- Acid-Catalyzed Hydrolysis of Bridged Bi- and Tricyclic Compounds. 25. Comparison of the Hydrations of 2-Methyl-2-norbornene and 2-Methylenenorbornane with Those of 1-Methylcyclohexene and Methylenecyclohexane
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Hydration rates of 2-methyl-2-norbornene, 2-methylenenorbornane, 1-methylcyclohexene, and methylenecyclohexane were measured spectrophotometrically in aqueous perchloric acid.The activation parameters and solvent deuterium isotope effects are in all cases in agreement with the slow proton transfer to an olefinic carbon atom.The free energy diagrams show that the Gibbs energy of the transition state of protonation (hydration) is higher for methylenecycloalkanes than for methylcycloalkenes.The energy difference is small (0.8 kJ mol-1) in the case of the bicyclic olefins and large (11.5 kJ mol-1) in the case of the monocyclic olefins mentioned.Thus, no marked difference in the energies of the transition states caused by a possible distortion of the ?-orbitals of 2-methyl-2-norbornene can be seen in the hydrations of the bicyclic olefins.An explanation for the latter large difference is evidently a change of conformation during the protonation of 1-methylcyclohexene, which possibly also causes an exceptionally low isotope effect (kH/kD=1.13).
- Lajunen, Martti,Hiukka, Risto
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Read Online
- Products of ozone oxidation of some saturated cyclic hydrocarbons
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Low-temperature ozone oxidation of a series of saturated carbocyclic hydrocarbons afforded the corresponding alcohols and/or ketones in high yield through intermediate trioxidanes. exo,endo-Tetracyclo-[6.2.1.03,5]undecane-2,7-dione and exo,endo,endo-hexacyclo[9.3.1.03,8.04,6.05,9.012,14]pentadecane-2,10-dione were isolated, and exo,endo,exo-pentacyclo[6.3.1.02,7.03,5.09,11]dodecyl-, exo,exo,exo-heptacyclo-[9.3.1.02,10.03,8.04,6.05,9.012,14]pentadecyl, and 1-methylcyclohexyltrioxidanes were identified and characterized for the first time.
- Khalitova,Grabovskiy,Antipin,Spirikhin,Kabal'Nova
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Read Online
- Hydrogen-atom and oxygen-atom transfer reactivities of iron(
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A series of iron(ii) complexes with the general formula [FeII(L2-Qn)(L)]n+ (n = 1, L = F?, Cl?; n = 2, L = NCMe, H2O) have been isolated and characterized. The X-ray crystallographic data reveals that
- Banerjee, Sridhar,Haukka, Matti,Hossain, Md. Kamal,Huelsmann, Ricardo Dagnoni,Martendal, Edmar,Munshi, Sandip,Nordlander, Ebbe,Paine, Tapan K.,Peralta, Rosely,Singh, Reena,Sinha, Arup,Valiati, Andrei Felipe,Wendt, Ola F.,Xavier, Fernando,Yiga, Solomon
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supporting information
p. 870 - 884
(2022/02/01)
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- Deciphering Reactivity and Selectivity Patterns in Aliphatic C-H Bond Oxygenation of Cyclopentane and Cyclohexane Derivatives
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A kinetic, product, and computational study on the reactions of the cumyloxyl radical with monosubstituted cyclopentanes and cyclohexanes has been carried out. HAT rates, site-selectivities for C-H bond oxidation, and DFT computations provide quantitative information and theoretical models to explain the observed patterns. Cyclopentanes functionalize predominantly at C-1, and tertiary C-H bond activation barriers decrease on going from methyl- and tert-butylcyclopentane to phenylcyclopentane, in line with the computed C-H BDEs. With cyclohexanes, the relative importance of HAT from C-1 decreases on going from methyl- and phenylcyclohexane to ethyl-, isopropyl-, and tert-butylcyclohexane. Deactivation is also observed at C-2 with site-selectivity that progressively shifts to C-3 and C-4 with increasing substituent steric bulk. The site-selectivities observed in the corresponding oxidations promoted by ethyl(trifluoromethyl)dioxirane support this mechanistic picture. Comparison of these results with those obtained previously for C-H bond azidation and functionalizations promoted by the PINO radical of phenyl and tert-butylcyclohexane, together with new calculations, provides a mechanistic framework for understanding C-H bond functionalization of cycloalkanes. The nature of the HAT reagent, C-H bond strengths, and torsional effects are important determinants of site-selectivity, with the latter effects that play a major role in the reactions of oxygen-centered HAT reagents with monosubstituted cyclohexanes.
- Martin, Teo,Galeotti, Marco,Salamone, Michela,Liu, Fengjiao,Yu, Yanmin,Duan, Meng,Houk,Bietti, Massimo
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supporting information
p. 9925 - 9937
(2021/06/30)
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- Cationic nickel(II) pyridinophane complexes: Synthesis, structures and catalytic activities for C-H oxidation
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A series of nickel(II) pyridinophane complexes were synthesized and characterized by X-ray crystallographic analysis. Their IR spectra supported the existence of mononuclear nickel(II) complexes in solution. Furthermore, we conducted catalytic CH oxidation of cyclooctane with nickel(II) pyridinophanes as the catalysts. The activity of nickel(II) pyridinophanes was affected by steric hindrance around the nitrogen atoms.
- Nishimura, Tsubasa,Ando, Yuki,Shinokubo, Hiroshi,Miyake, Yoshihiro
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supporting information
p. 1049 - 1052
(2021/05/19)
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- Aliphatic C–H hydroxylation activity and durability of a nickel complex catalyst according to the molecular structure of the bis(oxazoline) ligands
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Applicability of the oxazoline-based compounds, bis(2-oxazolynyl)methane (BOX) and 2,6-bis(2-oxazolynyl)pyridine (PyBOX), as supporting ligands of nickel(II) complexes for the catalysis of aliphatic C–H hydroxylation with m-CPBA (meta-chloroperoxybenzoic acid) was explored. Substituent groups at the fourth and fifth positions of oxazoline rings and the bridgehead carbon atom of the BOX derivatives affected the catalytic performances toward cyclohexane hydroxylation. Presence of dioxygen led to a reduced catalytic performance of the nickel complexes, except in the case of a fully substituted BOX ligand complex.
- Hikichi, Shiro,Izumi, Takashi,Matsuba, Naki,Nakazawa, Jun
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- Efficient alkane hydroxylation catalysis of nickel(ii) complexes with oxazoline donor containing tripodal tetradentate ligands
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Tris(oxazolynylmethyl)amine TOAR(where R denotes the substituent groups on the fourth position of the oxazoline rings) complexes of nickel(ii) have been synthesized as catalyst precursors for alkane oxidation withmeta-chloroperoxybenzoic acid (m-CPBA). The molecular structures of acetato, nitrato,meta-chlorobenzoato and chlorido complexes with TOAMe2have been determined using X-ray crystallography. The bulkiness of the substituent groups R affects the coordination environment of the nickel(ii) centers, as has been demonstrated by comparison of the molecular structures of chlorido complexes with TOAMe2and TOAtBu. The nickel(ii)-acetato complex with TOAMe2is an efficient catalyst precursor compared with the tris(pyridylmethyl)amine (TPA) analogue. Oxazolynyl donors’ strong s-electron donating ability will enhance the catalytic activity. Catalytic reaction rates and substrate oxidizing position selectivity are controlled by the structural properties of the R of TOAR. Reaction of the acetato complex with TOAMe2andm-CPBA yields the corresponding acylperoxido species, which can be detected using spectroscopy. Kinetic studies of the decay process of the acylperoxido species suggest that the acylperoxido species is a precursor of an active species for alkane oxidation.
- Hikichi, Shiro,Horii, Sena,Nakazawa, Jun,Okamura, Masaya,Terao, Ikumi
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p. 6108 - 6118
(2020/05/25)
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- Homogeneous catalytic oxidation of alkenes employing mononuclear vanadium complex with hydrogen peroxide
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Abstract: Homogeneous liquid-phase oxidation of alkenes (allylbenzene, cis-cyclooctene, 4-chlorostyrene, styrene, 2-norbornene, 1-methyl cyclohexene, indene, lemonine, and 1-hexene) were catalyzed by using vanadium complex [VO(hyap)(acac)2] in existence of H2O2. The complex [VO(hyap)(acac)2] was formed as a crystal by the reaction of [VO(acac)2] and 2-hydroxyacetophenone (hyap) in the presence of methanol by refluxing the reaction mixture. Various analytical and spectroscopic techniques, namely FTIR, ESI–MS, UV–Vis, single-crystal XRD, and EPR, were used to analyze and optimize the structure of the complexes. Graphic abstract: [Figure not available: see fulltext.].
- Maurya, Abhishek
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p. 3261 - 3269
(2020/07/14)
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- Metal-Organic Architectures Assembled from Multifunctional Polycarboxylates: Hydrothermal Self-Assembly, Structures, and Catalytic Activity in Alkane Oxidation
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A three-component aqueous reaction system comprising copper(II) acetate (metal node), poly(carboxylic acid) with a phenylpyridine or biphenyl core (main building block), and 1,10-phenanthroline (crystallization mediator) was investigated under hydrothermal conditions. As a result, four new coordination compounds were self-assembled, namely, {[Cu(μ3-cpna)(phen)]·H2O}n (1), {[Cu(μ-Hbtc)(phen)]·H2O}n (2), {[Cu(μ3-Hcpic)(phen)]·2H2O}n (3), and [Cu6(μ-Hcptc)6(phen)6]·6H2O (4), where H2cpna = 5-(2′-carboxylphenyl)nicotinic acid, H3btc = biphenyl-2,4,4′-tricarboxylic acid, H3cpic = 4-(5-carboxypyridin-2-yl)isophthalic acid, H3cptc = 2-(4-carboxypyridin-3-yl)terephthalic acid, and phen = 1,10-phenanthroline. Crystal structures of compounds 1-3 reveal that they are 1D coordination polymers with a ladder, linear, or double-chain structure, while product 4 is a 0D hexanuclear complex. All of the structures are extended further [1D a?' 2D (1 and 2), 1D a?' 3D (3), and 0D a?' 3D (4)] into hydrogen-bonded networks. The type of a multicarboxylate building block has a considerable effect on the final structures of 1-4. The magnetic behavior and thermal stability of 1-4 were also investigated. Besides, these copper(II) derivatives efficiently catalyze the oxidation of cycloalkanes with hydrogen peroxide under mild conditions. The obtained products are the unique examples of copper derivatives that were assembled from H2cpna, H3btc, H3cpic, and H3cptc, thus opening up their use as multicarboxylate ligands toward the design of copper-organic architectures.
- Gu, Jinzhong,Wen, Min,Cai, Yan,Shi, Zifa,Arol, Aliaksandr S.,Kirillova, Marina V.,Kirillov, Alexander M.
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p. 2403 - 2412
(2019/02/28)
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- Polymer-anchored mononuclear and binuclear CuII Schiff-base complexes: Impact of heterogenization on liquid phase catalytic oxidation of a series of alkenes
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Liquid phase catalytic oxidation of a number of alkenes, for example, cyclohexene, cis-cyclooctene, styrene, 1-methyl cyclohexene and 1-hexene, was performed using polymer-anchored copper (II) complexes PS-[Cu (sal-sch)Cl] (5), PS-[Cu (sal-tch)Cl] (6), PS-[CH2{Cu (sal-sch)Cl}2] (7) and PS-[CH2{Cu (sal-tch)Cl}2] (8). Neat complexes [Cu (sal-sch)Cl] (1), [Cu (sal-tch)Cl] (2), [CH2{Cu (sal-sch)Cl}2] (3) and [CH2{Cu (sal-tch)Cl}2] (4) were isolated by reacting CuCl2·2H2O with [Hsal-sch] (I), [Hsal-tch] (II), [H2bissal-sch] (III) and [H2bissal-tch] (IV), respectively, in refluxing methanol. Complexes 1–4 have been covalently anchored in Merrifield resin through the amine nitrogen of the semicarbazide or thiosemicarbazide moiety. A number of analytical, spectroscopic and thermal techniques, such as CHNS analysis, Fourier transform-infrared, UV–Vis, PMR, 13C-NMR, electron paramagnetic resonance, scanning electron microscopy, energy-dispersive X-ray analysis, thermogravimetric analysis, atomic force microscopy, atomic absorption spectroscopy, and electrospray ionization-mass spectrometry, were used to analyze and establish the molecular structure of the ligands (I)–(IV) and complexes (1)–(8) in solid state as well as in solution state. Grafted complexes 5–8 were employed as active catalysts for the oxidation of a series of alkenes in the presence of hydrogen peroxide. Copper hydroperoxo species ([CuIII (sal-sch)-O-O-H]), which is believed to be the active intermediate, generated during the catalytic oxidation of alkenes, are identified. It was found that supported catalysts are very economical, green and efficient in contrast to their neat complexes as well as most of the recently reported heterogeneous catalysts.
- Maurya, Abhishek,Kesharwani, Neha,Kachhap, Payal,Mishra, Vivek Kumar,Chaudhary, Nikita,Haldar, Chanchal
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- Controllable Intramolecular Unactivated C(sp3)-H Amination and Oxygenation of Carbamates
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Dual catalyst-controlled intramolecular unactivated C(sp3)-H amination and oxygenation of carbamates merging visible-light photocatalysis and earth-abundant transition metal catalysis have been reported. Useful amino alcohol and diol derivatives could be selectively obtained from readily available tertiary alcohol derivatives. The possible mechanisms have been proposed via a 1,5-HAT process followed by Lewis acid-controlled cyclization. The nickel and zinc catalysts inhibit the formation of oxygenation and amination products, respectively. An interesting phenomenon of chirality transfer is also observed.
- Guo, Qihang,Ren, Xiang,Lu, Zhan
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supporting information
p. 880 - 884
(2019/05/16)
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- A 1 - methyl cyclohexyl methyl acrylate preparation method (by machine translation)
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The invention relates to a 1 - methyl cyclohexyl methyl acrylate preparation method, comprising the following steps: S1: under protection of inert gas, and in which there is at least catalyst 1st, 2nd catalyst and under the condition that the polymerization inhibitor, the 1 - methyl cyclohexanol with methyl acrylic chloride in reaction of organic solvent, to obtain 1 - methyl cyclohexyl methyl acrylate reaction mixture; S2: are water, acidic solution, water and alkaline solution to wash the 1st reaction mixture, the aqueous phase and the 4th 4th layered obtained organic phase; S3: to the 4th organic phase dried, concentrated and rectification, when the temperature is stabilized at 68 °C about 5 minutes later, collects the host fraction, get colorless transparent liquid 1 - methyl cyclohexyl methyl acrylate. Beneficial effect of the application is at the same time using straight chain alkylamine and aromatic amine as catalyst to catalyze 1 - methyl cyclohexyl alcohol and methacrylic chloride reaction, can remarkably improve the product yield, reduce the content of the impurities in the product. (by machine translation)
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Paragraph 0030-0038
(2019/04/06)
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- PROCESS FOR MAKING FORMIC ACID UTILIZING LOWER-BOILING FORMATE ESTERS
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Disclosed is a process for recovering formic acid from a formate ester of a C3 to C4 alcohol. Disclosed is also a process for producing formic acid by carbonylating a C3 to C4 alcohol, hydrolyzing the formate ester of the alcohol, and recovering a formic acid product. The alcohol may be dried and returned to the reactor. The process enables a more energy efficient production of formic acid than the carbonylation of methanol to produce methyl formate.
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Paragraph 00177; 00178
(2019/02/15)
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- New copper(II) coordination compounds assembled from multifunctional pyridine-carboxylate blocks: Synthesis, structures, and catalytic activity in cycloalkane oxidation
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Two new copper(II) coordination compounds, namely a 1D coordination polymer [Cu(μ-cpna)(phen)(H2O)]n (1) and a discrete tetracopper(II) derivative [Cu(phen)2(H2O)]2[Cu2(μ-Hdppa)2(Hdppa)2] (2), were hydrothermally synthesized from copper(II) chloride as a metal source, 5-(4-carboxyphenoxy)nicotinic acid (H2cpna) or 5-(3,4-dicarboxylphenyl)picolinic acid (H3dppa) as a principal building block, and 1,10-phenanthroline (phen) as a crystallization mediator. Compounds 1 and 2 were isolated as air-stable microcrystalline solids and fully characterized by elemental and thermogravimetric analyses, IR spectroscopy, powder and single-crystal X-ray diffraction. In the solid state, the structure of 1 discloses the linear interdigitated 1D coordination polymer chains with the 2C1 topology. The crystal structure of an ionic derivative 2 shows that the mono-and dicopper(II) units are extended into the intricate 1D hydrogen-bonded chains with the SP 1-periodic net (4,4)(0,2) topology. Thermal stability and catalytic properties of 1 and 2 were also investigated. In fact, both Cu derivatives act as efficient homogeneous catalysts (catalyst precursors) for the mild oxidation of cycloalkanes by hydrogen peroxide to give the corresponding alcohols and ketones; the substrate scope and the effects of type and amount of acid promoter as well as bond-, regio-, and stereo-selectivity features were investigated.
- Zhao, Na,Li, Yu,Gu, Jinzhong,Fernandes, Tiago A.,Kirillova, Marina V.,Kirillov, Alexander M.
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supporting information
(2019/01/14)
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- Synthesis, structural characterization and C–H activation property of a tetra-iron(III) cluster
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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
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p. 220 - 226
(2019/01/05)
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- Highly Selective and Catalytic Oxygenations of C?H and C=C Bonds by a Mononuclear Nonheme High-Spin Iron(III)-Alkylperoxo Species
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The reactivity of a mononuclear high-spin iron(III)-alkylperoxo intermediate [FeIII(t-BuLUrea)(OOCm)(OH2)]2+(2), generated from [FeII(t-BuLUrea)(H2O)(OTf)](OTf) (1) [t-BuLUrea=1,1′-(((pyridin-2-ylmethyl)azanediyl)bis(ethane-2,1-diyl))bis(3-(tert-butyl)urea), OTf=trifluoromethanesulfonate] with cumyl hydroperoxide (CmOOH), toward the C?H and C=C bonds of hydrocarbons is reported. 2 oxygenates the strong C?H bonds of aliphatic substrates with high chemo- and stereoselectivity in the presence of 2,6-lutidine. While 2 itself is a sluggish oxidant, 2,6-lutidine assists the heterolytic O?O bond cleavage of the metal-bound alkylperoxo, giving rise to a reactive metal-based oxidant. The roles of the urea groups on the supporting ligand, and of the base, in directing the selective and catalytic oxygenation of hydrocarbon substrates by 2 are discussed.
- Ghosh, Ivy,Banerjee, Sridhar,Paul, Satadal,Corona, Teresa,Paine, Tapan Kanti
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p. 12534 - 12539
(2019/08/07)
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- Bioinspired Olefin cis-Dihydroxylation and Aliphatic C-H Bond Hydroxylation with Dioxygen Catalyzed by a Nonheme Iron Complex
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A mononuclear iron(II)-α-hydroxy acid complex [(TpPh,Me)FeII(benzilate)] (TpPh,Me = hydrotris(3-phenyl-5-methylpyrazol-1-yl)borate) of a facial tridentate ligand has been isolated and characterized to explore its catalytic efficiency for aerial oxidation of organic substrates. In the reaction between the iron(II)-benzilate complex and O2, the metal-coordinated benzilate is stoichiometrically converted to benzophenone with concomitant reduction of dioxygen on the iron center. Based on the results from interception experiments and labeling studies, different iron-oxygen oxidants are proposed to generate in situ in the reaction pathway depending upon the absence or presence of an external additive (such as protic acid or Lewis acid). The five-coordinate iron(II) complex catalytically cis-dihydroxylates olefins and oxygenates the C-H bonds of aliphatic substrates using O2 as the terminal oxidant. The iron(II) complex exhibits better catalytic activity in the presence of a Lewis acid.
- Chatterjee, Sayanti,Bhattacharya, Shrabanti,Paine, Tapan Kanti
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p. 10160 - 10169
(2018/08/28)
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- Arylruthenium(III) Porphyrin-Catalyzed C-H Oxidation and Epoxidation at Room Temperature and [RuV(Por)(O)(Ph)] Intermediate by Spectroscopic Analysis and Density Functional Theory Calculations
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The development of highly active and selective metal catalysts for efficient oxidation of hydrocarbons and identification of the reactive intermediates in the oxidation catalysis are long-standing challenges. In the rapid hydrocarbon oxidation catalyzed by ruthenium(IV) and -(III) porphyrins, the putative Ru(V)-oxo intermediates remain elusive. Herein we report that arylruthenium(III) porphyrins are highly active catalysts for hydrocarbon oxidation. Using catalyst [RuIII(TDCPP)(Ph)(OEt2)] (H2TDCPP = 5,10,15,20-tetrakis(2,6-dichlorophenyl)porphyrin), the oxidation of C-H bonds of various hydrocarbons with oxidant m-CPBA at room temperature gave alcohols/ketones in up to 99% yield within 1 h; use of [nBu4N]IO4 as a mild alternative oxidant avoided formation of lactone from cyclic ketone in C-H oxidation, and the catalytic epoxidation with up to 99% yield and high selectivity (no aldehydes as side product) was accomplished within 5 min. UV-vis, electrospray ionization-mass spectrometry, resonance Raman, electron paramagnetic resonance, and kinetic measurements and density functional theory calculations lend evidence for the formation of Ru(V)-oxo intermediate [RuV(TDCPP)(O)(Ph)].
- Shing, Ka-Pan,Cao, Bei,Liu, Yungen,Lee, Hung Kay,Li, Ming-De,Phillips, David Lee,Chang, Xiao-Yong,Che, Chi-Ming
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supporting information
p. 7032 - 7042
(2018/06/12)
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- Interplay between H-bonding and interpenetration in an aqueous copper(ii)-aminoalcohol-pyromellitic acid system: self-assembly synthesis, structural features and catalysis
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Two new copper(ii) coordination compounds, [Cu(H1.5mdea)2]2(H2pma) (1a) and [{Cu2(μ-Hmdea)2}2(μ4-pma)]n·2nH2O (1b), were self-assembled at different temperatures from the same multicomponent reaction system, comprising copper(ii) nitrate, N-methyldiethanolamine (H2mdea), pyromellitic acid (H4pma), and potassium hydroxide. Products 1a and 1b were isolated as microcrystalline solids and fully characterized and their structures were established by single-crystal X-ray diffraction. Compound 1a features the bis-aminoalcohol(ate) monocopper(ii) units and H2pma2? anions that are multiply interconnected by strong H-bonds into a firm 2D H-bonded layer. Compound 1b reveals the bis-aminoalcoholate dicopper(ii) motifs that are interlinked by the μ4-pma4? spacers into a 3D + 3D interpenetrated metal-organic framework. From a topological perspective, both networks of 1a and 1b are uninodal and driven by similar 4-connected H2pma2? or pma4? nodes, but result in distinct sql and dia topologies, respectively. Compound 1a was applied as an efficient catalyst for two model cycloalkane functionalization reactions: (1) oxidation by H2O2 to form cyclic alcohols and ketones and (2) hydrocarboxylation by CO/H2O and S2O82? to form cycloalkanecarboxylic acids. The substrate scope, effects of various reaction parameters, selectivity and mechanistic features were also investigated.
- Fernandes, Tiago A.,Kirillova, Marina V.,André, Vania,Kirillov, Alexander M.
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p. 16674 - 16683
(2018/12/05)
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- Cis -Oxoruthenium complexes supported by chiral tetradentate amine (N4) ligands for hydrocarbon oxidations
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We report the first examples of ruthenium complexes cis-[(N4)RuIIICl2]+ and cis-[(N4)RuII(OH2)2]2+ supported by chiral tetradentate amine ligands (N4), together with a high-valent cis-dioxo complex cis-[(N4)RuVI(O)2]2+ supported by the chiral N4 ligand mcp (mcp = N,N′-dimethyl-N,N′-bis(pyridin-2-ylmethyl)cyclohexane-1,2-diamine). The X-ray crystal structures of cis-[(mcp)RuIIICl2](ClO4) (1a), cis-[(Me2mcp)RuIIICl2]ClO4 (2a) and cis-[(pdp)RuIIICl2](ClO4) (3a) (Me2mcp = N,N′-dimethyl-N,N′-bis((6-methylpyridin-2-yl)methyl)cyclohexane-1,2-diamine, pdp = 1,1′-bis(pyridin-2-ylmethyl)-2,2′-bipyrrolidine)) show that the ligands coordinate to the ruthenium centre in a cis-α configuration. In aqueous solutions, proton-coupled electron-transfer redox couples were observed for cis-[(mcp)RuIII(O2CCF3)2]ClO4 (1b) and cis-[(pdp)RuIII(O3SCF3)2]CF3SO3 (3c′). Electrochemical analyses showed that the chemically/electrochemically generated cis-[(mcp)RuVI(O)2]2+ and cis-[(pdp)RuVI(O)2]2+ complexes are strong oxidants with E° = 1.11-1.13 V vs. SCE (at pH 1) and strong H-atom abstractors with DO-H = 90.1-90.8 kcal mol-1. The reaction of 1b or its (R,R)-mcp counterpart with excess (NH4)2[CeIV(NO3)6] (CAN) in aqueous medium afforded cis-[(mcp)RuVI(O)2](ClO4)2 (1e) or cis-[((R,R)-mcp)RuVI(O)2](ClO4)2 (1e?), respectively, a strong oxidant with E(RuVI/V) = 0.78 V (vs. Ag/AgNO3) in acetonitrile solution. Complex 1e oxidized various hydrocarbons, including cyclohexane, in acetonitrile at room temperature, affording alcohols and/or ketones in up to 66% yield. Stoichiometric oxidations of alkenes by 1e or 1e? in tBuOH/H2O (5:1 v/v) afforded diols and aldehydes in combined yields of up to 98%, with moderate enantioselectivity obtained for the reaction using 1e?. The cis-[(pdp)RuII(OH2)2]2+ (3c)-catalysed oxidation of saturated C-H bonds, including those of ethane and propane, with CAN as terminal oxidant was also demonstrated.
- Tse, Chun-Wai,Liu, Yungen,Wai-Shan Chow, Toby,Ma, Chaoqun,Yip, Wing-Ping,Chang, Xiao-Yong,Low, Kam-Hung,Huang, Jie-Sheng,Che, Chi-Ming
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p. 2803 - 2816
(2018/03/21)
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- New oxidovanadium(iv) complex with a BIAN ligand: synthesis, structure, redox properties and catalytic activity
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Reaction of VCl3 with bis[N-(2,6-diisopropylphenyl)imino]acenaphthene (dpp-bian) in air afforded [VOCl2(dpp-bian)] (1). The complex was characterized by IR and UV-vis spectroscopies and elemental analysis. The crystal structure of 1 was determined by X-ray diffraction (XRD) analysis. The vanadium atom is in a square-pyramidal OCl2N4 coordination environment. The cyclic voltammogram (CV) in dichloromethane reveals an irreversible oxidation process at +1.40 V (vs. Ag/AgCl) assigned to the V(iv)/V(v) couple, and two consecutive quasi-reversible one-electron reduction processes at ?0.32 V and ?1.05 V (vs. Ag/AgCl), respectively, assigned to the bian/bian?/ and bian?//bian2? couples, followed by irreversible reduction at ?1.6 V (vs. Ag/AgCl). The EPR spectrum of 1 in toluene shows a single 8-line signal typical for oxidovanadium(iv) complexes with d1 configuration. The magnetic behavior of 1 confirms the presence of one unpaired electron (μeff (330 K) = 1.67 μB), and the isolation of the paramagnetic centers. Application of 1 to oxidation of alkanes documented high catalytic activity under mild conditions. The kinetics and selectivity of alkane oxygenation by the 1/H2O2 and 1/PCA/H2O2 systems (PCA is pyrazine-2-carboxylic acid) were studied. The reaction is more efficient in the presence of PCA.
- Fomenko, Iakov S.,Gushchin, Artem L.,Shul'pina, Lidia S.,Ikonnikov, Nikolay S.,Abramov, Pavel A.,Romashev, Nikolay F.,Poryvaev, Artem S.,Sheveleva, Alena M.,Bogomyakov, Artem S.,Shmelev, Nikita Y.,Fedin, Matvey V.,Shul'pin, Georgiy B.,Sokolov, Maxim N.
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supporting information
p. 16200 - 16210
(2018/10/04)
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- Ru-Photoredox-Catalyzed Decarboxylative Oxygenation of Aliphatic Carboxylic Acids through N-(acyloxy)phthalimide
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Decarboxylative aminoxylation of aliphatic carboxylic acid derivatives with (2,2,6,6-tetramethylpiperidin-1-yl)oxyl (TEMPO) in the presence of ruthenium photoredox catalysis is reported. The key transformation entails a highly efficient photoredox catalytic cycle using Hantzsch ester as a reductant. The ensuing alkoxyamine can be readily converted to the corresponding alcohol in one pot, representing an alternative approach to access aliphatic alcohols under photoredox conditions.
- Zheng, Chao,Wang, Yuting,Xu, Yangrui,Chen, Zhen,Chen, Guangying,Liang, Steven H.
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p. 4824 - 4827
(2018/08/24)
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- Mild and Regioselective Hydroxylation of Methyl Group in Neocuproine: Approach to an N,O-Ligated Cu6 Cage Phenylsilsesquioxane
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The self-Assembly synthesis of Cu(II)-silsesquioxane involving 2,9-dimethyl-1,10-phenanthroline (neocuproine) as an additional N ligand at copper atoms was performed. The reaction revealed an unprecedented aerobic hydroxylation of only one of the two methyl groups in neocuproine to afford the corresponding geminal diol. The produced derivative of oxidized neocuproine acts as a two-centered N,O ligand in the assembly of the hexacopper cage product [Cu6(Ph5Si5O10)2·(C14H11N2O2)2] (1), coordinating two of the six copper centers in the product. Two siloxanolate ligands [PhSi(O)O]5 in the cis configuration coordinate to the rest of the copper(II) ions. Compound 1 is a highly efficient homogeneous precatalyst in the oxidation of alkanes and alcohols with peroxides.
- Bilyachenko, Alexey N.,Levitsky, Mikhail M.,Khrustalev, Victor N.,Zubavichus, Yan V.,Shul'Pina, Lidia S.,Shubina, Elena S.,Shul'Pin, Georgiy B.
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supporting information
p. 168 - 171
(2018/02/06)
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- Heptanuclear Fe5Cu2-Phenylgermsesquioxane containing 2,2′-Bipyridine: Synthesis, Structure, and Catalytic Activity in Oxidation of C-H Compounds
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A new representative of an unusual family of metallagermaniumsesquioxanes, namely the heterometallic cagelike phenylgermsesquioxane (PhGeO2)12Cu2Fe5(O)OH(PhGe)2O5(bipy)2 (2), was synthesized and structurally characterized. Fe(III) ions of the complex are coordinated by oxa ligands: (i) cyclic (PhGeO2)12 and acyclic (Ph2Ge2O5) germoxanolates and (ii) O2- and (iii) HO- moieties. In turn, Cu(II) ions are coordinated by both oxa (germoxanolates) and aza ligands (2,2′-bipyridines). This "hetero-type" of ligation gives in sum an attractive pagoda-like molecular architecture of the complex 2. Product 2 showed a high catalytic activity in the oxidation of alkanes to the corresponding alkyl hydroperoxides (in yields up to 30%) and alcohols (in yields up to 100%) and in the oxidative formation of benzamides from alcohols (catalyst loading down to 0.4 mol % in Cu/Fe).
- Bilyachenko, Alexey N.,Khrustalev, Victor N.,Zubavichus, Yan V.,Shul'Pina, Lidia S.,Kulakova, Alena N.,Bantreil, Xavier,Lamaty, Frédéric,Levitsky, Mikhail M.,Gutsul, Evgeniy I.,Shubina, Elena S.,Shul'Pin, Georgiy B.
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p. 528 - 534
(2018/01/11)
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- Efficient Catalytic Greenhouse Gas-Free Hydrogen and Aldehyde Formation from Alcohols
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Catalytic preparation of hydrogen and aldehyde(s) from alcohols, including bioalcohols, without production of carbon monoxide or carbon dioxide.
- -
-
Paragraph 0053; 0054; 0148
(2017/11/07)
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- Alkane oxidation catalysed by a self-folded multi-iron complex
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A preorganised ligand scaffold is capable of coordinating multiple Fe(II) centres to form an electrophilic CH oxidation catalyst. This catalyst oxidises unactivated hydrocarbons including simple, linear alkanes under mild conditions in good yields with selectivity for the oxidation of secondary CH bonds. Control complexes containing a single metal centre are incapable of oxidising unstrained linear hydrocarbons, indicating that participation of multiple centres aids the CH oxidation of challenging substrates.
- Mettry, Magi,Moehlig, Melissa Padilla,Gill, Adam D.,Hooley, Richard J.
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p. 120 - 128
(2016/11/09)
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- Synthesis, crystal structures and catalytic activity of Cu(II) and Mn(III) Schiff base complexes: Influence of additives on the oxidation catalysis of cyclohexane and 1-phenylehanol
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The complexes of copper [Cu(κONN’-HL)(NO3)(DMF)](NO3)?H2O (1) and [Cu(κONN’-HL)Cl2]??DMSO (2), and of manganese [Mn(κON-HL)2Cl2]Cl (3) and [Mn(κON-HL)2(NO3)2](NO3)?H2O (4) were synthesized by reactions of the respective chloride or nitrate salt with a non-aqueous solutions of the Schiff base aminoalcohol HL (product of condensation of salicylic aldehyde and aminoethylpiperazine) and characterized by X-ray diffraction analysis. The catalytic investigations disclosed a prominent activity of the copper compounds 1 and 2 towards oxidation of cyclohexane with hydrogen peroxide in the presence of various promoters (nitric, hydrochloric, oxalic acids and pyridine), under mild conditions. The unusual promoting effect of pyridine on the catalytic activity of the copper catalysts allowed to achieve yields up to 21% based on cyclohexane. Chromatographic studies revealed that cyclohexyl hydroperoxide is a main reaction product and chlorocyclohexane (in the presence of HCl as promoter) was also detected, suggesting a free radical reaction pathway with hydroxyl radicals as attacking species. Complexes 1 and 2 act also as catalysts in the oxidation of 1-phenylethanol with tert-butylhydroperoxide, showing acetophenone yields up to 62% and TON (turnover numbers) up to 620 in the presence of the K2CO3 promoter.
- Nesterova, Oksana V.,Nesterov, Dmytro S.,Krogul-Sobczak, Agnieszka,Guedes da Silva, M. Fátima C.,Pombeiro, Armando J.L.
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p. 506 - 515
(2016/12/16)
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- Synthesis, structures and catalytic activity of p-tolylimido rhenium(V) complexes incorporating quinoline-derived ligands
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p-Tolylimido rhenium(V) complexes, trans-(Cl,Cl)-[Re(p-NC6H4CH3)Cl2(4-MeO-quin-2-COO)(PPh3)] (1), trans-(Br,Br)-[Re(p-NC6H4CH3)Br2(4-MeO-quin-2-COO)(PPh3)]·2MeCN (2), trans-(Cl,Cl)-[Re(p-NC6H4CH3)Cl2(isoquin-1-COO)(PPh3)] (3), trans-(Br,Br)-[Re(p-NC6H4CH3)Br2(isoquin-1-COO)(PPh3)] (4), cis-(Cl,Cl)-[Re(p-NC6H4CH3)Cl2(4-MeO-quin-2-COO)(PPh3)] (5), cis-(Br,Br)-[Re(p-NC6H4CH3)Br2(4-MeO-quin-2-COO)(PPh3)]·MeOH (6), cis-(Cl,Cl)-[Re(p-NC6H4CH3)Cl2(isoquin-1-COO)(PPh3)] (7) and cis-(Br,Br)-[Re(p-NC6H4CH3)Br2(isoquin-1-COO)(PPh3)] (8), have been synthesized and characterized using X-ray analysis and spectroscopic methods (IR,1H,13C and31P NMR, UV–Vis). To elucidate the structural, spectroscopic and bonding properties, the theoretical calculations at the DFT level were undertaken for 1, 3, 5 and 7. The synthesized complexes exhibited moderate activity in the oxidation of 1-phenylethanol and certain alkanes (n-heptane and methylcyclohexane) with tert-butyl hydroperoxide (TBHP) in acetonitrile. Chromatograms of products obtained from the alkanes indicated that a sufficient sterical hindrance exists around of the rhenium catalytic center.
- Gryca,Machura,Shul'pina, Lidia S.,Shul'pin, Georgiy B.
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supporting information
p. 683 - 695
(2016/12/02)
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- Reactivity of a Carbon-Supported Single-Site Molybdenum Dioxo Catalyst for Biodiesel Synthesis
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A single-site molybdenum dioxo catalyst, (Oc)2Mo(=O)2@C, was prepared via direct grafting of MoO2Cl2(dme) (dme = 1,2-dimethoxyethane) on high-surface-area activated carbon. The physicochemical and chemical properties of this catalyst were fully characterized by N2 physisorption, ICP-AES/OES, PXRD, STEM, XPS, XAS, temperature-programmed reduction with H2 (TPR-H2), and temperature-programmed NH3 desorption (TPD-NH3). The single-site nature of the Mo species is corroborated by XPS and TPR-H2 data, and it exhibits the lowest reported MoOx Tmax of reduction reported to date, suggesting a highly reactive MoVI center. (Oc)2Mo(=O)2@C catalyzes the transesterification of a variety of esters and triglycerides with ethanol, exhibiting high activity at moderate temperatures (60-90 °C) and with negligible deactivation. (Oc)2Mo(=O)2@C is resistant to water and can be recycled at least three times with no loss of activity. The transesterification reaction is determined experimentally to be first order in [ethanol] and first order in [Mo] with Δ;H? = 10.5(8) kcal mol-1 and Δ;S? = -32(2) eu. The low energy of activation is consistent with the moderate conditions needed to achieve rapid turnover. This highly active carbon-supported single-site molybdenum dioxo species is thus an efficient, robust, and low-cost catalyst with significant potential for transesterification processes.
- Mouat, Aidan R.,Lohr, Tracy L.,Wegener, Evan C.,Miller, Jeffrey T.,Delferro, Massimiliano,Stair, Peter C.,Marks, Tobin J.
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p. 6762 - 6769
(2016/10/18)
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- Highly efficient hybrid cobalt-copper-aluminum layered double hydroxide/graphene nanocomposites as catalysts for the oxidation of alkylaromatics
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The selective oxidation of alkylaromatics is of vital importance for the production of high-added-value raw materials. The development of highly efficient heterogeneous catalytic oxidation systems under mild conditions has become an attractive research area. In this work, hybrid Co-Cu-Al layered double hydroxide/graphene (CoCuAl-LDH/graphene) nanocomposites, which were assembled successfully by a one-step coprecipitation route without the use of any additional reducing agents, were used as highly efficient catalysts for the liquid-phase selective oxidation of ethylbenzene using tert-butyl hydroperoxide as the oxidant. A series of characterizations revealed that graphene could stabilize CoCuAl-LDH nanoplatelets effectively in the nanocomposites, and in turn, highly dispersed CoCuAl-LDH could prevent the aggregation of the graphene nanosheets. By fine-tuning the mass ratio of graphene to CoCuAl-LDH, such nanocomposites offered a tunable catalytic oxidation performance. In particular, the nanocomposite with the graphene/CoCuAl-LDH mass ratio of 0.4:1 exhibited a remarkable catalytic performance with a considerable conversion (96.8 %) and selectivity to acetophenone (>95.0 %), which was mainly attributed to the synergism between the active CoCuAl-LDH component and the graphene matrix in the unique hetero-nanostructure. Moreover, the as-assembled nanocomposite catalysts displayed good recyclability and were active for the selective oxidation of other alkylaromatics. Mega results for nanocomposites: The liquid-phase selective oxidation of alkylaromatics is conducted successfully on well-dispersed hybrid Co-Cu-Al layered double hydroxide/graphene nanocomposites, which show an excellent catalytic performance attributable to the synergy between the active Co-Cu-Al layered double hydroxide component and the graphene matrix in the unique hetero-nanostructure of the nanocomposites.
- Xie, Renfeng,Fan, Guoli,Yang, Lan,Li, Feng
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p. 363 - 371
(2016/02/05)
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- Novel cage-like hexanuclear nickel(II) silsesquioxane. Synthesis, structure, and catalytic activity in oxidations with peroxides
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New hexanuclear nickel(II) silsesquioxane [(PhSiO1.5)12(NiO)6(NaCl)] (1) was synthesized as its dioxane-benzonitrile-water complex (PhSiO1,5)12(NiO)6(NaCl)(C4H8O2)13(PhCN)2(H2O)2 and studied by X-ray and topological analysis. The compound exhibits cylinder-like type of molecular architecture and represents very rare case of polyhedral complexation of metallasilsesquioxane with benzonitrile. Complex 1 exhibited catalytic activity in activation of such small molecules as light alkanes and alcohols. Namely, oxidation of alcohols with tert-butylhydroperoxide and alkanes with meta-chloroperoxybenzoic acid. The oxidation of methylcyclohexane gave rise to the isomeric ketones and unusual distribution of alcohol isomers.
- Bilyachenko, Alexey N.,Yalymov, Alexey I.,Shul'pina, Lidia S.,Mandelli, Dalmo,Korlyukov, Alexander A.,Vologzhanina, Anna V.,Es'kova, Marina A.,Shubina, Elena S.,Levitsky, Mikhail M.,Shul'pin, Georgiy B.
-
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- 2,3-Dichloro-5,6-dicyano-1,4-benzoquinone-catalyzed aerobic oxidation reactions via multistep electron transfers with iron(II) phthalocyanine as an electron-transfer mediator
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A new biomimetic catalytic oxidation system which employs 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) as the catalyst, molecular oxygen as the terminal oxidant and iron(ii) phthalocyanine (FeIIPc) as the electron-transfer mediator has been developed. This system can be applied for oxidative deprotection of PMB ethers, alcohol oxidation, aromatization and α,β-unsaturated aldehyde formation. After immobilizing FeIIPc on multi-walled carbon nanotubes, it can be reused without loss of activity.
- Hong, Yiming,Fang, Tiantian,Li, Meichao,Shen, Zhenlu,Hu, Xinquan,Mo, Weimin,Hu, Baoxiang,Sun, Nan,Jin, Liqun
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p. 51908 - 51913
(2016/06/13)
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- A removing the hydroxy group of a benzyl protecting group method (by machine translation)
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The invention discloses a process for the removal of the hydroxyl group of a method of a benzyl protecting group, the method is as follows: to the hydroxy compound by the hydroxy group with protection of the benzyl protecting group of the benzyl compound as reaction substrate, in order to 2, the 3 [...] two chloro -5,6 the [...] two cyanato -1, the 4 [...] benzoquinone (DDQ) and phthalocyanine ferrous (Fe II Pc) as catalyst, in order to 4,4 '-bipyridine (4, the 4 [...] -bpy) as an auxiliary agent, with oxygen as the oxidizing agent, in an organic solvent in the reaction substrate, the oxygen pressure 0.3-0.6 MPa, temperature 60-120 °C reaction is carried out under the condition of, removing the hydroxy group of a benzyl protecting group obtain hydroxyl compound. With the traditional use of chemical metering of oxidation with DDQ for the protection, the consumption of DDQ in this invention is greatly reduced, reducing the cost of reaction; with DDQ as catalyst, metal oxide or metal salt is compared with oxidation of the oxidizing agent for the protection, the used in the present invention oxygen as the oxidizing agent, reduces the environmental costs. (by machine translation)
- -
-
Paragraph 0029
(2016/11/07)
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- P-Tolylimido rhenium(v) complexes with phenolate-based ligands: Synthesis, X-ray studies and catalytic activity in oxidation with tert-butylhydroperoxide
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The reactions of mer-[Re(p-NTol)X3(PPh3)2] (X = Cl, Br) with chelating phenolate-based ligands (2-(2-hydroxy-5-methylphenyl)benzotriazole (HL1), 2-(2-hydroxyphenyl)benzothiazole (HL2) or 2-(2-hydroxyphenyl)benzoxazole (HL3)) afforded a series of p-tolylimido rhenium(v) complexes cis- or trans-(X,X)-[Re(p-NTol)X2(L)(PPh3)]·yMeCN (where X = Cl, Br; L = L1, L2, L3 and y = 0-2) and [Re(p-NTol)X(L)(PPh3)2]Z·pPPh3 (where X = Cl, Br; Z = ReO4, PF6; L = L1, L2, L3 and p = 0 or 1). The reported compounds were characterized by elemental analysis, FT-IR, NMR (1H, 13C and 31P) and X-ray crystallography. Interestingly, the halide ions of [Re(p-NTol)Cl2(L1)(PPh3)]·MeCN (1) and [Re(p-NTol)Cl2(L2)(PPh3)]·2MeCN (3) are in cis relative dispositions, whereas the complexes [Re(p-NTol)Br2(L)(PPh3)] (L1 for 2, L2 for 4 and L3 for 6) and [Re(p-NTol)Cl2(L3)(PPh3)] (5) were found to be trans-(X,X) isomers. The compounds [Re(p-NTol)X(L)(PPh3)2](PF6) (X = Cl, Br; L = L1 and L2) and [Re(p-NTol)X(L3)(PPh3)2](PF6)·PPh3 (X = Cl, Br) have been tested in oxidative catalysis. A few compounds exhibited very good catalytic properties in oxidation of alcohols with tert-BuOOH (TBHP) in acetonitrile solution at moderate temperatures. Complex [Re(p-NTol)Cl(L2)(PPh3)2]PF6 (13) is the catalyst of choice for oxidation of 1-phenylethanol to acetophenone (in 80% yield; turnover number attained 290 after 30 h) and cyclooctanol to cyclooctanone (in 88% yield). Notably lower activity has been found in the oxidation of alkanes with TBHP. Product distribution in the oxidation of methylcyclohexane indicates some steric hindrance around the reaction center.
- Gryca, Izabela,Machura, Barbara,Malecki, Jan Grzegorz,Kusz, Joachim,Shul'Pina, Lidia S.,Ikonnikov, Nikolay S.,Shul'Pin, Georgiy B.
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p. 334 - 351
(2015/12/26)
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- Oxidation of alkanes and benzene with hydrogen peroxide catalyzed by ferrocene in the presence of acids This article is dedicated to the memory of Aleksandr Evgenievich Shilov (1930-2014).
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The efficient (turnover numbers attained 1200) oxidation of alkanes to the corresponding alkyl hydroperoxides by H2O2 in the presence of catalytic amounts of ferrocene proceeds in MeCN at 40-50 °C. Benzene is oxidized in the same system to phenol. An obligatory component of the catalytic system for both reactions is pyrazine-2-carboxylic acid (PCA) or trifluoroacetic acid (TFA). Kinetic study as well as selectivity parameters testified that the oxidation proceeds with the participation of hydroxyl radicals. In the case of PCA as a co-catalyst the initial rate W0 of the reaction with both cyclohexane and benzene depends quadratically on [Cp2Fe]0 whereas the two reactions in the presence of TFA are of half order in ferrocene. The ferrocene-catalyzed reaction of cyclohexane with H2O216 in an atmosphere of labeled 18O2 gave after 2 h a mixture of labeled and unlabeled cyclohexyl hydroperoxide (total yield 20% based on starting cyclohexane) containing up to 69% of 18O (the analysis was after reduction of cyclohexyl hydroperoxide into cyclohexanol with PPh3).
- Shul'pina, Lidia S.,Kudinov, Aleksandr R.,Mandelli, Dalmo,Carvalho, Wagner A.,Kozlov, Yuriy N.,Vinogradov, Mikhail M.,Ikonnikov, Nikolay S.,Shul'pin, Georgiy B.
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p. 217 - 231
(2015/09/01)
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- Olefin cis-Dihydroxylation and Aliphatic C-H Bond Oxygenation by a Dioxygen-Derived Electrophilic Iron-Oxygen Oxidant
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Many iron-containing enzymes involve metal-oxygen oxidants to carry out O2-dependent transformation reactions. However, the selective oxidation of C-H and C-C bonds by biomimetic complexes using O2 remains a major challenge in bioinspired catalysis. The reactivity of iron-oxygen oxidants generated from an FeII-benzilate complex of a facial N3 ligand were thus investigated. The complex reacted with O2 to form a nucleophilic oxidant, whereas an electrophilic oxidant, intercepted by external substrates, was generated in the presence of a Lewis acid. Based on the mechanistic studies, a nucleophilic FeII-hydroperoxo species is proposed to form from the benzilate complex, which undergoes heterolytic O-O bond cleavage in the presence of a Lewis acid to generate an FeIV-oxo-hydroxo oxidant. The electrophilic iron-oxygen oxidant selectively oxidizes sulfides to sulfoxides, alkenes to cis-diols, and it hydroxylates the C-H bonds of alkanes, including that of cyclohexane. Lewis acid mediated O-O bond cleavage: A nucleophilic iron(II)-hydroperoxo oxidant, formed upon oxidative decarboxylation of an iron(II)-α-hydroxy acid complex, undergoes heterolytic O-O bond cleavage in the presence of a Lewis acid to generate an electrophilic iron(IV)-oxo-hydroxo oxidant. The electrophilic oxidant oxidizes sulfides to sulfoxides and alkenes to cis-diols, and it hydroxylates the strong C-H bonds of aliphatic substrates.
- Chatterjee, Sayanti,Paine, Tapan Kanti
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supporting information
p. 9338 - 9342
(2015/08/06)
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- Alkane oxidation with peroxides catalyzed by cage-like copper(II) silsesquioxanes
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Isomeric cage-like tetracopper(II) silsesquioxane complexes [(PhSiO1.5)12(CuO)4(NaO0.5)4] (1a), [(PhSiO1.5)6(CuO)4(NaO0.5)4(PhSiO1.5)6] (1b) and binuclear complex [(PhSiO1.5)10(CuO)2(NaO0.5)2] (2) have been studied by various methods. These compounds can be considered as models of some multinuclear copper-containing enzymes. Compounds 1a and 2 are good pre-catalysts for the alkane oxygenation with hydrogen peroxide in air in an acetonitrile solution. Thus, the 1a-catalyzed reaction with cyclohexane at 60°C gave mainly cyclohexyl hydroperoxide in 17% yield (turnover number, TON, was 190 after 230 min and initial turnover frequency, TOF, was 100 h-1). The alkyl hydroperoxide partly decomposes in the course of the reaction to afford the corresponding ketone and alcohol. The effective activation energy for the cyclohexane oxygenation catalyzed by compounds 1a and 2 is 16 ± 2 and 17 ± 2 kcal mol-1, respectively. Selectivity parameters measured in the oxidation of linear and branched alkanes and the kinetic analysis revealed that the oxidizing species in the reaction is the hydroxyl radical. The analysis of the dependence of the initial reaction rate on the initial concentration of cyclohexane led to a conclusion that hydroxyl radicals attack the cyclohexane molecules in proximity to the copper reaction centers. The oxidations of saturated hydrocarbons with tert-butylhydroperoxide (TBHP) catalyzed by complexes 1a and 2 exhibit unusual selectivity parameters which are due to the steric hindrance created by bulky silsesquioxane ligands surrounding copper reactive centers. Thus, the methylene groups in n-octane have different reactivities: the regioselectivity parameter for the oxidation with TBHP catalyzed by 1a is 1:10.5:8:7. Furthermore, in the oxidation of methylcyclohexane the position 2 relative to the methyl group of this substrate is noticeably less reactive than the corresponding positions 3 and 4. Finally, the oxidation of trans-1,2-dimethylcyclohexane with TBHP catalyzed by complexes 1a and 2 proceeds stereoselectively with the inversion of configuration. The 1a-catalyzed reaction of cyclohexane with H216O2 in an atmosphere of 18O2 gives cyclohexyl hydroperoxide containing up to 50% of 18O. The small amount of cyclohexanone, produced along with cyclohexyl hydroperoxide, is 18O-free and is generated apparently via a mechanism which does not include hydroxyl radicals and incorporation of molecular oxygen from the atmosphere.
- Vinogradov, Mikhail M.,Kozlov, Yuriy N.,Bilyachenko, Alexey N.,Nesterov, Dmytro S.,Shul'pina, Lidia S.,Zubavichus, Yan V.,Pombeiro, Armando J. L.,Levitsky, Mikhail M.,Yalymov, Alexey I.,Shul'pin, Georgiy B.
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supporting information
p. 187 - 199
(2015/02/19)
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- One-pot room-temperature conversion of cyclohexane to adipic acid by ozone and UV light
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Nitric acid oxidation of cyclohexane accounts for ～95% of the worldwide adipic acid production and is also responsible for ～5 to 8% of the annual worldwide anthropogenic emission of the ozone-depleting greenhouse gas nitrous oxide (N2O). Here we report a N2O-free process for adipic acid synthesis.Treatment of neat cyclohexane, cyclohexanol, or cyclohexanone with ozone at room temperature and 1 atmosphere of pressure affords adipic acid as a solid precipitate. Addition of acidic water or exposure to ultraviolet (UV) light irradiation (or a combination of both) dramatically enhances the oxidative conversion of cyclohexane to adipic acid.
- Hwang, Kuo Chu,Sagadevan, Arunachalam
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p. 1495 - 1498
(2015/02/19)
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- Cytochrome P450 catalyzed oxidative hydroxylation of achiral organic compounds with simultaneous creation of two chirality centers in a single C-H activation step
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Regio- and stereoselective oxidative hydroxylation of achiral or chiral organic compounds mediated by synthetic reagents, catalysts, or enzymes generally leads to the formation of one new chiral center that appears in the respective enantiomeric or diastereomeric alcohols. By contrast, when subjecting appropriate achiral compounds to this type of C-H activation, the simultaneous creation of two chiral centers with a defined relative and absolute configuration may result, provided that control of the regio-, diastereo-, and enantioselectivity is ensured. The present study demonstrates that such control is possible by using wild type or mutant forms of the monooxygenase cytochrome P450 BM3 as catalysts in the oxidative hydroxylation of methylcyclohexane and seven other monosubstituted cyclohexane derivatives.
- Roiban, Gheorghe-Doru,Agudo, Ruben,Reetz, Manfred T.
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supporting information
p. 8659 - 8663
(2014/08/18)
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- New p-tolylimido rhenium(v) complexes with carboxylate-based ligands: Synthesis, structures and their catalytic potential in oxidations with peroxides
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Novel p-tolylimido rhenium(v) complexes trans-(Cl,Cl)-[Re(p-NC 6H4CH3)Cl2(pyz-2-COO)(PPh 3)]·MeCN (1), trans-(Cl,Cl)-[Re(p-NC6H 4CH3)Cl2(pyz-2-COO)(PPh
- Gryca,MacHura,Malecki,Shul'Pina, Lidia S.,Pombeiro, Armando J. L.,Shul'Pin, Georgiy B.
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p. 5759 - 5776
(2014/04/03)
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- Selective oxidation of saturated hydrocarbons using Au-Pd alloy nanoparticles supported on metal-organic frameworks
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Gold (Au) and palladium (Pd) nanoparticles dispersed on a zeolite-type metal-organic framework (i.e., MIL-101) were prepared via a simple colloidal method. The catalysts were characterized by powder X-ray diffraction, N 2 physical adsorption, atomic absorption spectroscopy, transmission electron microscopy, energy-dispersive X-ray spectroscopy, and X-ray photoelectron spectroscopy. Au and Pd were mostly in the form of bimetallic alloys on the MIL-101 support. The Au-Pd/MIL-101 was active and selective in the oxidation of a variety of saturated (including primary, secondary, and tertiary) C-H bonds with molecular oxygen. For the liquid-phase oxidation of cyclohexane, cyclohexane conversion exceeding 40% was achieved (TOF: 19 000 h-1) with >80% selectivity to cyclohexanone and cyclohexanol under mild solvent-free conditions. Moreover, the Au-Pd alloy catalyst exhibited higher reactivity than their pure metal counterparts and an Au + Pd physical mixture. The high activity and selectivity of Au-Pd/MIL-101 in cyclohexane aerobic oxidation may be correlated to the synergistic alloying effect of bimetallic Au-Pd nanoparticles.
- Long, Jilan,Liu, Hongli,Wu, Shijian,Liao, Shijun,Li, Yingwei
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p. 647 - 654
(2013/05/21)
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- Copper-catalyzed aerobic oxidative functionalization of C-H bonds of alkanes in the presence of acetaldehyde under mild conditions
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Copper-catalyzed oxidative functionalization of C-H bonds of alkanes with molecular oxygen has been performed in the presence of Cu(OAc)2 catalyst and acetaldehyde in acetonitrile at 70 C with extremely high turn-over numbers.
- Hayashi, Yukiko,Komiya, Naruyoshi,Suzuki, Ken,Murahashi, Shun-Ichi
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p. 2706 - 2709
(2013/06/26)
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- Selective activation of secondary C-H bonds by an iron catalyst: Insights into possibilities created by the use of a carboxyl-containing bipyridine ligand
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In this work, we report the discovery of a carboxyl-containing iron catalyst 1 (FeII-DCBPY, DCBPY = 2,2′-bipyridine-4,4′- dicarboxylic acid), which could activate the C-H bonds of cycloalkanes with high secondary (2°) C-H bond selectivity. A turnover number (TN) of 11.8 and a 30% yield (based on the H2O2 oxidant) were achieved during the catalytic oxidation of cyclohexane by 1 under irradiation with visible light. For the transformation of cycloalkanes and bicyclic decalins with both 2° and tertiary (3°) C-H bonds, 1 always preferred to oxidise the 2° C-H bonds to the corresponding ketone and alcohol products; the 2°/3° ratio ranged between 78/22 and >99/1 across 7 examples. 18O isotope labelling experiments, ESR experiments, a PPh3 method and the catalase method were used to characterize the reaction process during the oxidation. The success of 1 showed that, in addition to using a bulky catalyst, high 2° C-H bond selectivity could also be achieved using a less bulky molecular iron complex as the catalyst.
- Cheng, Shi,Li, Jing,Yu, Xiaoxiao,Chen, Chuncheng,Ji, Hongwei,Ma, Wanhong,Zhao, Jincai
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p. 3267 - 3273
(2013/10/01)
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- Iridium-catalyzed aerobic oxidation of alkylarenes with excellent turnover numbers
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A highly efficient catalyst system has been developed for the aerobic oxidation of alkylarenes under solvent free conditions. The combination of iridium complex, nitrogen ligand and iodobenzene was found to be crucial for catalytic activity. Excellent turnover numbers were achieved for the preparation of benzoic acids and aryl ketones. This finding may provide useful clues for improving commercially important oxidation processes.
- Yan, Yunyun,Chen, Yanyan,Yan, Ming,Li, Xingshu,Zeng, Wei
-
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- Alkali metal directed assembly of heterometallic Vv/M (M = Na, K, Cs) coordination polymers: Structures, topological analysis, and oxidation catalytic properties
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The reactions of [VO(acac)2] with bis(salicylaldehyde)- oxaloyldihydrazone (H4L) and an alkali metal carbonate M 2CO3 (M = K, Na, Cs), in EtOH/H2O medium upon reflux, resulted in the generation of three new heterometallic VV/M materials, namely the 1D [(VO2)2(μ4-L) {Na2(μ-H2O)2(H2O) 2}]n (1), 2D [{V(μ-O)2}2(μ 4-L){K2(μ-H2O)2(H 2O)2}]n (2), and 3D [{V(μ-O) (μ3-O)}2(μ8-L){Cs2(μ-H 2O)2(H2O)2}]n (3) coordination polymers. They were isolated as air-stable solids and fully characterized by IR, UV-vis, 1H, and 51V NMR spectroscopy, ESI-MS(±), elemental, thermal, and single-crystal X-ray diffraction analyses, the latter showing that 1-3 are constructed from the resembling [(VO2)2(μ4/8-L)]2- blocks assembled by the differently bound aqua-metal [M2(μ-H 2O)2(H2O)2]2+ moieties (M = Na, K, Cs). The main distinctive features of 1-3 arise from the different coordination numbers of Na (5), K (7), and Cs (9) atoms, thus increasing the complexity of the resulting networks from the ladder-like 1D chains in 1 to double 2D layers in 2, and layer-pillared 3D framework in 3. The topological analysis of 2 disclosed a uninodal 4-connected underlying net with a rare kgm [Shubnikov plane net (3.6.3.6)/kagome pattern] topology, while 3 features a trinodal 4,7,8-connected underlying net with an unprecedented topology. Compounds 1-3 also show solubility in water (S25 C ≈ 4-7 mg mL-1) and were applied as efficient precatalysts for the homogeneous oxidation of cyclohexane by aqueous H2O2, under mild conditions (50 C) in MeCN/H2O medium and in the presence of an acid promoter. Total yields (based on substrate) of cyclohexanol and cyclohexanone up to 36% and turnover numbers (TONs) up to 5700 were achieved.
- Gupta, Samik,Kirillova, Marina V.,Guedes Da Silva, M. Fatima C.,Pombeiro, Armando J. L.,Kirillov, Alexander M.
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p. 8601 - 8611
(2013/09/02)
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- Highly efficient divanadium(V) pre-catalyst for mild oxidation of liquid and gaseous alkanes
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A new binuclear oxovanadium(V) complex bearing an NO2-donor Schiff base ligand, [{VO(EtO)(EtOH)}2(1κ2O,κN: 2κ2O,κN-L)]·2H2O (H4L = bis(2-hydroxybenzylidene)oxalohydrazonic acid) was prepared and fully characterized by IR, 1H NMR and electronic spectroscopies, elemental analysis and single crystal X-ray diffraction. In the presence of 2-pyrazinecarboxylic acid (PCA) or another acid promoter, this compound acts as a highly efficient pre-catalyst towards the oxidation of gaseous and liquid alkanes by aqueous H2O2 under mild conditions, in aqueous MeCN. Total yields of oxygenates up to 45% and overall turnover numbers up to 7.8 × 103 are achieved.
- Gupta, Samik,Kirillova, Marina V.,Guedes Da Silva, M. Fátima,Pombeiro, Armando J.L.
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- A new binuclear oxovanadium(v) complex as a catalyst in combination with pyrazinecarboxylic acid (PCA) for efficient alkane oxygenation by H 2O2
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A new binuclear oxovanadium(v) complex [{VO(OEt)(EtOH)}2L] (1) where H4L is bis(2-hydroxybenzylidene)terephthalohydrazide has been synthesized and fully characterized. The combination of 1 with pyrazine-2-carboxylic acid (PCA; a cocatalyst) affords a catalytic system for the efficient oxidation of saturated hydrocarbons, RH, with hydrogen peroxide and air in acetonitrile solution at 50°C to produce alkyl hydroperoxides, ROOH, as the main primary products. Very high turnover numbers (TONs) have been attained in this reaction: for example, after 2220 min, TON = 44 000 and initial TOF (turnover frequency) = 3300 h-1 per molecule of complex 1. The estimated activation energy of the cyclohexane oxygenation in the presence of 1/PCA is Ea = 16 ± 2 kcal mol-1. This value is identical to that obtained for the cyclohexane oxidation with H 2O2 catalyzed by the (n-Bu4N)[VO 3]/PCA combination (17 ± 2 kcal mol-1). The dependences of initial oxidation rates W0 on the initial concentrations of all components of the reaction mixture have been determined. Based on these kinetic data and on the regio- and bond-selectivity parameters measured in the oxidation of linear and branched alkanes a mechanism of the oxidation has been proposed which includes the generation of hydroxyl radicals in the crucial stage. The Royal Society of Chemistry.
- Sutradhar, Manas,Shvydkiy, Nikita V.,Guedes Da Silva, M. Fátima C.,Kirillova, Marina V.,Kozlov, Yuriy N.,Pombeiro, Armando J. L.,Shul'Pin, Georgiy B.
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p. 11791 - 11803
(2013/09/02)
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- Characterization of nickel(ii)-acylperoxo species relevant to catalytic alkane hydroxylation by nickel complex with mCPBA
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Nickel complexes with hydrotris(pyrazolyl)borate (= TpR) ligands catalyze alkane oxidation with organic peroxide meta-Cl-C6H 4C(O)OOH (= mCPBA). The electronic and steric hindrance properties of TpR affect the catalyses. The complex with an electron-withdrawing group containing a less-hindered ligand, that is, TpMe2,Br, exhibits higher alcohol selectivity. Higher selectivity for secondary over tertiary alcohols upon oxidation of methylcyclohexane indicates that the oxygen atom transfer reaction proceeds within the coordination sphere of the nickel centers. A reaction of the catalyst precursor, dinuclear nickel(ii)-bis(μ-hydroxo) complexes, with mCPBA yields the corresponding nickel(ii)-acylperoxo species, as have been characterized by spectroscopy. Thermal decomposition of the nickel(ii)-acylperoxo species in CH2Cl2 yields the corresponding nickel(ii)-chlorido complexes through Cl atom abstraction. Employment of the brominated ligand increases the thermal stability of the acylperoxo species. Kinetic isotope effects observed on decay of the nickel(ii)-acylperoxo species indicate concerted O-O breaking of the nickel-bound acylperoxide and H-abstraction from the solvent molecule.
- Hikichi, Shiro,Hanaue, Kento,Fujimura, Takako,Okuda, Hideho,Nakazawa, Jun,Ohzu, Yoshiko,Kobayashi, Chiho,Akita, Munetaka
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p. 3346 - 3356
(2013/08/15)
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- Structural characterization and oxidation reactivity of a nickel(II) acylperoxo complex
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The nickel(II)-acylperoxo complex [Ni(TpCF3Me) (κ2-mCPBA)] (1CF3Me) [TpCF3Me = hydrotris(3-trifluoromethyl-5-methylpyrazolyl)borate, mCPBA = m-chloroperbenzoate] was isolated and fully characterized. The electrophilic oxygenation ability of 1CF3Me toward sulfides and olefins was confirmed. The Michaelis-Menten-type behavior of thioanisole oxygenation indicates the existence of a pre-equilibrium of substrate association in the reaction. In addition, 1CF3Me retains H-atom abstraction ability for hydrocarbons with activated methylene C-H bonds (e.g., fluorene). The oxidations of styrenes and these readily oxidizable hydrocarbons follow second-order kinetics, first-order each with respect to 1CF3Me and substrate. The lack of clear acceleration in the decay of 1CF3Me in the presence of substrates with high C-H bond dissociation energies (e.g., cyclohexane) suggests that another reaction pathway contributes through the O-O-cleaved intermediate.
- Nakazawa, Jun,Terada, Shota,Yamada, Masaki,Hikichi, Shiro
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supporting information
p. 6010 - 6013
(2013/06/04)
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- Aerobic oxidative deprotection of benzyl-type ethers under atmospheric pressure catalyzed by 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ)/tert-butyl nitrite
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A facile and efficient protocol for the oxidative deprotection of benzyl-type ethers has been developed. The reaction was performed with catalytic amounts of 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) and tert-butyl nitrite (TBN) under atmospheric pressure of O2. Under the optimal reaction conditions, a variety of p-methoxybenzyl (PMB), p-phenylbenzyl (PPB), and benzyl (Bn) ethers can be deprotected to their corresponding alcohols in excellent conversions and selectivities.
- Shen, Zhenlu,Sheng, Lili,Zhang, Xiaochu,Mo, Weimin,Hu, Baoxiang,Sun, Nan,Hu, Xinquan
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p. 1579 - 1583
(2013/03/28)
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- Hydrocarbon oxygenation with Oxone catalyzed by complex [Mn 2L2O3]2+ (L=1,4,7-trimethyl-1,4,7- triazacyclononane) and oxalic acid
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Oxone (peroxysulphate) very efficiently oxidizes benzene to p-quinone (TON 1140) and alkanes to the corresponding alcohols and ketones (aldehydes) in aqueous acetonitrile 50 °C if catalytic amounts of complex [Mn 2L2O3]2+ (L=1,4,7-trimethyl-1,4,7- triazacyclononane) and oxalic acid are present in the solution. In contrast to the similar reaction with H2O2, the alkane oxidation with Oxone does not afford the corresponding alkyl hydroperoxides. Phenol was quantitatively oxidized to a mixture of p-quinone and pyrocatechol (9:1 ratio). Cyclohexanol gave cyclohexanone (TON 400). The proposed mechanism includes the formation of an oxidizing species containing the Mn(V)O fragment. A kinetic study demonstrated that an adduct of [Mn2L2O 3]2+ and oxalic acid is formed in the initial stage. This adduct reacts with Oxone to generate the oxidizing species.
- Shul'pin, Georgiy B.,Kozlov, Yuriy N.,Shul'Pina, Lidia S.,Pombeiro, Armando J.L.
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supporting information
p. 8589 - 8599
(2012/10/29)
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