- A novel redox system for the palladium(II)-catalyzed oxidation based on redox of polyanilines
-
A complex system consisting of palladium(II) acetate and polyaniline derivatives permitted the catalytic Wacker oxidation, indicating that polyanilines serve as a ligand with reversible redox capability under oxygen atmosphere. Substitution on the phenyl ring and protonic acid doping of polyanilines were found to affect the catalytic activity.
- Hirao, Toshikazu,Higuchi, Masayoshi,Hatano, Bunpei,Ikeda, Isao
-
-
Read Online
- Recyclable catalyst reservoir: Oxidation of alcohols mediated by noncovalently supported bis(imidazolium)-tagged 2,2,6,6-tetramethylpiperidine 1-oxyl
-
Bis(imidazolium)-tagged 2,2,6,6-tetramethylpiperidine 1-oxyl (TEMPO) catalysts were adsorbed on different supports such as silica gel, silica gel modified with highly cross-linked polymeric imidazolium networks, and highly cross-linked polymeric imidazolium networks entrapping magnetic particles. These systems provided a convenient tool for the oxidation of both primary and secondary alcohols working as recyclable reservoirs for the bis(imidazolium)-tagged TEMPO catalysts. By using EPR spectroscopy it was demonstrated that the catalyst was released as the corresponding oxoammonium salt in the solution during the recycling step, thus promoting the oxidative process in a homogeneous fashion. After solvent removal, the catalyst was readsorbed on the support allowing an easy recovery and recycle of the catalytic material up to 13 consecutive cycles with no loss in activity. The bis(imidazolium)-tagged TEMPO catalyst could be used in only 1mol% both for the oxidation of benzylic and aliphatic alcohols. The catalytic material was highly recyclable if used on silica or imidazolium-modified silica gel in 10mol% loading. Loading could be scaled down to 1mol% and the catalyst proved to be recyclable up to 8cycles only with imidazolium-modified silica gel. Such a "catalyst-sponge-like" system permits to combine the benefits of homogeneous and heterogeneous catalysis. Catch and release: Why spend money on covalent immobilization or ionic liquids with bulky cations? A bis(imidazolium)-modified 2,2,6,6-tetramethylpiperidine 1-oxyl catalyst can be adsorbed on an imidazolium-modified support, then released in the presence of a proper organic solvent and recaptured at the end of the reaction on removal of the solvent.
- Beejapur, Hazi Ahmad,Giacalone, Francesco,Noto, Renato,Franchi, Paola,Lucarini, Marco,Gruttadauria, Michelangelo
-
-
Read Online
- Palladium-copper-DMF complexes involved in the oxidation of alkenes
-
Treatment of PdCl2(MeCN)2 and CuCl with N,N-dimethylformamide (DMF) under O2 gives polymeric complex [(PdCl2)2CuCl2(DMF)4]n (1) and Pd-Cu heterometallic complex 2 containing O atom derived from molecular oxygen.
- Hosokawa, Takahiro,Nomura, Toshihiro,Murahashi, Shun-Ichi
-
-
Read Online
- V2O5@TiO2 Catalyzed Green and Selective Oxidation of Alcohols, Alkylbenzenes and Styrenes to Carbonyls
-
The versatile application of different functional groups such as alcohols (1° and 2°), alkyl arenes, and (aryl)olefins to construct carbon-oxygen bond via oxidation is an area of intense research. Here, we report a reusable heterogeneous V2O5@TiO2 catalyzed selective oxidation of various functionalities utilizing different mild and eco-compatible oxidants under greener reaction conditions. The method was successfully applied for the alcohol oxidation, oxidative scission of styrenes, and benzylic C?H oxidation to their corresponding aldehydes and ketones. The utilization of mild and eco-friendly oxidizing reagents such as K2S2O8, H2O2 (30 % aq.), TBHP (70 % aq.), broad substrate scope, gram-scale synthesis, and catalyst recyclability are notable features of the developed protocol.
- Upadhyay, Rahul,Kumar, Shashi,Maurya, Sushil K.
-
p. 3594 - 3600
(2021/07/02)
-
- Bismuth subnitrate-catalyzed markovnikov-type alkyne hydrations under batch and continuous flow conditions
-
Bismuth subnitrate is reported herein as a simple and efficient catalyst for the atom-economical synthesis of methyl ketones via Markovnikov-type alkyne hydration. Besides an effective batch process under reasonably mild conditions, a chemically intensified continuous flow protocol was also developed in a packed-bed system. The applicability of the methodologies was demonstrated through hydration of a diverse set of terminal acetylenes. By simply switching the reaction medium from methanol to methanol-d4, valuable trideuteromethyl ketones were also prepared. Due to the ready availability and nontoxicity of the heterogeneous catalyst, which eliminated the need for any special additives and/or harmful reagents, the presented processes display significant advances in terms of practicality and sustainability.
- ?tv?s, Sándor B.,Fül?p, Ferenc,Szécsényi, Zsanett
-
-
- Structural elucidation of a methylenation reagent of esters: Synthesis and reactivity of a dinuclear titanium(iii) methylene complex
-
Transmetallation of a zinc methylene complex [ZnI(tmeda)]2(μ-CH2) with a titanium(iii) chloride [TiCl3(tmeda)(thf)] produced a titanium methylene complex. The X-ray diffraction study displayed a dinuclear methylene structure [TiCl(tmeda)]2(μ-CH2)(μ-Cl)2. Treatment of an ester with the titanium methylene complex resulted in methylenation of the ester carbonyl to form a vinyl ether. The titanium methylene complex also reacted with a terminal olefin, resulting in olefin-metathesis and olefin-homologation. Cyclopropanation by methylene transfer from the titanium methylene proceeded by use of a 1,3-diene. The mechanistic study of the cyclopropanation reaction by the density functional theory calculations was also reported.
- Kurogi, Takashi,Kuroki, Kaito,Moritani, Shunsuke,Takai, Kazuhiko
-
p. 3509 - 3515
(2021/03/29)
-
- MnO2as a terminal oxidant in Wacker oxidation of homoallyl alcohols and terminal olefins
-
Efficient and mild reaction conditions for Wacker-type oxidation of terminal olefins of less explored homoallyl alcohols to β-hydroxy-methyl ketones have been developed by using a Pd(ii) catalyst and MnO2 as a co-oxidant. The method involves mild reaction conditions and shows good functional group compatibility along with high regio- and chemoselectivity. While our earlier system of PdCl2/CrO3/HCl produced α,β-unsaturated ketones from homoallyl alcohols, the present method provided orthogonally the β-hydroxy-methyl ketones. No overoxidation or elimination of benzylic and/or β-hydroxy groups was observed. The method could be extended to the oxidation of simple terminal olefins as well, to methyl ketones, displaying its versatility. An application to the regioselective synthesis of gingerol is demonstrated.
- Fernandes, Rodney A.,Ramakrishna, Gujjula V.,Bethi, Venkati
-
p. 6115 - 6125
(2020/10/27)
-
- Tuning Flavin-Based Photocatalytic Systems for Application in the Mild Chemoselective Aerobic Oxidation of Benzylic Substrates
-
New flavin-based photocatalytic systems used for chemoselective aerobic visible-light oxidations have been developed by tuning the flavin structure and reaction conditions. 1,3-Dimethyl-7-trifluoromethylalloxazine (2) and 10-butyl-3-methyl-7-trifluoromethylisoalloxazine (3) were shown to mediate the selective oxidation of benzyl alcohols to form aldehydes in the presence of Cs2CO3. Flavin 3 was superior in the oxidation of toluene derivatives to form aldehydes in the presence of trifluoroacetic acid. On the other hand, photooxidations provided by ethylene-bridged quaternary flavinium salt 1 gave the corresponding carboxylic acids. The usefulness of the developed catalytic systems using 1–3 was also demonstrated in the oxidation of secondary benzylic and aliphatic alcohols, and benzylic methylene groups to form the corresponding ketones. The systems have the advantage of a broad substrate scope and metal-free conditions, which distinguish them from the previously reported flavin photooxidation reactions.
- Tolba, Amal Hassan,Vávra, Franti?ek,Chudoba, Josef,Cibulka, Radek
-
supporting information
p. 1579 - 1585
(2019/12/24)
-
- Hydration of terminal alkynes catalyzed by cobalt corrole complex
-
Cobalt(III) corrole was firstly applied to the hydration of terminal alkynes. The alkyne hydration proceeded in good to excellent yield with 0.03 to 0.3 mol% cobalt corrole catalyst loading. A wide range of substrates were tolerated. Particularly, the reaction can give 90% yield in a gram scale experiment.
- Lai, Jia-Wei,Liu, Zhao-Yang,Chen, Xiao-Yan,Zhang, Hao,Liu, Hai-Yang
-
supporting information
(2020/10/02)
-
- Selective Visible Light Aerobic Photocatalytic Oxygenation of Alkanes to the Corresponding Carbonyl Compounds
-
The aerobic, selective oxygenation of alkanes via C-H bond activation is an important research challenge. Photocatalysis offers the potential for the introduction of additional concepts for such reactions. Visible light photoactive semiconductors such as bismuth oxyhalides (BiOX, X = Cl and Br) used in this research typically oxidize organic compounds through photocatalyzed formation of strongly oxidizing holes. The reactive oxygen species formed react with organic compounds in one-electron processes, leading to radical intermediates and nonselective oxidation. Such oxidation reactions generally lead to total oxidation. Here, impregnation of BiOX with a polyoxometalate, H5PV2Mo10O40, as a strong electron acceptor changed the reactivity of BiOX, leading to Mars-van Krevelen-type reactivity, that is, photoactivated oxygen donation from BiOX to the organic substrate followed by reoxidation by O2 and catalysis. This conclusion was supported by mechanistic studies involving isotope labeling studies. In this way, ethane was selectively oxidized to acetaldehyde in a flow reactor with a turnover number (24 h) of 415.
- Somekh, Miriam,Khenkin, Alexander M.,Herman, Adi,Neumann, Ronny
-
p. 8819 - 8824
(2019/09/30)
-
- Enhancing the photo-efficacy of an organic visible-light-activated chromophore (alizarin red S) on zinc oxide with a Ag-Na electrolyte to photo-transform aromatic and aliphatic alcohols
-
The development of an aqueous silver-sodium/alizarin red sensitised zinc oxide system has been reported to oxidise a range of both aromatic and aliphatic alcohols to aldehydes. Furthermore, photoluminescence spectroscopy validated the electron quenching effect of zinc oxide's defect sites after surface sensitising the metal-oxide with alizarin red. Powder diffuse reflectance UV/Vis data further substantiated the visible-light attenuated properties of alizarin red sensitised zinc oxide, and hence justification for its visible light reactivity towards alcohol oxidations. Lastly, density functional theory calculations supported the intermolecular photo-electronic transfer between alizarin red organic and zinc oxide.
- Underwood, Timothy M.,Robinson, Ross S.
-
p. 24259 - 24266
(2019/08/15)
-
- Balancing Bulkiness in Gold(I) Phosphino-triazole Catalysis
-
The syntheses of a series of 1-phenyl-5-phosphino 1,2,3-triazoles are disclosed, within which, the phosphorus atom (at the 5-position of a triazole) is appended by one, two or three triazole motifs, and the valency of the phosphorus(III) atom is completed by two, one or zero ancillary (phenyl or cyclohexyl) groups respectively. This series of phosphines was compared with tricyclohexylphosphine and triphenylphosphine to study the effect of increasing the number of triazoles appended to the central phosphorus atom from zero to three triazoles. Gold(I) chloride complexes of the synthesised ligands were prepared and analysed by techniques including single-crystal X-ray diffraction structure determination. Gold(I) complexes were also prepared from 1-(2,6-dimethoxy)-phenyl-5-dicyclohexyl-phosphino 1,2,3-triazole and 1-(2,6-dimethoxy)-phenyl-5-diphenyl-phosphino 1,2,3-triazole ligands. The crystal structures thus obtained were examined using the SambVca (2.0) web tool and percentage buried volumes determined. The effectiveness of these gold(I) chloride complexes to serve as precatalysts for alkyne hydration were assessed. Furthermore, the regioselectivity of hydration of but-1-yne-1,4-diyldibenzene was probed.
- Zhao, Yiming,Wakeling, Matthew G.,Meloni, Fernanda,Sum, Tze Jing,van Nguyen, Huy,Buckley, Benjamin R.,Davies, Paul W.,Fossey, John S.
-
p. 5540 - 5548
(2019/08/07)
-
- Chemoselective Hydrogenation of α,β-Unsaturated Carbonyls Catalyzed by Biomass-Derived Cobalt Nanoparticles in Water
-
Herein, we report highly chemoselective hydrogenation of α,β-unsaturated carbonyls to saturated carbonyls catalyzed by cobalt nanoparticles supported on the biomass-derived carbon from bamboo shoots with molecular hydrogen in water, which is the first prototype using a heterogeneous non-noble metal catalyst for such organic transformation as far as we know. The optimal cobalt nanocatalyst, CoOx@NC-800, manifested remarkable activity and selectivity for hydrogenation of C=C in α,β-unsaturated carbonyls under mild conditions. A broad set of α,β-aromatic and aliphatic unsaturated carbonyls were selectively reduced to their corresponding saturated carbonyls in up to 99 % yields with good tolerance of various functional groups. Meanwhile, a new straightforward one-pot cascade synthesis of saturated carbonyls was realized with high activity and selectivity via the cross-aldol condensation of ketones with aldehydes followed by selective hydrogenation. More importantly, this one-pot strategy is applicable for the expedient synthesis of Loureirin A, a versatile bioactive and medicinal molecule, from readily available starting materials, further highlighting the practical utility of the catalyst. In addition, the catalyst can be easily separated for successive reuses without significant loss in both activity and selectivity.
- Song, Tao,Ma, Zhiming,Yang, Yong
-
p. 1313 - 1319
(2019/01/25)
-
- Synthesis of mesoporous ZSM-5 zeolites and catalytic cracking of ethanol and oleic acid into light olefins
-
Conversion of biomass-derived chemicals into light olefins is a promising method to maintain sustainable development of light olefin industry. In this study, three mesoporous ZSM-5 zeolites (MZSM-5-A, MZSM-5-B and MZSM-5-C) with major pore diameter about 4.8 nm, 16 nm and 22 nm were synthesized using a hydrothermal method by utilizing different templates. The catalytic activity of catalysts was studied by catalytic cracking of ethanol and oleic acid. The influence of reaction temperature on conversion and product selectivity was investigated. The characterization of ZSM-5 samples showed that the orders of the external surface area and mesopore volume were MZSM-5-C > MZSM-5-B > MZSM-5-A > conventional HZSM-5. In ethanol to light olefin reaction, MZSM-5-C achieved the highest light olefin yield (318.3 mL g?1) and ethylene selectivity (42.3%) at 400 °C. In oleic acid to light olefin reaction, MZSM-5-B achieved a complete conversion of oleic acid at 500 °C, and obtained the highest light olefin selectivity (38.1%) at 550 °C. The difference may be relevant to the size and chemical structure of feedstock molecular as well as the acidity of catalysts. Regardless of ethanol or oleic acid as feedstock, introduction of mesopore in zeolites significantly enhanced the light olefin yield and selectivity.
- Zhao, Tingting,Li, Fuwei,Yu, Hongchang,Ding, Shilei,Li, Zhixia,Huang, Xinyuan,Li, Xiang,Wei, Xiaohan,Wang, Zhenlin,Lin, Hongfei
-
p. 101 - 110
(2019/02/24)
-
- Synthesis, structural characterization and C–H activation property of a tetra-iron(III) cluster
-
A non-heme tetra-iron cluster, [Fe4 III(μ-O)2(μ-OAc)6(2,2′-bpy)2(H2O)2](NO3 ?)(OH?) (1), [OAc = acetate; 2,2′-bpy = 2,2′-bipyridine] containing oxido- and acetato-bridges was synthesized and structurally characterized by different spectroscopic methods including single crystal X-ray diffraction studies. X-ray crystal structure analysis of 1 revealed that tetra-iron complex was crystallized in monoclinic system with C2/c space group. Each of the Fe centres in 1 was found to exist in octahedral geometry and interconnected by oxido- and acetato-bridges. Bond valence sum (BVS) calculation recommended the existence of iron centres in +3 oxidation state. Variable temperature magnetic measurement authenticated the dominating antiferromagnetic ordering among the iron centres in the solid state of 1. This tetra-iron cluster was also evaluated as an efficient catalytic system towards the oxidation of both linear & cyclic alkanes without production of primary C–H bond oxidation products. Oxidation of secondary C–H bonds attested the formation of both the corresponding alcohols & ketones in 27–900 TONs. The tetra-iron catalytic system with Alcohol/Ketone values 0.2–1.7 indicated the involvement of freely diffusing carbon-centered radicals rather than metal based oxidant.
- Dey, Dhananjay,Patra, Moumita,Al-Hunaiti, Afnan,Yadav, Hare Ram,Al-mherat, Afrah,Arar, Sharif,Maji, Milan,Choudhury, Angshuman Roy,Biswas, Bhaskar
-
p. 220 - 226
(2019/01/05)
-
- Hydrofunctionalization of olefins to value-added chemicals: Via photocatalytic coupling
-
A green strategy was developed for the synthesis of various value-added chemicals using methanol, acetonitrile, acetic acid, acetone and ethyl acetate as the hydrogen source by coupling them with olefins over heterogeneous photocatalysts. A radical coupling mechanism was proposed for the hydrofunctionalization of olefins with methanol to higher aliphatic alcohols over the Pt/TiO2 catalyst as the model reaction. C-H bond cleavage and C-C bond formation between photogenerated radicals and terminal olefins were accomplished in a single reaction at high efficiency. Our approach is atomically economical with high anti-Markovnikov regioselectivity and promising application potential under mild reaction conditions.
- Fan, Yonghui,Li, Shenggang,Bao, Jingxian,Shi, Lei,Yang, Yanzhang,Yu, Fei,Gao, Peng,Wang, Hui,Zhong, Liangshu,Sun, Yuhan
-
supporting information
p. 3450 - 3456
(2018/08/06)
-
- Metal-Free catalyst for visible-light-induced oxidation of unactivated alcohols using Air/Oxygen as an oxidant
-
9-Fluorenone acts as a metal-free and additive-free photocatalyst for the selective oxidation of primary and secondary alcohols under visible light. With this photocatalyst, a plethora of alcohols such as aliphatic, heteroaromatic, aromatic, and alicyclic compounds has been converted to the corresponding carbonyl compounds using air/oxygen as an oxidant. In addition to these, several steroids have been oxidized to the corresponding carbonyl compounds. Detailed mechanistic studies have also been achieved to determine the role of the oxidant and the photocatalyst for this oxidation.
- Schilling, Waldemar,Riemer, Daniel,Zhang, Yu,Hatami, Nareh,Das, Shoubhik
-
p. 5425 - 5430
(2018/05/15)
-
- Highly practical and efficient preparation of aldehydes and ketones from aerobic oxidation of alcohols with an inorganic-ligand supported iodine catalyst
-
Herein, we divulge an efficient protocol for aerobic oxidation of alcohols with an inorganic-ligand supported iodine catalyst, (NH4)5[IMo6O24]. The catalyst system is compatible with a wide range of groups and exhibits high selectivity, and shows excellent stability and reusability, thus serving as a potentially greener alternative to the classical transformations.
- Zhang, Mengqi,Zhai, Yongyan,Ru, Shi,Zang, Dejin,Han, Sheng,Yu, Han,Wei, Yongge
-
supporting information
p. 10164 - 10167
(2018/09/13)
-
- The gold-catalyzed formal hydration, decarboxylation, and [4+2] cycloaddition of alkyne derivatives featuring L2/Z-type diphosphinoborane ligands
-
The catalytic formal hydration of alkynes and decarbox-ylation of alkynoic acid were developed using a Au catalyst featuring a Z-ligand. Furthermore, the intramolecular [4+2] cycloaddition of the alkynoic acid-alkene derivative for the formation of the oxabicyclo[4.4.0] skeleton also proceeded.
- Matsumoto, Chiaki,Yamada, Masayuki,Dong, Xun,Mukai, Chisato,Inagaki, Fuyuhiko
-
p. 1321 - 1323
(2018/10/15)
-
- Copper based coordination polymers based on metalloligands: Utilization as heterogeneous oxidation catalysts
-
This work presents the synthesis and characterization of two Cu(ii)-based coordination polymers prepared by utilizing two different Co(iii)-based metalloligands offering appended arylcarboxylic acid groups. Both coordination polymers are three-dimensional in nature and present pores and channels filled with water molecules. Both coordination polymers function as heterogeneous catalysts for the epoxidation of various olefins using O2 while employing isobutyraldehyde as the coreductor and for peroxide-mediated oxidation of assorted benzyl alcohols. The catalytic results illustrate efficient oxidation reactions, whereas the hot-fltration test and leaching experiments indicate the true heterogeneous nature of the catalysis.
- Kumar, Gulshan,Hussain, Firasat,Gupta, Rajeev
-
p. 16985 - 16994
(2019/01/03)
-
- Wacker Oxidation of Terminal Alkenes Over ZrO2-Supported Pd Nanoparticles Under Acid- and Cocatalyst-Free Conditions
-
Highly efficient Wacker oxidation of aromatic or aliphatic terminal alkenes into methyl ketones and benzofurans is developed by using reusable Pd0 nanoparticles (NPs) supported on ZrO2 under acid- and cocatalyst-free conditions. Molecular oxygen or air can be utilized as the terminal oxidant, which results in the formation of H2O as the only theoretical byproduct. The activation of the Pd NPs by O2 plays an important role in promoting this reaction. Interestingly, PdO supported on ZrO2 showed no activity. Additionally, the Pd particle size significantly affects the catalytic activity, with an apparent optimal diameter of 4–12 nm. In addition to the heterogeneous catalyst forms, the Pd NPs can be generated from a Pd0 complex during the reaction, and these particles are even recyclable.
- Zhang, Zhenzhong,Kumamoto, Yuhya,Hashiguchi, Taishin,Mamba, Tetsuya,Murayama, Haruno,Yamamoto, Eiji,Ishida, Tamao,Honma, Tetsuo,Tokunaga, Makoto
-
p. 3482 - 3489
(2017/09/15)
-
- POLYMER-SUPPORTED TRANSITION CATALYST
-
A long life catalyst is provided that is conveniently and inexpensively capable of being produced and that is highly active and has inhibited metal leakage. According to aspects of the present invention, a catalyst is provided that includes: a polymer including a plurality of first structural units and a plurality of second structural units; and metal acting as a catalytic center, wherein at least part of the metal is covered with the polymer, each of the plurality of first structural units has a first atom constituting a main chain of the polymer and a first substituent group bonded to the first atom, a second atom included in each of the plurality of second structural units is bonded to the first atom, and the second atom is different from the first atom, or at least one of all substituent groups on the second atom is different from the first substituent group.
- -
-
Paragraph 0227
(2017/10/18)
-
- 5-Nitroso-1,3-diphenyltetrazolium salt as a mediator for the oxidation of alcohols
-
We describe the synthesis of a mesoion-derived nitroso compound, 5-nitroso-1,3-diphenyltetrazolium tetrafluoroborate (1), and its application in the oxidation of alcohols. The structure of 1 was fully characterized by X-ray analysis, showing that it exists as a monomer in the solid state. In the cyclic voltammetric analysis of 1, a reversible redox peak was observed at 0.43 V (vs. Ag/Ag+ in MeCN) under acidic conditions. It was subsequently shown that the nitrosotetrazolium salt 1 is capable of stoichiometrically oxidizing alcohols to the corresponding carbonyl compounds effectively. This nitroso heterocycle and its reduced form, i.e., the corresponding mesoionic hydroxyamide, participate in a redox cycle involving the catalytic oxidation of alcohols by the aid of HNO3 under mild conditions.
- Matsukawa, Yuta,Hirashita, Tsunehisa,Araki, Shuki
-
p. 6052 - 6056
(2017/09/23)
-
- A simple route to 1,4-addition reactions by Co-catalyzed reductive coupling of organic tosylates and triflates with activated alkenes
-
An efficient Co-catalyzed 1,4-addition reaction of alkyl/aryl triflates and tosylates with activated alkenes is described. In this reaction, an air-stable cobalt(ii) complex, a mild reducing agent Zn and a simple proton source (H2O) are used. A radical mechanism for the addition of alkyl tosylates to activated alkenes is likely involved.
- Hsieh, Jen-Chieh,Chu, Yi-Hua,Muralirajan, Krishnamoorthy,Cheng, Chien-Hong
-
p. 11584 - 11587
(2017/10/27)
-
- Hypervalent Iodine as a Terminal Oxidant in Wacker-Type Oxidation of Terminal Olefins to Methyl Ketones
-
A mimic of the Wacker process for C=O bond formation in terminal olefins can be initiated by a combination of the Pd(II) and hypervalent iodine reagent, Dess-Martin periodinane to generate methyl ketones. This operationally simple and scalable method offers Markovnikov selectivity, has good functional group compatibility, and is mild and high yielding.
- Chaudhari, Dipali A.,Fernandes, Rodney A.
-
p. 2113 - 2121
(2016/03/15)
-
- A functionalized phosphine merit preparation of ionic liquids and its application in the hydroformylation reaction
-
The invention relates to synthesis of first-class phosphorus functionalized polyether alkyl guanidinium ionic liquid, and an application of the first-class phosphorus functionalized polyether alkyl guanidinium ionic liquid in a homogeneous catalytic reaction. The functionalized ionic liquid of such class can be easily prepared by an ion exchange reaction between the polyether alkyl guanidinium ionic liquid and sulfonic acid type water soluble phosphine ligand. The designed phosphorus functionalized ionic liquid can be applied to organic reactions, including hydroformylation, hydroesterification, hydrocarboxylation and catalytic hydrogenation under the catalyzing of a transition metal; the dosage of the ionic liquid used in the catalytic reaction can be decreased; the activity of the catalytic reaction can be improved; a catalyst can be separated and cycled simply and conveniently.
- -
-
Paragraph 0071; 0072; 0073
(2017/11/08)
-
- Alcohol oxidation via recyclable hydrophobic ionic liquid-supported IBX
-
The first ionic hydrophobic liquid-supported 1-hydroxy-1,2-benziodoxole-3(1H)-one-1-oxide (IBX) reagent was prepared for oxidizing alcohols. In this study, a hydrophobic ionic liquid-supported IBX reagent was synthesized and described. This hydrophobic ionic liquid-supported IBX reagent was able to be recovered and used in a recyclable reaction system by re-oxidation and washing.
- Koguchi, Shinichi,Mihoya, Aya,Mimura, Minato
-
p. 7633 - 7637
(2016/11/11)
-
- Alcohol oxidation with H2O2 catalyzed by a cheap and promptly available imine based iron complex
-
We previously reported that the iminopyridine iron(II) complex 1, easily and quantitatively obtainable in situ, can activate H2O2 to form a powerful oxidant, capable of aliphatic C-H bond hydroxylation. In the present study we expand the application of this catalyst to the oxidation of a series of alcohols to the corresponding carbonyl compounds. The oxidation of aliphatic alcohols proceeds smoothly, while that of benzylic alcohols is shown to be challenging. Some collected pieces of evidence suggest a preference of the oxidizing species for the aromatic ring instead for the alcoholic moiety. The decrease of the electron density in the aromatic ring shifts the oxidation from the aromatic towards the alcoholic moiety. Quite surprisingly, preferential oxidation of cyclohexanol versus benzylic alcohol was achieved, showing unprecedented selectivity.
- Olivo, Giorgio,Giosia, Simone,Barbieri, Alessia,Lanzalunga, Osvaldo,Di Stefano, Stefano
-
p. 10630 - 10635
(2016/11/21)
-
- Internal Alkyne Regio- and Chemoselectivity using a Zwitterionic N-Heterocyclic Carbene Gold Catalyst in a Silver-Free Alkyne Hydration Reaction
-
An alkyne hydration of terminal and internal alkynes is reported using a zwitterionic N-heterocyclic carbene gold catalyst [(BNHC)Au(SMe2)] in the absence of silver and Br?nsted acid additives. The hydration demonstrates good regioselectivity in alkyne hydration and chemoselectivity for internal alkynes vs. terminal. In addition, (BNHC)Au(SMe2) performs a propargyl alcohol hydration to predominantly form α-hydroxymethyl ketone over the more common Meyer–Schuster rearrangement product. While complex (BNHC)Au(SMe2) is active without silver additives, addition of silver hexafluoroantimonate (AgSbF6) increases reaction rate and decreases selectivity for internal alkyne hydration over terminal substrates. To the best of our knowledge, the rate enhancement of (BNHC)Au(SMe2) by AgSbF6is the first such demonstration of a silver effect for a “halide-free” Au catalyst. (Figure presented.).
- Weerasiri, Kushan C.,Chen, Danmin,Wozniak, Derek I.,Dobereiner, Graham E.
-
p. 4106 - 4113
(2016/12/30)
-
- An environmentally benign hydration of alkynes catalyzed by gallic acid/tannic acid in water
-
A gallic acid catalyzed hydration strategy from alkynes under mild conditions has been developed. The catalyst system exhibits excellent activity, thus avoiding the use of any transition metal, strong acids or other toxic reagent as cocatalysts. Recycling experiments were conducted, and this procedure can be scaled up. Other tannins such as tannic acid can also be applied in this reaction which shows the potential utilization of natural feedstocks.
- Deng, Tao,Wang, Cheng-Zhang
-
p. 7029 - 7032
(2016/10/07)
-
- Metal-Free Markovnikov-Type Alkyne Hydration under Mild Conditions
-
A Markovnikov-type alkyne hydration protocol is presented using 20% CF3SO3H (TfOH) as the catalyst under unprecedented mild conditions applicable to various alkynes, including terminal arylalkynes, terminal nonfunctionalized aliphatic alkynes, and internal alkynes with excellent regioselectivity in good to excellent yields (average yields >85%). The reaction procedure operates under mild conditions (25-70°C), with broad functional group compatibility, and uses only slightly more than a stoichiometric amount of water in the absence of any transition metal. The success of this protocol hinges upon the utilization of trifluoroethanol as the solvent.
- Liu, Wenbo,Wang, Haining,Li, Chao-Jun
-
supporting information
p. 2184 - 2187
(2016/06/01)
-
- Highly Efficient Cooperative Catalysis by CoIII(Porphyrin) Pairs in Interpenetrating Metal–Organic Frameworks
-
A series of porous twofold interpenetrated In-CoIII(porphyrin) metal–organic frameworks (MOFs) were constructed by in situ metalation of porphyrin bridging ligands and used as efficient cooperative catalysts for the hydration of terminal alkynes. The twofold interpenetrating structure brings adjacent CoIII(porphyrins) in the two networks parallel to each other with a distance of about 8.8 ?, an ideal distance for the simultaneous activation of both substrates in alkyne hydration reactions. As a result, the In-CoIII(porphyrin) MOFs exhibit much higher (up to 38 times) catalytic activity than either homogeneous catalysts or MOF controls with isolated CoIII(porphyrin) centers, thus highlighting the potential application of MOFs in cooperative catalysis.
- Lin, Zekai,Zhang, Zhi-Ming,Chen, Yu-Sheng,Lin, Wenbin
-
supporting information
p. 13739 - 13743
(2016/10/26)
-
- A Hantzsch Amido Dihydropyridine as a Transfer Hydrogenation Reagent for α,β-Unsaturated Ketones
-
An improved synthesis of the bis-methylamido Hantzsch dihydropyridine is described. The Hantzsch amide is demonstrated to be an effective transfer hydrogenation reagent using α,β-unsaturated ketones as the test case. Unreacted Hantzsch amide and the bis-methylamidopyridine byproduct are effectively removed by extraction in contrast to the commonly used Hantzsch diethyl ester. Several examples are given with the reaction being more effective for conjugated aromatic substrates than for aliphatics.
- Van Arman, Scott A.,Zimmet, Austin J.,Murray, Ian E.
-
p. 3528 - 3532
(2016/05/24)
-
- Diastereoselective synthesis of tetrasubstituted propargylamines via hydroamination and metalation of 1-alkynes and their enantioselective conversion to trisubstituted chiral allenes
-
Reaction of cyclic secondary amines with 1-alkynes and copper(I) chloride at 110-120 °C gives the corresponding alkynylcopper complex, which adds to the iminium ion intermediate formed in situ by hydroamination of 1-alkynes to give the corresponding propargylamine derivatives in up to 94% yield and 99% regioselectivity. The diastereomerically pure chiral propargylamines were obtained in 23-89% yield using optically active 2-benzyl morpholine and N-methyl camphanyl piperazine. These chiral propargylamines are readily converted to the corresponding trisubstitued chiral allenes in 71-89% yields with up to 99% ee upon reaction with ZnBr2 at 120 °C. The results are discussed considering mechanisms involving diastereoselective addition of alkynylcopper complex formed in situ to iminium ions formed in situ regioselectively to produce the corresponding propargylamines, which in turn give the chiral allenes with very high enantioselectivity via an intramolecular 1,5-hydrogen shift in the presence of zinc bromide.
- Periasamy, Mariappan,Reddy, Polimera Obula,Satyanarayana, Iddum,Mohan, Lakavathu,Edukondalu, Athukuri
-
p. 987 - 999
(2016/02/18)
-
- From DNA to catalysis: A thymine-acetate ligated non-heme iron(III) catalyst for oxidative activation of aliphatic C-H bonds
-
A non-heme, iron(iii)/THA(thymine-1-acetate) catalyst together with H2O2 as an oxidant is efficient in oxidative C-H activation of alkanes. Although having a higher preference for tertiary C-H bonds, the catalyst also oxidizes aliphatic secondary C-H bonds into carbonyl compounds with good to excellent conversions. Based on the site selectivity of the catalyst and our mechanistic studies the reaction proceeds via an Fe-oxo species without long lived carbon centered radicals.
- Al-Hunaiti, Afnan,R?is?nen, Minn?,Repo, Timo
-
p. 2043 - 2046
(2016/02/05)
-
- Ligand Effects in the Gold Catalyzed Hydration of Alkynes
-
In the gold(I) (e. g. L-Au-OTf) catalyzed hydration of alkynes, the steric hindrance of ligands has a significant influence on the kinetics of the reaction, whereas their electronic effects are less influential. Very low loadings (ppm levels) of a gold catalyst containing a highly sterically hindered phosphine ligand (e. g. L4-Au-OTf) (L4=Me3(OMe)tBuXPhos) is able to catalyze the hydration of a wide range of alkyne substrates in good yields, at relatively low temperature.
- Ebule, Rene E.,Malhotra, Deepika,Hammond, Gerald B.,Xu, Bo
-
supporting information
p. 1478 - 1481
(2016/05/19)
-
- Selective oxidation of hydrocarbons under air using recoverable silver ferrite-graphene (AgFeO2-G) nanocomposite: A good catalyst for green chemistry
-
The selective oxidation of hydrocarbons is a main academic and industrial research challenge. A lot of researches have been done about this issue, but till now relatively little attention has been paid to graphene-complex oxide nanocomposites. Herein, we report our studies on a new catalyst. Silver ferrite-graphene (AgFeO2-G) as a separable nanocomposite from the reaction solution, was used as an effective oxidizing agent for the oxidation of various hydrocarbons (1- decene, cyclohexene, cis-cycloctene, cyclohexane, cyclooctane etc.) under mild conditions (55 °C, 8 h) with high conversion and selectivity using air, that is proper for 'green' chemistry. Metal or metal oxide nanoparticles assembled on graphene sheets revealed high electrocatalytic activity. Indeed, AgFeO2 with graphene due to low band gap and graphene oxide with large amounts of oxygen-containing groups, provide facility catalytic activity of catalyst-supported system. We also found that, with this catalyst, selective oxidation could be achieved without the need for the addition of solvent, which is appropriate in particular for 'green' chemistry. The catalysts showed little deactivation and maintained their conversion and selectivity levels duration of the measurements.
- Hosseini, Seyed Majid,Hosseini-Monfared, Hassan,Abbasi, Vahideh,Khoshroo, Mohammad Reza
-
-
- PROCESS FOR REDUCING THE OXYGEN CONTENT OF BIOMASS USING VANADIUM-BASED CATALYSTS
-
The present invention concerns a process for converting biomass into useful organic building blocks for the chemical industry. The process involves the use of vanadium-based catalysts of the formula Aα+a(VvXxR1yR2z)α*a-, which may be readily prepared from industrial vanadium compounds, for converting a polyol in a solvent.
- -
-
Page/Page column 16; 17
(2016/07/27)
-
- Cationic palladium(II) complexes as catalysts for the oxidation of terminal olefins to methyl ketones using hydrogen peroxide
-
Ligated Pd(II) complexes have been studied for the catalytic oxidation of terminal olefins to their corresponding methyl ketones. The method uses aqueous hydrogen peroxide as the terminal oxidant; a sustainable and readily accessible oxidant. The choice of ligand, counterion and solvent all have a significant effect on catalytic performance and we were able to develop systems which perform well for these challenging oxidations.
- Cao, Qun,Bailie, David S.,Fu, Runzhong,Muldoon, Mark J.
-
supporting information
p. 2750 - 2757
(2015/05/27)
-
- Catalytic synergism in a C;inf;60;/inf;IL;inf;10;/inf;TEMPO;inf;2;/inf; hybrid in the efficient oxidation of alcohols
-
A novel fullerene [5:1]hexakisadduct bearing two 2,2,6,6-tetramethylpiperidine 1-oxyl (TEMPO) radicals and ten 1-propyl-3-methylimidazolium bromide moieties has been synthesized and characterized. Such an C;inf;60;/inf;IL;inf;10;/inf;TEMPO;inf;2;/inf; hybrid has been successfully employed as a catalyst in the selective oxidation of a wide series of alcohols and is highly active at just 0.1 mol% loading. Moreover, it can be easily recovered by adsorption onto a multilayered covalently-linked SILP phase (mlc-SILP) through a "release and catch" approach and reused for up to 12 cycles without loss in efficiency. Interestingly, a catalytic synergistic effect of TEMPO and imidazolium bromide moieties combined in the same hybrid has been clearly shown.
- Beejapur, Hazi Ahmad,Campisciano, Vincenzo,Giacalone, Francesco,Gruttadauria, Michelangelo
-
supporting information
p. 51 - 58
(2015/01/30)
-
- Aerobic flow oxidation of alcohols in water catalyzed by platinum nanoparticles dispersed in an amphiphilic polymer
-
We have developed a technique for the aqueous aerobic flow oxidation of alcohols in a continuous-flow reactor containing platinum nanoparticles dispersed on an amphiphilic polystyrene-poly(ethylene glycol) resin (ARP-Pt). Various primary and secondary alcohols including aliphatic, aromatic and heteroaromatic alcohols were efficiently oxidized within 73 seconds in a flowing aqueous system at 100-120°C under 40-70 bar of the system pressure to give the corresponding carboxylic acids and ketones, respectively, in up to 99% yield. Benzaldehydes could be also prepared selectively from benzyl alcohols by conducting the flow oxidation under the standard conditions in the presence of triethylamine. Moreover, a practical gram-scale synthesis of surfactants was realized in the aqueous aerobic continuous flow oxidation for 36-116 hours. This aerobic flow oxidation system provides a safe, clean, green, rapid and efficient practical method for oxidizing alcohols.
- Osako, Takao,Torii, Kaoru,Uozumi, Yasuhiro
-
p. 2647 - 2654
(2015/02/05)
-
- A simple procedure for the oxidation of alcohols using [bis(acetoxy)iodo]benzene and a catalytic amount of bromide ions in ethyl acetate
-
Abstract Primary and secondary benzylic alcohols and secondary aliphatic alcohols were oxidized to the corresponding aldehydes and ketones by using [bis(acetoxy)iodo]benzene (BAIB) and a catalytic amount of bromide ions, from tetrabutylammonium bromide or KBr, in ethyl acetate. The catalytic role of the bromide ions was also highlighted in the oxidation of primary aliphatic alcohols and secondary allylic alcohols carried out in the presence of 1 mol% TEMPO.
- Salvo, Anna Maria Pia,Campisciano, Vincenzo,Beejapur, Hazi Ahmad,Giacalone, Francesco,Gruttadauria, Michelangelo
-
p. 1179 - 1184
(2015/06/02)
-
- Hydration of alkynes at room temperature catalyzed by gold(I) isocyanide compounds
-
An effective method using gold(I) isocyanide complexes as catalysts for the transformation of various alkynes to the corresponding ketones is successfully developed. The hydration process proceeds smoothly at room temperature with quite high yield (up to 99%). The catalytic center is the isocyanide-Au(I)+ cation. Further theoretical research reveals a direct hydration mechanism by H2O, and the rate-determining step has an energy barrier of 23.7 kcal mol?1. These results show a good example to reduce unnecessary steps and achieve milder reaction conditions at the same time for the hydration of alkynes.
- Xu, Yun,Hu, Xingbang,Shao, Jing,Yang, Guoqiang,Wu, Youting,Zhang, Zhibing
-
supporting information
p. 532 - 537
(2018/04/16)
-
- Solvent-free hydration of alkynes over Hβ zeolite
-
Abstract An efficient and environmentally benign catalytic system has been successfully developed for highly Markovnikov selective hydration of various alkynes over heterogeneous catalyst (Hβ zeolite) in solvent-free conditions. The catalyst (Hβ zeolite) is commercial available, recyclable and exhibits excellent catalytic activity towards the hydration of alkynes to ketones. Moreover, the propargylic aryl carbinols undergo Meyer-Schuster rearrangement to give α,β-unsaturated carbonyl compounds in excellent yields.
- Mameda, Naresh,Peraka, Swamy,Marri, Mahender Reddy,Kodumuri, Srujana,Chevella, Durgaiah,Gutta, Naresh,Nama, Narender
-
p. 213 - 216
(2015/08/24)
-
- Silver-containing microemulsion as a high-efficient and recyclable catalytic system for hydration of alkynes
-
A silver-catalyzed highly efficient and regioselective synthesis of ketones from a wide range of alkynes is described. The reaction is dramatically accelerated by its performance in aqueous emulsion, which is self-assembled by the addition of silver perfluorooctanesulfonate (1) and perfluorooctanesulfonic acid (PFOS) to water. The reaction is conducted under convenient conditions with broad substrate scope, including a variety of aromatic and aliphatic terminal alkynes and internal alkynes. Furthermore, the air- and light-stable silver catalytic microemulsion can be reused for 4 times with minimal change in catalytic efficiency.
- Dong, Qizhi,Li, Ningbo,Qiu, Renhua,Wang, Jinying,Guo, Cancheng,Xu, Xinhua
-
p. 122 - 127
(2015/10/12)
-
- Visible light promoted hydration of alkynes catalyzed by rhodium(III) porphyrins
-
Visible light promoted hydration of a wide scope of alkynes to ketones catalyzed by rhodium(iii) porphyrin complexes was described. The key intermediate β-carbonyl alkyl was observed and independently synthesized. The rate of photolysis is over two orders of magnitude faster than that of the thermal process.
- Liu, Xu,Liu, Lianghui,Wang, Zikuan,Fu, Xuefeng
-
supporting information
p. 11896 - 11898
(2015/07/20)
-
- 1H-pyrrole-2,4-dicarbonyl-derivatives and their use as flavoring agents
-
The present invention primarily relates to 1H-pyrrole-2,4-dicarbonyl-derivatives of Formula (I) wherein R1, R2, R3, Z. Z' and J are as defined in the description, to mixtures thereof and to the use thereof as flavoring agents. The compounds in accordance with the present invention are suitable for producing, imparting, or intensifying an umami flavor. The invention further relates to flavoring mixtures, compositions for oral consumption as well as ready-to-eat, ready-to-use and semifinished products, comprising an effective amount of the compound of Formula (I) or of a mixture of compounds of Formula (I) and to specific methods for producing, imparting, modifying and/or intensifying specific flavor impressions.
- -
-
-
- Imidazo[1,2-a]pyridine-ylmethyl-derivatives and their use as flavoring agents
-
The present invention primarily relates to imidazo[1,2-a]pyridine-ylmethyl-derivatives of Formula (I) wherein R1, R2, X, W e J are as defined in the description, to mixtures thereof and to the use thereof as flavoring agents. The compounds in accordance with the present invention are suitable for producing, imparting, or intensifying an umami flavor. The invention further relates to flavoring mixtures, compositions for oral consumption as well as ready-to-eat, ready-to-use and semifinished products, comprising an effective amount of the compound of Formula (I) and to specific methods for producing, imparting, modifying and/or intensifying specific flavor impressions.
- -
-
-
- Molybdenum-catalyzed conversion of diols and biomass-derived polyols to alkenes using isopropyl alcohol as reductant and solvent
-
Chemical processes capable of reducing the high oxygen content of biomass-derived polyols are in demand in order to produce renewable substitutes for chemicals of fossil origin. Deoxydehydration (DODH) is an attractive reaction that in a single step transforms a vicinal diol into an alkene, but the reaction requires a homogeneous catalyst, a reductant, and a solvent, which are typically expensive, unsustainable, or inefficient. Herein, we present the use of molybdenum(VI)-based compounds, in particular the cheap and commercially available (NH4)6Mo7O24·4H2O, as catalysts for the DODH of vicinal diols in isopropyl alcohol (iPrOH), which serves as both the solvent and reductant. The reaction proceeds at 240-250 °C in a pressurized autoclave, and the alkene yield from simple aliphatic diols can be as high as 77%. The major byproducts are carbonyl compounds - formed by dehydration of the diol - and the alcohols formed by transfer hydrogenation of the carbonyl compounds; the total yield of reduced species (i.e., alkene and alcohols) can be as high as 92%. The DODH of glycerol yields allyl alcohol, which undergoes subsequent Mo-catalyzed deoxygenation to propylene driven by the oxidation of iPrOH; a major byproduct is the homocoupled product 1,5-hexadiene. Further insight in this Mo-catalyzed deoxygenation is gained by an investigation of model compounds: The allylic alcohol 1-hexen-3-ol is deoxygenated to hexene isomers in a yield of 65%, while benzyl alcohol is deoxygenated to toluene in a yield of 93%. The DODH of erythritol yields 39% 2,5-dihydrofuran, while the DODH of the proposed intermediate 1,4-anhydroerythritol yields 75%. The mechanism of the DODH of 1,4-anhydroerythritol was investigated by means of density functional theory (DFT), and the rate-determining step (24.1 kcal/mol) was found to be reduction of a molybdenum(VI) diolate to a molybdenum(IV) diolate.
- Dethlefsen, Johannes R.,Lupp, Daniel,Teshome, Ayele,Nielsen, Lasse B.,Fristrup, Peter
-
p. 3638 - 3647
(2015/06/16)
-
- Synthesis of methyl ketones from terminal olefins using PdCl 2/CrO3 system mimicking the Wacker process
-
An efficient synthesis of methyl ketones from terminal olefins using PdCl2/CrO3 system mimicking the Wacker process is developed. The method shows good functional groups compatibility, no aldehyde by-products and is operationally simple. CrO3 is the sole oxidant and replaces both Cu-salts and molecular oxygen, traditionally used in this process. The method holds potential for future applications in organic synthesis.
- Fernandes, Rodney A.,Bethi, Venkati
-
p. 4760 - 4767
(2014/06/24)
-
- Iron(III) sulfate as terminal oxidant in the synthesis of methyl ketones via wacker oxidation
-
An efficient and environmentally benign method using Fe(III) sulfate as a terminal oxidant in the synthesis of methyl ketones from terminal olefins via the Wacker process is developed. The methodology offers high selectivity for a Markonikov product, shows good functional group compatibility, involves mild reaction conditions, and is operationally simple. Fe2(SO 4)3 is the sole terminal oxidant in this process. The method holds potential for future applications in organic synthesis.
- Fernandes, Rodney A.,Chaudhari, Dipali A.
-
p. 5787 - 5793
(2014/07/08)
-
- Sunlight, electrochemistry, and sustainable oxidation reactions
-
Inexpensive, readily available photovoltaic cells have been used to conduct indirect electrochemical oxidation reactions. The reactions retain the efficiency of the solar-electrochemical method while capitalizing on the unique opportunities for selectivity afforded by a chemical oxidant. The versatility of the electrochemical method allowed for the recycling of Os(viii)-, TEMPO-, Ce(iv)-, Pd(ii)-, Ru(viii)-, and Mn(v)-oxidants all with the same very simple reaction apparatus.
- Nguyen, Bichlien H.,Redden, Alison,Moeller, Kevin D.
-
supporting information
p. 69 - 72
(2014/01/06)
-
- Fullerene as a platform for recyclable TEMPO organocatalysts for the oxidation of alcohols
-
[60]Fullerene has been employed successfully as a molecular platform to anchor 12 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) moieties. Such an octahedrally substituted C60-derivative has been employed as an organocatalyst for the oxidation of primary and secondary alcohols using the Anelli protocol. The reaction showed a general applicability to various alcohols, and the catalyst was recovered easily and could be recycled for at least seven cycles with no loss in catalytic activity. EPR spectroscopy studies revealed that the amount of radicals decreases during the catalytic cycles, even if the recovered material still displays unchanged catalytic activity. This new approach paves the way to use fullerene as a molecular platform to support other kinds of organometallic and organocatalysts as well as for their use as model compounds to understand the behavior of other nanocarbon-supported catalysts.
- Beejapur, Hazi Ahmad,Campisciano, Vincenzo,Franchi, Paola,Lucarini, Marco,Giacalone, Francesco,Gruttadauria, Michelangelo
-
p. 2419 - 2424
(2014/08/18)
-
