (NaNH2[BH3]2, NaADBH) to form primary alcohols were systematically investigated, and the reduction mechanism was elucidated experimentally and computationally. The transfer of hydride ions from B atoms to C atoms, the key step in the mechanism, was theoretically illustrated and supported by experimental results. The intermediates of NH2B2H5, PhCH= CHCOOBH2NH2BH3-, PhCH= CHCH2OBO, and the byproducts of BH4-, NH2BH2, and NH2BH3- were identified and characterized by 11B and 1H NMR. The reducing capacity of NaADBH was found between that of NaBH4 and LiAlH4. We have thus found that NaADBH is a promising reducing agent for hydroboration because of its stability and easy handling. These reactions exhibit excellent yields and good selectivity, therefore providing alternative synthetic approaches for the conversion of carboxylic acids to primary alcohols with a wide range of functional group tolerance.
- Wang, Jin,Ju, Ming-Yue,Wang, Xinghua,Ma, Yan-Na,Wei, Donghui,Chen, Xuenian
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p. 5305 - 5316
(2021/04/12)
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- Development of effective bidentate diphosphine ligands of ruthenium catalysts toward practical hydrogenation of carboxylic acids
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Hydrogenation of carboxylic acids (CAs) to alcohols represents one of the most ideal reduction methods for utilizing abundant CAs as alternative carbon and energy sources. However, systematic studies on the effects of metal-to-ligand relationships on the catalytic activity of metal complex catalysts are scarce. We previously demonstrated a rational methodology for CA hydrogenation, in which CA-derived cationic metal carboxylate [(PP)M(OCOR)]+ (M = Ru and Re; P = one P coordination) served as the catalyst prototype for CA self-induced CA hydrogenation. Herein, we report systematic trial- and-error studies on how we could achieve higher catalytic activity by modifying the structure of bidentate diphosphine (PP) ligands of molecular Ru catalysts. Carbon chains connecting two P atoms as well as Ar groups substituted on the P atoms of PP ligands were intensively varied, and the induction of active Ru catalysts from precatalyst Ru(acac)3 was surveyed extensively. As a result, the activity and durability of the (PP)Ru catalyst substantially increased compared to those of other molecular Ru catalyst systems, including our original Ru catalysts. The results validate our approach for improving the catalyst performance, which would benefit further advancement of CA self-induced CA hydrogenation.
- Saito, Susumu,Wen, Ke,Yoshioka, Shota
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p. 1510 - 1524
(2021/06/18)
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- Bis-(triphenylphosphane) Aluminum Hydride: A Simple Way to Provide, Store, and Use Non-Polymerized Alane for Synthesis
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AlH3(PPh3)2 was synthesized as a stable solid being the first known 1 : 2 alane arylphosphane adduct. Although only weakly intra-molecularly coordinated, it displays as a molecular crystal significant inertness against atmospheric humidity and oxygen due to strong steric screening of the alane unit. The compound readily dissociates PPh3 in solution allowing for its use as a Lewis acidic reducing agent. These features lead to an easy to store, easy to use reducing agent that may enable the quantitative investigation of aluminum hydride chemistry including reduction, complexation and hydroalumination reactions. The structure contains two non-equivalent penta-coordinated aluminum centers that despite long Al?P distances of ca. 2.7 ? display unusually high quadrupolar coupling constants CQ of 25.1 and 26.5 in 27Al solid state NMR measurements. The product was also tested as a reducing agent on a small set of selected compounds with various functional groups.
- Anders, Martin,Brendler, Erica,Kaiser, Stefan,Mertens, Florian,Pollex, Rolf,Sandig-Predzymirska, Lesia,Schumann, Erik,Schwarzer, Anke
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p. 1193 - 1198
(2021/08/31)
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- Intercepting a transient non-hemic pyridine: N -oxide Fe(iii) species involved in OAT reactions
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In the context of bioinspired OAT catalysis, we developed a tetradentate dipyrrinpyridine ligand, a hybrid of hemic and non-hemic models. The catalytic activity of the iron(iii) derivative was investigated in the presence of iodosylbenzene. Unexpectedly, MS, EPR, M?ssbauer, UV-visible and FTIR spectroscopic signatures supported by DFT calculations provide convincing evidence for the involvement of a relevant FeIII-O-NPy active intermediate. This journal is
- Vo, Nhat Tam,Herrero, Christian,Guillot, Régis,Inceoglu, Tanya,Leibl, Winfried,Clémancey, Martin,Dubourdeaux, Patrick,Blondin, Geneviève,Aukauloo, Ally,Sircoglou, Marie
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supporting information
p. 12836 - 12839
(2021/12/10)
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- Synthesis, crystal and structural characterization, Hirshfeld surface analysis and DFT calculations of three symmetrical and asymmetrical phosphonium salts
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Three stable phosphonium salts of 1,4-butanediylebis(triphenylphosphonium) dibromide I, butane-4?bromo-1-(triphenylphosphonium) bromide II and 1,3-propanediylbis(triphenylphosphonium) tetrahydroborate III were synthesized and structurally characterized. Single crystal X-ray diffraction analysis, spectroscopic methods and thermal analysis methods were used for the characterization of titled compounds. Crystallographic data showed that compound I crystallized in the triclinic crystal system with Pī space group and compound II crystallized in the monoclinic crystal system with P21/c space group. The crystal packing structures of I and II were stabilized by various intermolecular interactions, especially of C–H···π contacts. The molecular Hirshfeld surface analysis and 2D fingerprint revealed that the C···H contacts have 24.3% and 18.4% contributions in the crystal packings of compounds I and II, respectively. In addition, the H···Br (28.5%) contact has a considerable contribution to the crystal architecture of compound II. Theoretical studies were performed by DFT method to investigate the structural properties of the titled compounds. The isotopic ratio of boron in tetrahydroborate anion of compound III calculated by 1H NMR spectroscopy. The isotopic ratio for 10B/11B was 19.099 / 80.900%. Reduction of some carbonyl compounds to corresponding alcohols was performed by compound III and the optimum conditions were determined.
- Delaram, Behnaz,Gholizadeh, Mostafa,Makari, Faezeh,Nokhbeh, Seyed Reza,Salimi, Alireza
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- A mild and selective Cu(II) salts-catalyzed reduction of nitro, azo, azoxy, N-aryl hydroxylamine, nitroso, acid halide, ester, and azide compounds using hydrogen surrogacy of sodium borohydride
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The first mild, in situ, single-pot, high-yielding well-screened copper (II) salt-based catalyst system utilizing the hydrogen surrogacy of sodium borohydride for selective hydrogenation of a broad range of nitro substrates into the corresponding amine under habitancy of water or methanol like green solvents have been described. Moreover, this catalytic system can also activate various functional groups for hydride reduction within prompted time, with low catalyst-loading, without any requirement of high pressure or molecular hydrogen supply. Notably, this system explores a great potential to substitute expensive traditional hydrogenation methodologies and thus offers a greener and simple hydrogenative strategy in the field of organic synthesis.
- Kalola, Anirudhdha G.,Prasad, Pratibha,Mokariya, Jaydeep A.,Patel, Manish P.
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supporting information
p. 3565 - 3589
(2021/10/12)
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- Ruthenium (II) complexes with C2- and C1-symmetric bis-(+)-camphopyrazole ligands and their evaluation in catalytic transfer hydrogenation of aldehydes
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Ruthenium (II) piano-stool complexes with bis-(+)-camphopyrazole ligands of C2 and C1 symmetry were prepared in good yields (66–98%). New C2-C1 ligands and complexes were characterized by multinuclear NMR spectroscopy, FT-IR and elemental analysis. The catalytic performance of the Ru(II)-bis-(+)-camphopyrazole complexes in the transfer hydrogenation of benzaldehyde and valeraldehyde using isopropanol/potassium carbonate and formic acid/triethylamine mixtures as hydrogen donors, was evaluated, resulting in moderate yields (>54%) for the reduction to the desired primary alcohols. The system with isopropanol as hydrogen source proved to be more selective than the analogous system using the azeotropic formic acid/triethylamine mixture, allowing benzyl alcohol to be obtained in quantitative yield (>99%) for a particular catalyst precursor. Furthermore, complexes with C2 symmetry ligands showed higher yields than those with C1 symmetry ligands in all of the evaluated systems.
- Agrifoglio, Giuseppe,Blanco, Christian O.,Dorta, Romano,Herrera, Alberto,Landaeta, Vanessa R.,Llovera, Ligia,Pastrán, Jesús,Venuti, Doménico
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supporting information
(2021/05/10)
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- Dual utility of a single diphosphine-ruthenium complex: A precursor for new complexes and, a pre-catalyst for transfer-hydrogenation and Oppenauer oxidation
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The diphosphine-ruthenium complex, [Ru(dppbz)(CO)2Cl2] (dppbz = 1,2-bis(diphenylphosphino)benzene), where the two carbonyls are mutually cis and the two chlorides are trans, has been found to serve as an efficient precursor for the synthesis of new complexes. In [Ru(dppbz)(CO)2Cl2] one of the two carbonyls undergoes facile displacement by neutral monodentate ligands (L) to afford complexes of the type [Ru(dppbz)(CO)(L)Cl2] (L = acetonitrile, 4-picoline and dimethyl sulfoxide). Both the carbonyls in [Ru(dppbz)(CO)2Cl2] are displaced on reaction with another equivalent of dppbz to afford [Ru(dppbz)2Cl2]. The two carbonyls and the two chlorides in [Ru(dppbz)(CO)2Cl2] could be displaced together by chelating mono-anionic bidentate ligands, viz. anions derived from 8-hydroxyquinoline (Hq) and 2-picolinic acid (Hpic) via loss of a proton, to afford the mixed-tris complexes [Ru(dppbz)(q)2] and [Ru(dppbz)(pic)2], respectively. The molecular structures of four selected complexes, viz. [Ru(dppbz)(CO)(dmso)Cl2], [Ru(dppbz)2Cl2], [Ru(dppbz)(q)2] and [Ru(dppbz)(pic)2], have been determined by X-ray crystallography. In dichloromethane solution, all the complexes show intense absorptions in the visible and ultraviolet regions. Cyclic voltammetry on the complexes shows redox responses within 0.71 to -1.24 V vs. SCE. [Ru(dppbz)(CO)2Cl2] has been found to serve as an excellent pre-catalyst for catalytic transfer-hydrogenation and Oppenauer oxidation.
- Mukherjee, Aparajita,Bhattacharya, Samaresh
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p. 15617 - 15631
(2021/05/19)
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- PNO ligand containing planar chiral ferrocene and application thereof
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The invention discloses a PNO ligand containing planar chiral ferrocene and application thereof. The PNO ligand containing planar chiral ferrocene is a planar chiral ferrocene-containing and phenol-containing PNO ligand as shown in a general formula (I) or (II) which is described in the specification, or a planar chiral ferrocene-containing and aryl-phosphoric-acid-containingPNO ligand containing as shown in a general formula (III) or (IV) which is described in the specification, or a planar chiral ferrocene-containing and carbon-chiral-phenol-containingPNO ligand as shown in a general formula (V) or (VI) which is described in the specification. The invention provides tridentate PNO ligands and processes for their complexation with transition metal salts or transition metal complexes; the introduction of salicylaldehyde and derivatives thereof, which are simple and easy to obtain, enables the ligands to have a bifunctionalization effect, and -OH in a formed catalyst has stronger acidity and is beneficial to combination with N/O in polar double bonds. Therefore, due to the bifunctionalization effect of the catalyst, the interaction between the catalyst and a substrate can be greatly improved, so a reaction can obtain higher catalytic activity and stereoselectivity.
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Paragraph 0114-0118
(2021/06/21)
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- A Water/Toluene Biphasic Medium Improves Yields and Deuterium Incorporation into Alcohols in the Transfer Hydrogenation of Aldehydes
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Deuterium labeling is an interesting process that leads to compounds of use in different fields. We describe the transfer hydrogenation of aldehydes and the selective C1 deuteration of the obtained alcohols in D2O, as the only deuterium source. Different aromatic, alkylic and α,β-unsaturated aldehydes were reduced in the presence of [RuCl(p-cymene)(dmbpy)]BF4, (dmbpy=4,4′-dimethyl-2,2′-bipyridine) as the pre-catalyst and HCO2Na/HCO2H as the hydrogen source. Moreover, furfural and glucose, were selectively reduced to the valuable alcohols, furfuryl alcohol and sorbitol. The processes were carried out in neat water or in a biphasic water/toluene system. The biphasic system allowed easy recycling, higher yields, and higher selective D incorporation (using D2O/toluene). The deuteration took place due to an efficient effective M–H/D+ exchange from D2O that allows the inversion of polarity of D+ (umpolung). DFT calculations that explain the catalytic behavior in water are also included.
- Ruiz-Casta?eda, Margarita,Santos, Lucía,Manzano, Blanca R.,Espino, Gustavo,Jalón, Félix A.
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supporting information
p. 1358 - 1372
(2021/03/16)
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- Iron-catalyzed chemoselective hydride transfer reactions
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A Diaminocyclopentadienone iron tricarbonyl complex has been applied in chemoselective hydrogen transfer reductions. This bifunctional iron complex demonstrated a broad applicability in mild conditions in various reactions, such as reduction of aldehydes over ketones, reductive alkylation of various functionalized amines with functionalized aldehydes and reduction of α,β-unsaturated ketones into the corresponding saturated ketones. A broad range of functionalized substrates has been isolated in excellent yields with this practical procedure.
- Coufourier, Sébastien,Ndiaye, Daouda,Gaillard, Quentin Gaignard,Bettoni, Léo,Joly, Nicolas,Mbaye, Mbaye Diagne,Poater, Albert,Gaillard, Sylvain,Renaud, Jean-Luc
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supporting information
(2021/06/07)
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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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- Platinum supported on nanosilica and fibrous nanosilica for hydrogenation reactions
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Platinum nanoparticles supported on nanosilica (NP) and fibrous nanosilica (dendritic fibrous nano-spheres, DFNS) were prepared by direct grafting of the Pt precursor onto the silanol groups or via a polyethylenimine (PEI) linker. From the SEM and TEM images the average diameter of the nanosilica and fibrous nanosilica (DFNS), was determined to be 21.4 and 503 nm, respectively. While surface areas as measured by ASAP is 463.4 m2 g?1 for DFNS and 142.5 m2 g?1 for the nanosilica. For the four Pt containing catalysts (Pt/NP, Pt/DFNS, Pt/PEI/NP and Pt/PEI/DFNS), a Pt loading between 1.35 × 1017 and 8.46 × 1017 Pt atoms per gram support were determined. The PEI-containing catalyst gave higher Pt-loading than the direct anchoring of the Pt onto the silanol groups of the support. The catalysts were further characterised ATR FTIR and XPS. After oxidation of the pre-catalysts 85% of the Pt was in the oxide form. While after reduction, ca. 82% the Pt supported on DFNS was in the metallic form. Reduction of the Pt supported on NP, resulted in 100% of the Pt in the Pt0 oxidation state. These catalysts were tested for the hydrogenation of C[dbnd]C and/or C[dbnd]O bonds in cyclohexene, benzaldehyde and cinnamaldehyde. The % conversion and product distribution will be discussed in term of diameter, surface area and Pt-loading.
- Erasmus, E.,Xantini, Z.
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- RhNPs supported onN-functionalized mesoporous silica: effect on catalyst stabilization and catalytic activity
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Amine and nicotinamide groups grafted on ordered mesoporous silica (OMS) were investigated as stabilizers for RhNPs used as catalysts in the hydrogenation of several substrates, including carbonyl and aryl groups. Supported RhNPs on functionalized OMS were prepared by controlled decomposition of an organometallic precursor of rhodium under dihydrogen pressure. The resulting materials were characterized thoroughly by spectroscopic and physical techniques (FTIR, TGA, BET, SEM, TEM, EDX, XPS) to confirm the formation of spherical rhodium nanoparticles with a narrow size distribution supported on the silica surface. The use of nicotinamide functionalized OMS as a support afforded small RhNPs (2.3 ± 0.3 nm), and their size and shape were maintained after the catalyzed acetophenone hydrogenation. In contrast, amine-functionalized OMS formed RhNP aggregates after the catalytic reaction. The supported RhNPs could selectively reduce alkenyl, carbonyl, aryl and heteroaryl groups and were active in the reductive amination of phenol and morpholine, using a low concentration of the precious metal (0.07-0.18 mol%).
- Pulido-Díaz, Israel T.,Serrano-Maldonado, Alejandro,López-Suárez, Carlos César,Méndez-Ocampo, Pedro A.,Portales-Martínez, Benjamín,Gutiérrez-Alejandre, Aída,Salas-Martin, Karla P.,Guerrero-Ríos, Itzel
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p. 3289 - 3298
(2021/03/16)
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- (Hexamethylbenzene)Ru catalysts for the Aldehyde-Water Shift reaction
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The Aldehyde-Water Shift (AWS) reaction uses H2O as a benign oxidant to convert aldehydes to carboxylic acids, producing H2, a valuable reagent and fuel, as its sole byproduct. (Hexamethylbenzene)RuIIcomplexes are demonstrated to have higher activity and selectivity (up to 95%) for AWS over disproportionation than previously reported catalysts.
- Phearman, Alexander S.,Moore, Jewelianna M.,Bhagwandin, Dayanni D.,Goldberg, Jonathan M.,Heinekey, D. Michael,Goldberg, Karen I.
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supporting information
p. 1609 - 1615
(2021/03/09)
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- Nitrosoarene-Catalyzed HFIP-Assisted Transformation of Arylmethyl Halides to Aromatic Carbonyls under Aerobic Conditions
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A rare metal-free nucleophilic nitrosoarene catalysis accompanied by highly hydrogen-bond-donor (HBD) solvent, 1,1,1,3,3,3-hexafluoro-2-propanol (HFIP), organocatalytically converts arylmethyl halides to aromatic carbonyls. This protocol offers an effective means to access a diverse array of aromatic carbonyls with good chemoselectivity under mild reaction conditions. The activation of arylmethyl halides by HFIP to generate stable carbocation and autoxidation of in situ generated hydroxylamine to nitrosoarene in the presence of atmospheric O2 are the keys to success.
- Pradhan, Suman,Sharma, Vishali,Chatterjee, Indranil
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p. 6148 - 6152
(2021/08/03)
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- Synthesis and catalytic activity of N-heterocyclic silylene (NHSi) iron (II) hydride for hydrosilylation of aldehydes and ketones
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A novel silylene supported iron hydride [Si, C]FeH (PMe3)3 (1) was synthesized by C (sp3)-H bond activation with zero-valent iron complex Fe (PMe3)4. Complex 1 was fully characterized by spectroscopic methods and single crystal X-ray diffraction analysis. To the best of our knowledge, 1 is the first example of silylene-based hydrido chelate iron complex produced through activation of the C (sp3)?H bond. It was found that complex 1 exhibited excellent catalytic activity for hydrosilylation of aldehydes and ketones. The catalytic system showed good tolerance and catalytic activity for the substrates with different functional groups on the benzene ring. It is worth mentioning that, the experimental results showed that both ketones and aldehydes could be reduced in good to excellent yields under the same catalytic conditions. Based on the experiments and literature reports, a possible catalytic mechanism was proposed.
- Du, Xinyu,Qi, Xinghao,Li, Kai,Li, Xiaoyan,Sun, Hongjian,Fuhr, Olaf,Fenske, Dieter
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- Core-shell Co-MOF-74@Mn-MOF-74 catalysts with Controllable shell thickness and their enhanced catalytic activity for toluene oxidation
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A series of core-shell Co-MOF-74@Mn-MOF-74 samples with different shell thicknesses were prepared by the seed growth method, which were characterized by powder X-ray diffraction (PXRD), thermogravimetric analysis (TGA), inductively coupled plasma mass spectrometry (ICP-MS), X-ray photoelectron spectroscopy, nitrogen adsorption-desorption and scanning electron microscopy (SEM). The shell thickness of these MOF samples were successfully controlled by adjusting the mass ratio between MnCl2·4H2O and Co-MOF-74. On this basis, these MOFs were applied to the catalytic oxidation of toluene. The results showed that with the growth of Mn-MOF-74 in the outer layer of Co-MOF-74, the oxidative selectivity of the substrate to benzaldehyde was greatly improved for the synergy between the core layer and shell layer. The conversion of toluene was 22.4%, and the selectivity of benzaldehyde was 98.1%. In addition, the catalyst can transform various substituted toluene into the corresponding aldehydes in highly selectivity and still keep good stability after four catalytic cycles. The selectivity of the corresponding aldehyde is generally above 80%.
- Gu, Xiangyu,Huang, Cheng,Xu, Zengchuang,Wu, Hao,Dong, Ruilan,Liu, Rui,Chen, Jing,Zhu, Hongjun
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- Microporous cobaltporphyrin covalent polymer mediated Co3O4@PNC nanocomposites for efficient catalytic C-H bond activation
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A Cobalt porphyrin conjugated porous polymer (Co/PCP) was obtained by hybrid polymerization of a mixture of Co(II)(5,10,15,20-tetrakis(4-bromophenyl)-21H,23H-porphyrin) (CoTBPP) and 5,10,15,20-tetrakis(4-bromophenyl)-21H,23H-porphyrin (TBPP) (3:7 M ratio) with the coupling reagent of p-phenyldiboric acid. This Co/PCP was carbonized at 400 °C and the obtained catalyst (denoted as Co3O4@PNC-400) was composed of Co3O4 nanoclusters wrapped in the nitrogen-carbon materials. This catalyst has an extremely high catalytic activity for the aerobic oxidation of C–H bonds. It can efficiently catalyze the oxidation of the C–H bonds in toluene and cyclohexane with high conversion and high selectivity of (alcohol + aldehyde), (alcohol + ketone) compounds, respectively. When heat-treated at 400 °C, the porous framework structure of the porphyrin polymer was partially retained, and the highly active Co3O4 nanoclusters were generated in situ. The reaction of C[dbnd]N to C–N and connection with the Co3O4 nanoclusters also occurred. Co3O4@PNC-400 has obvious synergistic catalytic effect between Co3O4 and nitrogen-carbon framework during the catalytic reaction. The defective structure caused by the migration of cobalt also greatly improved the catalytic activity. Co/PCPs with different cobalt contents were also synthesized and heat treated at different temperature. These catalysts were a new type of efficient C–H oxidation catalysts with excellent potential application value.
- Tan, Mingyang,Zhu, Liang,Liu, Hao,Fu, Yajun,Yin, Shuang-Feng,Yang, Weijun
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- Molybdenum Isomorphously Substituted Decatungstates as Robust and Renewable Photocatalysts for Visible Light-Driven Oxidation of Hydrocarbons by Molecular Oxygen
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This article reveals that molybdenum (Mo) heteroatoms isomorphously substituted decatungstates (Mo–DTs) can be conveniently synthesized via copolymerization of tungstate and molybdate in acidic solution. A series of characterizations support that the inco
- Yang, Bo,Zhang, Huanhuan,Wan, Feifei,Deng, Youer,Jiang, Dabo,Zhang, Qiao,Liu, Yachun,Zhang, Chao,Fu, Zaihui
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p. 2253 - 2261
(2021/03/15)
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- Photo-tunable oxidation of toluene and its derivatives catalyzed by TBATB
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In this report, tetrabutylammonium tribromide (TBATB) was introduced as an efficient visible light active catalyst to carry out the aerobic oxidation of toluene, its derivatives, and some of methyl arenes to benzaldehydes, benzoic acids and ketones in good to high yields. All the oxidation reactions were performed under mild conditions using oxygen as a green oxidant, a catalytic amount of TBATB under blue (460 nm), royal blue (430 nm), and violet LED (400 nm) irradiation. It was found that the reactions selectivity was significantly affected by changing the solvent (from CH3CN to EtOAc) and LED wavelength (from blue to violet). In the following, our mechanistic studies revealed that the visible light oxidation of toluenes and methyl arenes over TBATB could be following a benzyl peroxy radical intermediate.
- Mardani, Atefeh,Kazemi, Foad,Kaboudin, Babak
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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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- An efficient chromium(iii)-catalyzed aerobic oxidation of methylarenes in water for the green preparation of corresponding acids
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A highly efficient method to oxidize methylarenes to their corresponding acids with a reusable Cr catalyst was developed. The reaction can be carried out in water with 1 atm oxygen and K2S2O8as cooxidants, proceeds under green and mild conditions, and is suitable for the oxidation of both electron-deficient and electron-rich methylarenes, including heteroaryl methylarenes, even at the gram level. The excellent result, together with its simplicity of operation and the ability to continuously reuse the catalyst, makes this new methodology environmentally benign and cost-effective. The generality of this methodology gives it the potential for use on an industrial scale. Differing from the accepted oxidation mechanism of toluene, GC-MS studies and DFT calculations have revealed that the key benzyl alcohol intermediate is formed under the synergetic effect of the chromium and molybdenum in the Cr catalyst, which can be further oxidized to afford benzaldehyde and finally benzoic acid.
- Jiang, Feng,Liu, Shanshan,Wei, Yongge,Yan, Likai,Yu, Han,Zhao, Wenshu
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supporting information
p. 12413 - 12418
(2021/09/28)
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- Bimetallic oxide nanoparticles confined in ZIF-67-derived carbon for highly selective oxidation of saturated C–H bond in alkyl arenes
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Zeolite imidazolate frameworks (ZIFs) have recently emerged as an ideal type of carbon precursors with abundant tailorability. In this work, a series of ZIF-derived porous carbon catalysts have been prepared with encapsulation of bimetallic oxide nanoparticles via simple thermal treatment. The composition and structure of these catalysts were confirmed in detail by different characterization methods. The bimetallic oxide (Mn/Co, Fe/Co, and Cu/Co) nanoparticles were encapsulated in the nitrogen-doped graphitized carbon matrix. Moreover, the hierarchically porous structure and carbon defects were successfully constructed in the carbon catalysts. Additionally, in the selective oxidation of saturated C–H bonds in alkyl arenes, the carbon catalysts demonstrate outstanding performance for the oxidation of C–H bonds to corresponding carboxyl groups. This was due to their unique structure can greatly promote mass transfer and molecular oxygen activation, resulting in high conversion and high selectivity. Remarkably, this work here could also provide a novel strategy to the controllable synthesis of metal–organic frameworks (MOFs)-derived carbon catalysts for enhanced performance in heterogeneous catalysis.
- Huang, Cheng,Su, Xiaoyan,Gu, Xiangyu,Liu, Rui,Zhu, Hongjun
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- Selective aerobic oxidation of toluene to benzaldehyde catalyzed by covalently anchored N-hydroxyphthalimide and cobaltous ions
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Selective oxidation of toluene to benzaldehyde via dioxygen is of great significance industrially but suffers from a severely low selectivity due to a much higher reactivity of the desired product than the reactant. A combination of homogeneous N-hydroxyphthalimide (NHPI) and cobaltous ions was found active and selective for the transformation from toluene to benzaldehyde in the presence of hexafloropropan-2-ol. In this work, homogeneous NHPI was covalently anchored onto the surface of commercial mesoporous SiO2 to facilitate the separation and recovery of the catalyst, aiming at a possible industrial application. The grafting bonds were well confirmed by FT-IR, TGA and XP spectra, and the density of > N–OH groups anchored was up to 0.6 mmol/g in the immobilized NHPI catalysts. The resulting catalysts exhibited an excellent activity for selective oxidation of toluene to benzaldehyde, and there was no appreciable loss in catalytic activity observed after repeated evaluations, suggesting a promising prospect for its further investigation and possible application.
- Xu, Jinyang,Shi, Guojun,Liang, Yuxin,Lu, Qiuting,Ji, Lijun
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- Confinement of Au3+-rich clusters by using Silicalite-1 for selective solvent-free oxidation of toluene
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The selective oxidation of primary carbon-hydrogen bonds in the methyl group of toluene to corresponding oxygenates is of immense significance. This transformation, however, remains challenging and often requires either extensive optimization of the prese
- Ge, Yuzhen,Huang, He,Liu, Yingcen,Lu, Rongwen,Shan, Yu,Song, Caicheng,Ye, Wanyue,Zhang, Shufen,Zhang, Xiaotong
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supporting information
p. 14710 - 14721
(2021/07/12)
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- Efficient catalytic oxidation of primary benzylic C[sbnd]H bonds with molecular oxygen catalyzed by cobalt porphyrins and N-hydroxyphthalimide (NHPI) in supercritical carbon dioxide
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The oxidation of benzylic C[sbnd]H bonds by metalloporphyrins in supercritical carbon dioxide (scCO2) has still limited. Herein, an efficient protocol of aerobic oxidation of primary benzylic C[sbnd]H bond by cobalt porphyrin and NHPI (N-hydrox
- Hu, Wei-Jie,Ji, Hong-Bing,Sun, Mu-Zhao,Zhou, Xian-Tai
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- Selective catalytic synthesis of bio-based terephthalic acid from lignocellulose biomass
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_Efficient synthesis of bio-based chemicals from renewable lignocellulosic biomass is of great significance to promote the sustainable development of chemical industry. This work aims to demonstrate that terephthalic acid, a bulk high value chemical in petrochemical industry, can be synthesized using biomass. This novel controllable transformation process was started with the selective catalytic pyrolysis of sawdust biomass to form p-xylene intermediate. The high p-xylene yield of 23.4% was obtained using the Ga2O3/SiO2/HZSM-5 catalyst under the optimized reaction condition. Subsequently, the selective oxidation of the biomass-derived aromatic intermediates to terephthalic acid was realized with the metal oxide catalysts. The highest terephthalic acid yield of 72.8% with the terephthalic acid selectivity of 82.3% was achieved using the CoMn2O4@SiO2@Fe3O4 catalyst. Based on the study of the catalytic conversion of the model compounds and the catalyst characterizations, the reaction pathways and possible reaction mechanism have been proposed.
- Fan, Minghui,He, Yuting,Li, Quanxin,Luo, Yuehui,Yang, Mingyu,Zhang, Yanhua,Zhu, Lijuan
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- Plasmonic O2dissociation and spillover expedite selective oxidation of primary C-H bonds
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Manipulating O2 activation via nanosynthetic chemistry is critical in many oxidation reactions central to environmental remediation and chemical synthesis. Based on a carefully designed plasmonic Ru/TiO2-x catalyst, we first report a room-temperature O2 d
- Jiang, Fuze,Li, Hao,Ruan, Qifeng,Shang, Huan,Wang, Jing,Zhang, Lizhi,Zhu, Xingzhong
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p. 15308 - 15317
(2021/12/13)
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- Chemoselective synthesis of imine and secondary amine from nitrobenzene and benzaldehyde by Ni3Sn2 alloy catalyst supported on TiO2
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Ni3Sn2/TiO2 alloy catalyst prepared by hydrothermal method was applied for the direct one-pot reductive imination of benzaldehyde with nitrobenzene in the presence of H2 gas as a reducing agent. A desired imine, benzylideneaniline, was produced in an excellent yield of 90% without the formation of any by-products. This is due to the chemoselective molecular recognition of Ni3Sn2 alloy nanoparticles supported on TiO2 for the nitro group over the carbonyl group. By prolonging the reaction time, the desired imine was converted into the corresponding secondary amine, N-phenylbenzylamine, with a remarkably high yield of 80% through the catalytic hydrogenation of the C[dbnd]N bond. Finally, we demonstrated that it was easy to reuse the catalyst up to five times.
- Yamanaka, Nobutaka,Hara, Takayoshi,Ichikuni, Nobuyuki,Shimazu, Shogo
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- Designing of Highly Active and Sustainable Encapsulated Stabilized Palladium Nanoclusters as well as Real Exploitation for Catalytic Hydrogenation in Water
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Abstract: Encapsulated nanoclusters based on palladium, 12-tunstophosphoric acid and silica was designed by simple wet impregnation methodology. The catalyst was found to be very efficient towards cyclohexene hydrogenation up to five catalytic runs with substrate/catalyst ratio of 4377/1 at 50?°C as well as for alkene, aldehyde, nitro and halogen compounds. Graphic Abstract: Silica encapsulated Pd nanoclusters stabilized by 12-tungstophosphoric acid is proved to be sustainable and excellent for water mediated hydrogenation reaction with very high catalyst to substrate ratio as well as TON.[Figure not available: see fulltext.]
- Patel, Anish,Patel, Anjali
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p. 803 - 820
(2020/08/12)
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- A new and efficient methodology for olefin epoxidation catalyzed by supported cobalt nanoparticles
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A new heterogeneous catalytic system consisting of cobalt nanoparticles (CoNPs) supported on MgO and tert-butyl hydroperoxide (TBHP) as oxidant is presented. This CoNPs@MgO/t-BuOOH catalytic combination allowed the epoxidation of a variety of olefins with good to excellent yield and high selectivity. The catalyst preparation is simple and straightforward from commercially available starting materials and it could be recovered and reused maintaining its unaltered high activity.
- Rossi-Fernández, Lucía,Dorn, Viviana,Radivoy, Gabriel
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p. 519 - 526
(2021/03/31)
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- Indirect reduction of CO2and recycling of polymers by manganese-catalyzed transfer hydrogenation of amides, carbamates, urea derivatives, and polyurethanes
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The reduction of polar bonds, in particular carbonyl groups, is of fundamental importance in organic chemistry and biology. Herein, we report a manganese pincer complex as a versatile catalyst for the transfer hydrogenation of amides, carbamates, urea derivatives, and even polyurethanes leading to the corresponding alcohols, amines, and methanol as products. Since these compound classes can be prepared using CO2as a C1 building block the reported reaction represents an approach to the indirect reduction of CO2. Notably, these are the first examples on the reduction of carbamates and urea derivatives as well as on the C-N bond cleavage in amides by transfer hydrogenation. The general applicability of this methodology is highlighted by the successful reduction of 12 urea derivatives, 26 carbamates and 11 amides. The corresponding amines, alcohols and methanol were obtained in good to excellent yields up to 97%. Furthermore, polyurethanes were successfully converted which represents a viable strategy towards a circular economy. Based on control experiments and the observed intermediates a feasible mechanism is proposed.
- Liu, Xin,Werner, Thomas
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p. 10590 - 10597
(2021/08/20)
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- Direct Heterogenization of the Ru-Macho Catalyst for the Chemoselective Hydrogenation of α,β-Unsaturated Carbonyl Compounds
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In this study, a commercially available homogeneous pincer-type complex, Ru-Macho, was directly heterogenized via the Lewis acid-catalyzed Friedel-Crafts reaction using dichloromethane as the cross-linker to obtain a heterogeneous, pincer-type Ru porous organometallic polymer (Ru-Macho-POMP) with a high surface area. Notably, Ru-Macho-POMP was demonstrated to be an efficient heterogeneous catalyst for the chemoselective hydrogenation of α,β-unsaturated carbonyl compounds to their corresponding allylic alcohols using cinnamaldehyde as a model compound. The Ru-Macho-POMP catalyst showed a high turnover frequency (TOF = 920 h-1) and a high turnover number (TON = 2750), with high chemoselectivity (99%) and recyclability during the selective hydrogenation of α,β-unsaturated carbonyl compounds.
- Padmanaban, Sudakar,Gunasekar, Gunniya Hariyanandam,Yoon, Sungho
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supporting information
p. 6881 - 6888
(2021/03/01)
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