- A nanohybrid self-assembled from exfoliated layered vanadium oxide nanosheets and Keggin Al13 for selective catalytic oxidation of alcohols
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A nanoscale hybrid material (V2O5-Al13) for highly efficient alcohol oxidation is synthesized through electrostatic self-assembly between oppositely charged Keggin Al13 polyoxocations and exfoliated V2O5 nanosheets. The analyses by X-ray diffraction, electron microscopy, X-ray photoelectron spectroscopy and structural consideration based on charge balance indicate that the Keggin Al13 ions could be sparsely distributed in the nanosheet galleries. The as-prepared catalyst successfully achieved high catalytic activity toward alcohols (96.8% sel.) with the oxygen molecule as an ideal oxidant under mild conditions. Also, the nanohybrid showed an outstanding adsorption capability for benzyl alcohol (773 mg g-1). In comparison to individual exfoliated V2O5 nanosheets and bulk V2O5, the V2O5-Al13 nanohybrid catalyst exhibited superior catalytic activity and selectivity under the same experimental conditions. The results highlight the outstanding functionality of the V2O5-Al13 nanohybrid as an efficient oxidation catalyst. A detailed study of its structure-activity relationship showed that the high performance of the V2O5-Al13 nanohybrid is attributed to the adsorption-catalysis synergistic effect between V2O5 and Al13
- Fu, Guoyuan,Li, Lei,Li, Shuying,Luo, Fang,Shi, Rui,Wang, Shuang,Zhang, Zhijuan,Zou, Xinyu
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- MnII and CuII complexes with arylhydrazones of active methylene compounds as effective heterogeneous catalysts for solvent- and additive-free microwave-assisted peroxidative oxidation of alcohols
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A one-pot template reaction of sodium 2-(2-(dicyanomethylene)hydrazinyl)benzenesulfonate (NaHL1) with water and manganese(ii) acetate tetrahydrate led to the mononuclear complex [Mn(H2O)6](HL1a)2·4H2O (1), where (HL1a)- = 2-(SO3-)C6H4(NH)NC(CN) (CONH2) is the carboxamide species derived from nucleophilic attack of water on a cyano group of (HL1)-. The copper tetramer [Cu4(H2O)10(1κN:κ2O:κO,2κN:κO-L2)2]·2H2O (2) was obtained from reaction of Cu(NO3)2·2.5H2O with sodium 5-(2-(4,4-dimethyl-2,6-dioxocyclohexylidene)hydrazinyl)-4-hydroxybenzene-1,3-disulfonate (Na2H2L2). Both complexes were characterized by elemental analysis, IR spectroscopy, ESI-MS and single crystal X-ray diffraction. They exhibit a high catalytic activity for the solvent- and additive-free microwave (MW) assisted oxidation of primary and secondary alcohols with tert-butylhydroperoxide, leading to yields of the oxidized products up to 85.5% and TOFs up to 1.90 × 103 h-1 after 1 h under low power (5-10 W) MW irradiation. Moreover, the heterogeneous catalysts are easily recovered and reused, at least for three consecutive cycles, maintaining 89% of the initial activity and a high selectivity.
- Mahmudov, Kamran T.,Sutradhar, Manas,Martins, Luísa M. D. R. S.,Guedes da Silva, M. Fátima C.,Ribera, Alice,Nunes, Ana V. M.,Gahramanova, Shahnaz I.,Marchetti, Fabio,Pombeiro, Armando J. L.
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- Synthesis, crystallization mechanism, and catalytic properties of titanium-rich TS-1 free of extraframework titanium species
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A new route to the synthesis of TS-1 has been developed using (NH 4)2CO3 as a crystallization-mediating agent. In this way, the framework Ti content can be significantly increased without forming extraframework Ti species. The prepared catalyst had a Si/Ti ratio as low as 34 in contrast to the ratio of 58 achieved with the methods A and B established by the Enichem group (Clerici, M. G.; Bellussi, G.; Romano, U. J. Catal. 1991, 129, 159) and Thangaraj and Sivasanker (Thangaraj, A.; Sivasanker, S. J. Chem. Soc., Chem. Commun. 1992, 123), respectively. The material contained less defect sites than the samples synthesized by the other two methods. As a result, it showed much higher activity for the oxidation of various organic substrates, such as linear alkanes/alkenes and alcohols, styrene, and benzene. The crystallization mechanism of TS-1 in the presence of (NH4) 2CO3 was studied by following the whole crystallization process with X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), thermogravimetry/differential thermal analysis (TG/DTA), inductively coupled plasma atomic emission spectrometry (ICP), Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), diffuse reflectance UV-vis spectroscopy, and 29Si MAS (magic-angle spinning) NMR spectroscopy techniques. It was shown that the presence of (NH 4)2CO3 not only drastically lowered down pH, slowing down the crystallization process and making the incorporation of Ti into the framework match well with nucleation and crystal growth, but also modified the crystallization mechanism. It seems that the solid-phase transformation mechanism predominated in the crystallization process initiated by dissociation, reorganization, and recoalescence of the solidified gel although a small amount of nongelatinated Ti shifted to the solid during the crystal growth period. In contrast, a typical homogeneous nucleation mechanism occurred in the method A system. Thus, although in the method A system most of Ti cations was inserted into the lattice after the crystallization was nearly completed, the inclusion of Ti started at the earlier nucleation period in the presence of (NH 4)2CO3. This is favorable for the incorporation of Ti into the framework, resulting in a more homogeneous distribution of Ti in the framework. Oxidation of 1-hexene and 2-hexanol over the samples collected during the whole crystallization process indicated that condensation of Ti-OH and Si-OH proceeded even after the crystallization was completed. This resulted in an increase in hydrophobicity and an overall improvement in microscopic character of Ti species and consequently a great increase in the catalytic activity with further progress of crystallization.
- Fan, Weibin,Duan, Ren-Guan,Yokoi, Toshiyuki,Wu, Peng,Kubota, Yoshihiro,Tatsumi, Takashi
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- Wacker oxidation of 1-hexene in 1-n-butyl-3-methylimidazolium hexafluorophosphate ([bmim][PF6]), supercritical (SC) CO2, and SC CO2/[bmim][PF6] mixed solvent
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Oxidation of 1-hexene by molecular oxygen is conducted in 1-n-butyl-3-methylimidazolium hexafluorophosphate [bmim][PF6], supercritical (SC) CO2, SC CO2/[bmim][PF6] mixed solvent, and in the absence of solvent. T
- Hou, Zhenshan,Han, Buxing,Gao, Liang,Jiang, Tao,Liu, Zhimin,Chang, Yanhong,Zhang, Xiaogang,He, Jun
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- Halogen-bonded tris(2,4-bis(trichloromethyl)-1,3,5-triazapentadienato)-M(iii) [M = Mn, Fe, Co] complexes and their catalytic activity in the peroxidative oxidation of 1-phenylethanol to acetophenone
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One-pot template condensation of CCl3CN with ammonia on a metal source [MnCl2·4H2O, FeCl3·6H2O or Co(CH3COO)2·4H2O] in DMSO led to the formation of tris{2,4-bis(trichloromethyl)-1,3,5-triazapentadienato}-M(iii) complexes, [M{NHC(CCl3)NC(CCl3)NH}3]·n(CH3)2SO [M = Mn, n = 1 (1); M = Fe, n = 2 (2); M = Co, n = 2 (3)], which were characterized using elemental analysis, and IR, ESI-MS and single-crystal X-ray analysis. The role of inter- and intramolecular non-covalent halogen and hydrogen bonds in the synthesis of 1-3 is discussed. It is shown that the crystal ionic radii of the metal ions [68.5 (Co) 3.155 (2) > 3.133 (1) ?]. Compounds 1-3 and the related di(triazapentadienato)-Cu(ii) complex [Cu{NHC(CCl3)NC(CCl3)NH}2]·2(CH3)2SO (4) act as catalyst precursors for the additive-free microwave (MW) assisted homogeneous oxidation of 1-phenylethanol with tert-butylhydroperoxide (TBHP), leading to the formation of acetophenone with yields up to 99% and TONs up to 5.0 × 103 after 1 h of low power (10 W) MW irradiation. This journal is
- Shixaliyev, Namiq Q.,Gurbanov, Atash V.,Maharramov, Abel M.,Mahmudov, Kamran T.,Kopylovich, Maximilian N.,Martins, Luísa M. D. R. S.,Muzalevskiy, Vasily M.,Nenajdenko, Valentine G.,Pombeiro, Armando J. L.
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- Hydroxylation of Benzene and Hexane by Oxygen and Hydrogen over Palladium-containing Titanium Silicalites
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Palladium-containing titanium silicalite zeolites catalyse the hydroxylation of benzene and hexane by O2-H2 under mild conditions to give phenol and hexanols, respectively.
- Tatsumi, T.,Yuasa, K.,Tominaga, H.
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- Solvent-Free Microwave-Assisted Peroxidative Oxidation of Alcohols Catalyzed by Iron(III)-TEMPO Catalytic Systems
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The iron(III) complexes [H(EtOH)][FeCl2(L)2] (1), [H2bipy]1/2[FeCl2(L)2].DMF (2) and [FeCl2(L)(2,2′-bipy)] (3) (L = 3-amino-2-pyrazinecarboxylate; H2bipy = doubly protonated 4,4′-bipyridine; 2,2′-bipy = 2,2′-bipyridine, DMF = dimethylformamide) have been synthesized and fully characterized by IR, elemental and single-crystal X-ray diffraction analyses, as well as by electrochemical methods. Complexes 1 and 2 have similar mononuclear structures containing different guest molecules (protonated ethanol for 1 and doubly protonated 4,4′-bipyridine for 2) in their lattices, whereas the complex 3 has one 3-amino-2-pyrazinecarboxylate and a 2,2′-bipyridine ligand. They show a high catalytic activity for the low power (10 W) solvent-free microwave assisted peroxidative oxidation of 1-phenylethanol, leading, in the presence of TEMPO, to quantitative yields of acetophenone [TOFs up to 8.1 × 103 h-1, (3)] after 1 h. Moreover, the catalysts are of easy recovery and reused, at least for four consecutive cycles, maintaining 83 % of the initial activity and concomitant rather high selectivity. Graphical Abstract: 3-Amino-2-pyrazinecarboxylic acid is used to synthesize three new iron(III) complexes which act as heterogeneous catalysts for the solvent-free microwave-assisted peroxidative oxidation of 1-phenylethanol. [InlineMediaObject not available: see fulltext.]
- Karmakar, Anirban,Martins,Guedes Da Silva, M. Fátima C.,Hazra, Susanta,Pombeiro, Armando J. L.
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- Toward optimizing the performance of homogeneous L-Au-X catalysts through appropriate matching of the ligand (L) and counterion (X-)
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The effects of the ligand (L) and counterion (X-) are considered the two most important factors in homogeneous gold catalysis, but a rational understanding of their synergy/antagonism is still lacking. In this work, we synthesized a set of 16 gold complexes of the type L-Au-X that differ as follows: (i) L = PPh3 (L1), P(tBu)3 (L2), tris(3,5-bis(trifluoromethyl)phenyl)phosphine (PArF, L3), and 1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene (NHC, L4), with the deliberate purpose of varying the electron withdrawing ability of the ligand, and (ii) X- = BF4-, OTf-, OTs-, and TFA-, which have various coordinating abilities, basicities, and hydrogen bond acceptor powers. All these catalysts were tested in two different model reactions: the cycloisomerization of N-(prop-2-ynyl)benzamide to 2-phenyl-5-vinylidene-2-oxazoline and the methoxylation of 3-hexyne. The main results are that the choice of the most efficient L-Au-X catalyst for a given process should not be made by evaluating the properties of L and X- alone, but rather based on their best combination. For NHC-Au-X, the noncoordinating and weakly basic anions (such as BF4- and OTf-) have been recognized as the best choice for the cycloisomerization of N-(prop-2-ynyl)benzamide. On the other side, the intermediate coordinating ability and basicity of OTs- provide the best compromise for achieving an efficient methoxylation of 3-hexyne. A completely different trend is found in the case of complexes bearing phosphanes: OTs- and TFA- have been found to accelerate the cycloisomerization of N-(prop-2-ynyl)benzamide, and BF4- and OTf- are suitable for the methoxylation of 3-hexyne. A possible explanation of the observed differences between phosphane and NHC ancillary ligands might be found in the higher affinity of the counterion (especially OTs-) for the gold fragment for phosphane instead of NHC.
- Biasiolo, Luca,Del Zotto, Alessandro,Zuccaccia, Daniele
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- Hydration of alkynes catalyzed by [Au(X)(L)(ppy)]X in the green solvent γ-valerolactone under acid-free conditions: The importance of the pre-equilibrium step
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[AuCl(NHC)(ppy)]Cl (1) and [AuCl(PPh3)(ppy)]OTf (2) complexes [ppy = 2-phenylpyridine, NHC = 1,3-bis(2,6-di-isopropylphenyl)-imidazol-2-ylidene] successfully catalyze the hydration of alkynes in γ-valerolactone (GVL), under acid-free conditions. The solution structure, reactivity, and catalytic properties of (1) and (2) were established by means of multinuclear NMR and computational (DFT) studies. Structural features of 1 during the catalysis, inferred by NMR spectroscopy, clearly indicate that complex 1 retains its square planar structure and no reduction to Au(i) and/or Au(0) nanoparticles was observed. The overall catalytic and kinetic investigations [kinetic isotopic effect (KIE), effect of acid additives, the order of reaction with respect to the catalyst, alkyne and nucleophile and the effect of the temperature] supported by computational results confirm that the pre-equilibrium step of the reaction mechanism is the RDS: water or counterion substitution by 3-hexyne in the first co-ordination sphere of Au(iii) is the key step of the whole process. The description of the mechanism of the hydration of 3-hexyne catalyzed by 1 here reported appears therefore to be of high significance because comprehensive mechanistic studies of the Au(iii)-catalyzed hydration reaction of the CC bond are scarce in the literature and generally lack experimental basis.
- Belanzoni, Paola,Belpassi, Leonardo,Del Zotto, Alessandro,Segato, Jacopo,Zuccaccia, Daniele
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- Synthesis of 3,5-Di-tert-butyl-1,2-dihydroxybenzene Derivatives and Their Effect on Free-Radical Oxidation of Hexane and Oxygen Activation Ability of Neutrophils
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C6-Substituted derivatives of 3,5-di-tert-butyl-1,2-dihydroxybenzene have been synthesized, and their effect on radiation-induced free-radical oxidation of n-hexane and production of reactive oxygen and chlorine forms in neutrophils have been studied. It has been shown the introduction of the phenylhydrazone and phenylazomethine groups significantly increases the antioxidant activity of pyrocatechol derivatives. For six compounds, the ability to prevent the development of oxidative stress due to hyperproduction of active oxygen intermediates and HOCl/OCl? in neutrophils has been revealed.
- Ksendzova,Ostrovskaya,Semenkova,Sorokin,Shishkanova,Shadyro
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- Unexpected anion effect in the alkoxylation of alkynes catalyzed by N-heterocyclic carbene (NHC) cationic gold complexes
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The intermolecular alkoxylation of alkynes is the oldest application of cationic gold(I) catalysts; however, no systematic experimental data about the role of the anion are available. In this contribution, the role of the anion in this catalytic reaction as promoted by a N-heterocyclic carbene-based gold catalyst, [(NHC)AuX] (X = BARF- BF4- , OTf- ,OTs-, TFA- , or OAc- ) is analyzed, through a combined experimental (NMR spectroscopy) and theoretical (DFT calculation) approach. The most important factor seems to be the ability to abstract the proton from the methanol during the nucleophilic attack, and such ability is related to the anion basicity. On the other hand, too high coordination power or basicity of the anion worsens the catalytic performance by preventing alkyne coordination or by forming too much free methoxide in solution, which poisons the catalyst. The intermediate coordinating power and basicity of the OTs- anion provides the best compromise to achieve efficient catalysis.
- Biasiolo, Luca,Trinchillo, Marina,Belanzoni, Paola,Belpassi, Leonardo,Busico, Vincenzo,Ciancaleoni, Gianluca,D'Amora, Angela,Macchioni, Alceo,Tarantelli, Francesco,Zuccaccia, Daniele
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- Synthesis of TS-1 zeolites from a polymer containing titanium and silicon
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The synthesis of TS-1 zeolites is regarded as a milestone in zeolite history, and it has led to the revolution of the green oxidation system of using H2O2as an oxidant, leaving only water as the byproduct. However, because of the highly hydrolyzable titanium source, the preparation of TS-1 requires complex synthesis conditions. Moreover, the difference in the hydrolysis rate between the silicon source and titanium source tends to increase the difficulty of titanium insertion into the framework, and it is easy to generate extra-framework Ti species during the synthesis. Here, a high-quality TS-1 zeolite with a large external surface area and free of extra-framework Ti species has been successfully synthesized by using a kind of novel polymer containing titanium and silicon. Due to the high hydrolysis resistance of the polymer reagent, a good matching of the hydrolysis rate between the silicon source and the titanium source is realized during crystallization, which facilitates the incorporation of titanium into the framework. Furthermore, the TS-1 zeolite exhibited excellent catalytic performance inn-hexane oxidation with hydrogen peroxide as the oxidant. This method of synthesizing zeolites from polymers is expected to be widely applied for the synthesis of other titanium-containing zeotype materials.
- Xing, Jiacheng,Yuan, Danhua,Liu, Hanbang,Tong, Yansi,Xu, Yunpeng,Liu, Zhongmin
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- Oxidovanadium complexes with tridentate aroylhydrazone as catalyst precursors for solvent-free microwave-assisted oxidation of alcohols
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Aroylhydrazone oxidovanadium compounds, viz. the oxidoethoxidovanadium(V) [VO(OEt)L] (1) (H2L = salicylaldehyde-2-hydroxybenzoylhydrazone), the salt like dioxidovanadium(V) (NH3CH2CH2OH)+[VO2L]- (2), the mixed-ligand oxidovanadium(V) [VO(hq)L] (Hhq = 8-hydroxyquinoline) (3) and the vanadium(IV) [VO(phen)L] (phen = 1,10-phenanthroline) (4) complexes (3 and 4 obtained by the first time), have been tested as catalysts for solvent-free microwave-assisted oxidation of aromatic and alicyclic secondary alcohols with tert-butylhydroperoxide. A facile, efficient and selective solvent-free synthesis of ketones was achieved with yields up to 99% (TON = 497, TOF = 993 h-1 for 3) and 58% (TON = 291, TOF = 581 h-1 for 2) for acetophenone and cyclohexanone, respectively, after 30 min under low power (25 W) microwave irradiation.
- Sutradhar, Manas,Martins, Luísa M.D.R.S.,Guedes da Silva, M. Fátima C.,Pombeiro, Armando J.L.
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- Chemoselective and Site-Selective Reductions Catalyzed by a Supramolecular Host and a Pyridine-Borane Cofactor
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Supramolecular catalysts emulate the mechanism of enzymes to achieve large rate accelerations and precise selectivity under mild and aqueous conditions. While significant strides have been made in the supramolecular host-promoted synthesis of small molecules, applications of this reactivity to chemoselective and site-selective modification of complex biomolecules remain virtually unexplored. We report here a supramolecular system where coencapsulation of pyridine-borane with a variety of molecules including enones, ketones, aldehydes, oximes, hydrazones, and imines effects efficient reductions under basic aqueous conditions. Upon subjecting unprotected lysine to the host-mediated reductive amination conditions, we observed excellent ?-selectivity, indicating that differential guest binding within the same molecule is possible without sacrificing reactivity. Inspired by the post-translational modification of complex biomolecules by enzymatic systems, we then applied this supramolecular reaction to the site-selective labeling of a single lysine residue in an 11-amino acid peptide chain and human insulin.
- Morimoto, Mariko,Cao, Wendy,Bergman, Robert G.,Raymond, Kenneth N.,Toste, F. Dean
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supporting information
p. 2108 - 2114
(2021/02/06)
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- Chromium-Catalyzed Production of Diols From Olefins
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Processes for converting an olefin reactant into a diol compound are disclosed, and these processes include the steps of contacting the olefin reactant and a supported chromium catalyst comprising chromium in a hexavalent oxidation state to reduce at least a portion of the supported chromium catalyst to form a reduced chromium catalyst, and hydrolyzing the reduced chromium catalyst to form a reaction product comprising the diol compound. While being contacted, the olefin reactant and the supported chromium catalyst can be irradiated with a light beam at a wavelength in the UV-visible spectrum. Optionally, these processes can further comprise a step of calcining at least a portion of the reduced chromium catalyst to regenerate the supported chromium catalyst.
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Paragraph 0111
(2021/03/19)
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- Expanding the Biocatalytic Toolbox with a New Type of ene/yne-Reductase from Cyclocybe aegerita
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This study introduces a new type of ene/yne-reductase from Cyclocybe aegerita with a broad substrate scope including aliphatic and aromatic alkenes/alkynes from which aliphatic C8-alkenones, C8-alkenals and aromatic nitroalkenes were the preferred substrates. By comparing alkenes and alkynes, a ~2-fold lower conversion towards alkynes was observed. Furthermore, it could be shown that the alkyne reduction proceeds via a slow reduction of the alkyne to the alkene followed by a rapid reduction to the corresponding alkane. An accumulation of the alkene was not observed. Moreover, a regioselective reduction of the double bond in α,β-position of α,β,γ,δ-unsaturated alkenals took place. This as well as the first biocatalytic reduction of different aliphatic and aromatic alkynes to alkanes underlines the novelty of this biocatalyst. Thus with this study on the new ene-reductase CaeEnR1, a promising substrate scope is disclosed that describes conceivably a broad occurrence of such reactions within the chemical landscape.
- Karrer, Dominik,Gand, Martin,Rühl, Martin
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p. 2191 - 2199
(2021/02/26)
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- Monoaurated: Vs. diaurated intermediates: Causality or independence?
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Diaurated intermediates of gold-catalysed reactions have been a long-standing subject of debate. Although diaurated complexes were regarded as a drain of active monoaurated intermediates in catalytic cycles, they were also identified as the products of gold-gold cooperation in dual-activation reactions. This study shows investigation of intermediates in water addition to alkynes catalysed by [(IPr)Au(CH3CN)(BF4)]. Electrospray ionisation mass spectrometry (ESI-MS) allowed us to detect both monoaurated and diaurated complexes in this reaction. Infrared photodissociation spectra of the trapped complexes show that the structure of the intermediates corresponds to α-gold ketone intermediates protonated or aurated at the oxygen atom. Delayed reactant labelling experiments provided the half life of the intermediates in reaction of 1-phenylpropyne (~7 min) and the kinetic isotope effects for hydrogen introduction to the carbon atom (KIE ~ 4-6) and for the protodeauration (KIE ~ 2). The results suggest that the ESI-MS detected monoaurated and diaurated complexes report on species with a very similar or the same kinetics in solution. Kinetic analysis of the overall reaction showed that the reaction rate is first-order dependent on the concentration of the gold catalyst. Finally, all results are consistent with the reaction mechanism proceeding via monoaurated neutral α-gold ketone intermediates only.
- Anania, Mariarosa,Ja?íková, Lucie,Zelenka, Jan,Shcherbachenko, Elena,Ja?ík, Juraj,Roithová, Jana
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p. 980 - 988
(2020/02/11)
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- Catalytic oxidation of primary c-h bonds in alkanes with bioinspired catalysts
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Catalytic oxidation of primary C-H bonds of alkanes with a series of iron and manganese catalysts is investigated. Products resulting from oxidation of methylenic sites are observed when hexane (S1) is used as model substrate, while corresponding primary C-H bonds remain unreactive. However, by using 2,2,3,3-tetra-methylbutane (S2) as model substrate, which only contains primary alkyl C-H bonds, oxidation takes place catalytically using a combination of hydrogen peroxide, a manganese catalyst and acetic acid as co-catalyst, albeit with modest yields (up to 4.4 TON). Complexes bearing tetradentate aminopyridine ligands provide the best yields, while a related pentadentate ligand provides smaller product yields. The chemoselectivity of the reaction is solvent dependent. Carboxylic acid 2b is observed as major product when the reaction takes place in acetonitrile, because of the facile overoxidation of the first formed alcohol product 2a. Instead the corresponding primary alcohol 2a becomes dominant in reactions performed in 2,2,2-trifluoroethanol (TFE). Polarity reversal of the hydroxyl moiety arising from the strong hydrogen bond donor ability of the latter solvent accounts for the unusual product chemoselectivity of the reaction. The significance of the current results in the context of light alkane oxidation is discussed.
- Dantignana, Valeria,Company, Anna,Costas, Miquel
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p. 470 - 477
(2020/09/09)
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- Efficient Palladium(0) supported on reduced graphene oxide for selective oxidation of olefins using graphene oxide as a ‘solid weak acid’
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Selective oxidation of olefin derivatives to ketones has made innovative development over palladium(0) supported on reduced graphene oxide. Compared to traditional Wacker oxidation, the novel method offers an economical and environment-friendly option by using graphene oxide (GO) as a ‘solid weak acid’ instead of classical homogeneous catalysts like H2SO4 and CF3COOH. X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscope and transmission electron microscopy images of Pd0/RGO showed that the nanoscaled Pd particles generated at the flake structure of reduced graphene oxide. Under optimized condition, up to 44 kinds of ketones with different structures can be prepared with excellent yields.
- Gao, Xi,Zhou, Jianhao,Peng, Xinhua
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- Synergistic hydrogen atom transfer with the active role of solvent: Preferred one-step aerobic oxidation of cyclohexane to adipic acid by N-hydroxyphthalimide
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In this work, we developed an one-step aerobic oxidation of cyclohexane to prepare adipic acid, catalyzed by N-hydroxyphthalimide (NHPI) under promoter- and metal-free conditions. A significant beneficial solvent effect for synergistic reaction is observed with varying polarity and hydrogen-bonding strength: detailed study reveals that the solvent environments manipulate catalytic activity and adipic acid selectivity. Cyclic voltammetry measurements and UV–visible spectra of the NHPI catalyst are examined in various solvent environments to understand the active role of solvent in influencing the catalytic-site structure (>NOH) of the molecule. Analysis of the UV–visible spectra reveals that these differences can be rationalized by considering hydrogen-bonding with solvent molecules, which modifies the catalytic-site structure. This observation is in agreement with cyclic voltammetry results: the different reversibility of the catalytic-site (>NOH/>NO[rad]) wave shows that the catalytic activity of NHPI is related to the formation of hydrogen bonds with the active participation of solvents. Computational studies presented herein have furnished mechanistic insights into the effect of solvent environments. Specifically, we present the structures, dissociation energies, and reaction barriers from DFT studies of the reactants and reaction intermediates involved in the two types of H-abstraction on >NO[rad] catalytic-sites for the rate-determining step. The results of modeling the solvent effects using the PCM continuum solvent method predict that the resulting reaction barrier of the rate-controlling H-abstraction for cyclohexane and cyclohexanone is modified significantly: the transition state barrier of H-abstraction for cyclohexane decreases from 22.36 (in benzene) to 20.78 kcal?mol?1 (in acetonitrile); the α-H-abstraction barrier for cyclohexanone decreases from 21.45 to 20.53 kcal?mol?1. The active participation of solvent molecule results in a strong interaction between pre-reaction complex (PINO???H???C NO[rad] catalytic-sites at the transition state. The lower calculated barriers of H-abstraction for cyclohexanone oxidation approximate more closely the experimental results of the higher adipic acid selectivity. Our work provides a dimension of sustainable chemistry for the metal-free preparation of adipic acid: a conversion of 27% with 79% adipic acid selectivity is achieved over use of NHPI catalysts in CH3CN solvent.
- Liang, Futong,Zhong, Wenzhou,Xiang, Liping,Mao, Liqiu,Xu, Qiong,Kirk, Steven Robert,Yin, Dulin
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p. 256 - 269
(2019/09/30)
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- Iron-catalyzed oxidative functionalization of C(sp3)-H bonds under bromide-synergized mild conditions
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An efficient oxidation and functionalization of C-H bonds with an inorganic-ligand supported iron catalyst and hydrogen peroxide to prepare the corresponding ketones was achieved using the bromide ion as a promoter. Preliminary mechanistic investigations indicated that the bromide ion can bind to FeMo6 to form a supramolecular species (FeMo6·2Br), which can effectively catalyze the reaction.
- Yu, Han,Zhao, Qixin,Wei, Zheyu,Wu, Zhikang,Li, Qi,Han, Sheng,Wei, Yongge
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supporting information
p. 7840 - 7843
(2019/07/12)
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- Selective Visible Light Aerobic Photocatalytic Oxygenation of Alkanes to the Corresponding Carbonyl Compounds
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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
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p. 8819 - 8824
(2019/09/30)
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- Atmospheric hydrogenation of Α Β-unsaturated ketones catalyzed by highly efficient and recyclable Pd nanocatalyst
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A thermoregulated phase-transfer Pd nanocatalyst was explored firstly and shown to be highly efficient and recyclable in the atmospheric hydrogenation of α β-unsaturated ketones. Under optimized reaction conditions, the conversion of chalcone and the selectivity of dihydrochalcone were 99% and 98%, respectively. The catalyst can be easily separated from the product and used directly for four times without evident loss in activity and selectivity. The turnover frequency (TOF) for the atmospheric hydrogenation of chalcone was 870 h?1, which to the best of our knowledge was the highest value ever reported among transition metal nanocatalysts.
- Chen, Pu,Li, Wenjiang,Wang, Yanhua
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- Methanol as hydrogen source: Chemoselective transfer hydrogenation of α,β-unsaturated ketones with a rhodacycle
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Methanol is a safe, economic and easy-to-handle hydrogen source. It has rarely been used in transfer hydrogenation reactions, however. We herein report that a cyclometalated rhodium complex, rhodacycle, catalyzes highly chemoselective hydrogenation of α,β-unsaturated ketones with methanol as the hydrogen source. A wide variety of chalcones, styryl methyl ketones and vinyl methyl ketones, including sterically demanding ones, were reduced to the saturated ketones in refluxing methanol in a short reaction time, with no need for inter gas protection, and no reduction of the carbonyl moieties was observed. The catalysis described provides a practically easy and operationally safe method for the reduction of olefinic bonds in α,β-unsaturated ketone compounds.
- Aboo, Ahmed H.,Begum, Robina,Zhao, Liangliang,Farooqi, Zahoor H.,Xiao, Jianliang
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p. 1795 - 1799
(2019/11/11)
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- Good isomerization of 2-cyclohexenol by two Ru(ii) complexes, synthesis and characterization of a reaction intermediate
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The catalytic activities of [RuClCp(PTA)2] (1) and [RuCp(PTA)2(H2O-κO)]OTf (2) were assessed for the redox isomerization of the cyclic allylic alcohol 2-cyclohexenol into cyclohexanone in water and biphasic media. Complex 2 showed unprecedented good TONs for the studied conversion both in water (TON = 647) and in the biphase of cyclohexene/H2O (TON = 3420) while 1 showed a lower but also good activity (water TON = 95, biphasic TON = 100). The catalytic reaction intermediate [RuCp(PTA)2(η2-C6H9OH)]CF3SO3 (3) was synthesized and characterized using NMR.
- Scalambra, Franco,López-Sanchez, Belen,Romerosa, Antonio
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supporting information
p. 16398 - 16402
(2018/12/05)
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- Variations on the Theme of JohnPhos Gold(I) Catalysts: Arsine and Carbene Complexes with Similar Architectures
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Arsine and carbene gold(I) complexes with architectures closely related to those of 2-(di-tert-butylphosphino)biphenyl gold(I) complexes have been prepared and structurally characterized. As predicted, 2-(di-tert-butylarsine)biphenyl gold(I) complexes are more electrophilic catalysts in comparison to their phosphine analogues, whereas those based on 4-arylindazole behave similarly to NHC-gold(I) catalysts.
- Carreras, Javier,Pereira, Ana,Zanini, Margherita,Echavarren, Antonio M.
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supporting information
p. 3588 - 3597
(2018/10/31)
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- Synthesis and characterization of Co3O4 immobilized on dipeptide-functionalized silica-coated magnetite nanoparticles as a catalyst for the selective aerobic oxidation of alcohols
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Synthesis and characterization of a new silica-coated magnetite nanocatalyst are described. This catalyst was prepared through a multistep procedure consisting of surface modification, functionalization with the product of an Ugi multicomponent reaction, and immobilization of Co3O4 on silica-coated magnetite nanoparticles. The prepared nanocatalyst was characterized using various techniques such as Fourier-transform infrared and energy-dispersive X-ray spectroscopies, thermal and elemental analyses, X-ray diffraction, and field-emission scanning and transmission electron microscopies. The catalyst showed high catalytic activity for the aerobic oxidation of alcohols in acetonitrile as the solvent at mild temperatures and reusability for five repeated runs without loss of its activity.
- Khodaei, Mohammad Mehdi,Dehghan, Mahsa
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p. 11381 - 11389
(2018/07/24)
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- Study on the degradation mechanism and pathway of benzene dye intermediate 4-methoxy-2-nitroaniline: Via multiple methods in Fenton oxidation process
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Benzene dye intermediate (BDI) 4-methoxy-2-nitroaniline (4M2NA) wastewater has caused significant environmental concern due to its strong toxicity and potential carcinogenic effects. Reports concerning the degradation of 4M2NA by advanced oxidation process are limited. In this study, 4M2NA degradation by Fenton oxidation has been studied to obtain more insights into the reaction mechanism involved in the oxidation of 4M2NA. Results showed that when the 4M2NA (100 mg L-1) was completely decomposed, the TOC removal efficiency was only 30.70-31.54%, suggesting that some by-products highly recalcitrant to the Fenton oxidation were produced. UV-Vis spectra analysis based on Gauss peak fitting, HPLC analysis combined with two-dimensional correlation spectroscopy and GC-MS detection were carried out to clarify the degradation mechanism and pathway of 4M2NA. A total of nineteen reaction intermediates were identified and two possible degradation pathways were illustrated. Theoretical TOC calculated based on the concentration of oxalic acid, acetic acid, formic acid, and 4M2NA in the degradation process was nearly 94.41-97.11% of the measured TOC, indicating that the oxalic acid, acetic acid and formic acid were the main products. Finally, the predominant degradation pathway was proposed. These results could provide significant information to better understand the degradation mechanism of 4M2NA.
- Guo, Ying,Xue, Qiang,Cui, Kangping,Zhang, Jia,Wang, Hui,Zhang, Huanzhen,Yuan, Fang,Chen, Honghan
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p. 10764 - 10775
(2018/03/26)
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- Hydration and alkoxylation of alkynes catalyzed by NHC-Au-OTf
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The NHC-Au-OTf [NHC = 1,3-bis(2,6-di-isopropylphenyl)-imidazol-2-ylidene] catalyst was tested in the alkoxylation and hydration of alkynes in a wide set of neoteric solvents for the first time. We found that most of these solvents (ethyl lactate, glycerol, propylene carbonate, d-limonene, γ-valerolactone, and p-cymene) are comparable or better solvents with respect to traditional VOSs. An important beneficial effect of γ-valerolactone was found in the hydration of inactive diphenylacetylene and one order of magnitude higher TOF was obtained with respect to the literature values. Kinetic experiments and DFT calculations seem to indicate that the polarity of the solvent and the presence of suitable proton acceptor/donor functionalities on the solvent itself could be taken into account.
- Gatto, Mattia,Baratta, Walter,Belanzoni, Paola,Belpassi, Leonardo,Del Zotto, Alessandro,Tarantelli, Francesco,Zuccaccia, Daniele
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supporting information
p. 2125 - 2134
(2018/05/24)
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- Hydration of Alkynes Catalyzed by L-Au-X under Solvent- and Acid-Free Conditions: New Insights into an Efficient, General, and Green Methodology
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L-Au-X [L = 1,3-bis(2,6-di-isopropylphenyl)-imidazol-2-ylidene {NHCiPr}, tris(3,5-bis(trifluoromethyl)phenyl)phosphine {PArF}, bis(imino)acenaphtene-1,3-bis(2,6-di-isopropylphenyl)dihydroimidazol-2-ylidene {BIAN}, 1,3-bis(2,6-di-isopropyl-phenyl)dihydroimidazol-2-ylidene {NHCCH2}, bis(tert-butylamino)methylidene {NAC}, 2-(di-tert-butylphosphino)biphenyl {JohnPhos}, tricyclohexylphosphine {PCy3}, triphenylphosphine {PPh3}, tris(2,4-di-tert-butylphenyl)phosphite {POR3}; X- = Cl-, OTf-, OTs-] catalysts were tested in the hydration of alkynes in neat and acid-free conditions. The overall catalytic evidence confirms that not only the counterion as previously observed by us but also the ligand play a crucial role. As a matter of fact, only complexes bearing NHC ligands showed appreciable catalytic activity. A complete rationalization of the ligand and counterion effects enabled us to develop a highly efficient methodology for the hydration of inactive diphenylacetylene in solvent-, silver-, and acid-free conditions. Thus, it was possible to reduce the catalyst loading to 0.01 mol % (with respect to diphenylacetylene) leading, to the best of our knowledge, to the highest TON (3400) and TOF (435 h-1) values found at 120 °C. The favorable catalytic conditions allowed us to reach for the first time very low E-factor (0.03) and high EMY (77) values for this substrate.
- Gatto, Mattia,Del Zotto, Alessandro,Segato, Jacopo,Zuccaccia, Daniele
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supporting information
p. 4685 - 4691
(2019/01/08)
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- Efficient Aliphatic C?H Bond Oxidation Catalyzed by Manganese Complexes with Hydrogen Peroxide
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A tetradentate nitrogen ligand containing a benzimidazole ring and an electron-rich pyridine ring was developed, the resulting manganese complex exhibited good activity in the C?H oxidation of simple alkanes. In particular, cyclic aliphatic alkanes were transformed into ketones in very good yields (up to 89 %) by using environmentally benign H2O2 as the terminal oxidant. This protocol was also applied successfully in benzylic C?H oxidation, giving the corresponding ketones with very good selectivities. In addition, tertiary C?H bond oxidation of complex molecules by the manganese complex showed potential utility for assembling alcohols with good selectivity in late-stage chemical synthesis.
- Wang, Wenfang,Xu, Daqian,Sun, Qiangsheng,Sun, Wei
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supporting information
p. 2458 - 2464
(2018/04/02)
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- Iron-Catalyzed Chemoselective Reduction of α,β-Unsaturated Ketones
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An iron-catalyzed chemo- and diastereoselective reduction of α,β-unsaturated ketones into the corresponding saturated ketones in mild reaction conditions is reported herein. DFT calculations and experimental work underline that transfer hydride reduction is a more facile process than hydrogenation, unveiling the fundamental role of the base.
- Lator, Alexis,Gaillard, Sylvain,Poater, Albert,Renaud, Jean-Luc
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supporting information
p. 5770 - 5774
(2018/03/26)
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- Hydrodeoxygenation of Sorbitol into Bio-Alkanes and -Alcohols Over Phosphated Ruthenium Molybdenum Catalysts
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Biofuels such as renewable alkanes and higher alcohols have drawn considerable interests for the use in internal combustion engines. Especially, higher alcohols could be used as a blending agent for diesel fuels. Herein, carbon supported phosphated ruthenium-molybdenum (RuMoP) catalysts were employed in continuous trickle-bed reactor for converting sorbitol into renewable alkanes and higher alcohols. The results showed that RuMoP on an active carbon (AC) support presented a complete sorbitol conversion and high yields of alkanes and alcohols in gasoline and diesel range. Subsequently, carbon nanotube (CNT) supported RuMoP was prepared and studied in detail for comparison. RuMoP/CNT presented a low C?C bond cracking property in sorbitol conversion and high selectivity of C6 products in gas-phase (C6 alkane, 74.7 %) and oil-phase (C6 alkane and alcohols, 87.8 %). Finally, detailed characterizations (N2-adsorption, XRD, HRTEM, XPS, NH3-TPD, Py-IR spectrums, etc.) were performed over relevant catalysts (RuMoP/C and RuMoP/CNT) for correlating their catalytic and physicochemical properties.
- Weng, Yujing,Wang, Tiejun,Wang, Chenguang,Liu, Qiying,Zhang, Yulong,Duan, Peigao,Wang, Longlong,Yin, Hongxing,Liu, Shijun,Ma, Longlong
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p. 5046 - 5052
(2018/10/26)
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- SYSTEMS AND METHODS FOR SYNTHESIS OF PHENOLICS AND KETONES
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Embodiments herein relate to apparatus and systems for phenolic and ketone synthesis and methods regarding the same. In an embodiment, a method of producing phenolics and ketones is included. The method can specifically include forming a reaction mixture comprising nanocrystalline cellulose (NCC) and water. The method can also include contacting the reaction mixture with a metal oxide catalyst at a temperature of 350 degrees Celsius or higher and a pressure of at least about 3200 psi to form a reaction product mixture. The reaction product mixture can include at least about 20 wt. % phenolics and at least about 10 wt. % ketones as a percentage of the total mass of nanocrystalline cellulose (NCC). Other embodiments are also included herein.
- -
-
Paragraph 0080-0088
(2018/11/21)
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- Biocatalytic Racemization Employing TeSADH: Substrate Scope and Organic Solvent Compatibility for Dynamic Kinetic Resolution
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Racemization in combination with a kinetic resolution is the base for a dynamic kinetic resolution (DKR). Biocatalytic racemization was successfully performed for a broad scope of sec-alcohols by employing a single alcohol dehydrogenase (ADH) variant from Thermoanaerobacter pseudoethanolicus (formerly T. ethanolicus; TeSADH W110A I86A C295A). The catalyst employed as a lyophilized whole cell preparation or cell free extract, which tolerated various non-water miscible organic solvents under micro-aqueous or two-phase conditions, whereby cyclohexane and n-hexane suited best. Various concepts for combining the enzymatic racemization with an enzymatic kinetic resolution to achieve overall a bis-enzymatic DKR were evaluated. A proof of concept showed a successful DKR with racemization in aqueous phase combined with acylation in the organic phase.
- Pop?oński, Jaros?aw,Reiter, Tamara,Kroutil, Wolfgang
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p. 763 - 768
(2018/02/27)
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- Mixed-valence μ3-oxo-centered triruthenium cluster [Ru3(II,III,III)(μ3-O)(μ-CH3CO2)6(H2O)3]·2H2O: Synthesis, structural characterization, valence-state delocalization and catalytic behavior
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The oxo-centered, trinuclear, mixed valence [Ru3(II,III,III)O(CH3CO2)6(H2O)3]·2H2O (2) acetate complex has been prepared with high yield through reduction of [Ru3(III,III,III)O(CH3CO2)6(CH3OH)3]·CH3CO2precursor compound in presence of muccic acid under hydrothermal conditions. The crystalline trinuclear oxo-cluster has been obtained as crystalline powder and characterized by single-crystal and powder X-ray diffraction, elemental analysis, SEM, TGA, IR spectroscopy. Complex 2 composes of μ3-oxocentered trinuclear ruthenium array and exhibits the oxidation state delocalization between three Ru atoms at 293 K. Accurate single-crystal analysis along with valence bond calculations reveal trapped-valence state delocalization at room temperature, whereas three-site relaxation occurs at 100 K leading to Ru(II) and Ru2(III) formal states. Moreover, the mixed valence of RuIIRu2IIIunit in compound 2 has been confirmed by XANES spectroscopy. The catalytic behavior of oxo-centered triruthenium complex 2 has been examined in hydration of nitriles and isomerization of allylic alcohols reactions both realized in aqueous media.
- Dikhtiarenko, Alla,Khainakov, Sergei,García, José R.,Gimeno, José
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p. 107 - 116
(2016/11/19)
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- Facile synthesis of [Ru(η2-O2CO)(pta)(η6-p-cymene)], an outstandingly active Ru(II) half-sandwich complex for redox isomerization of allylic alcohols
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The water-soluble [RuCl2(pta)(η6-p-cymene)] (pta = 1,3,5-triaza-7-phosphaadamantane) was applied as catalyst in the transposition of allylic alcohols, such as oct-1-en-3-ol in aqueous media. The isomerisation of oct-1-en-3-ol to octan-3-one took place only at pH > 10 buffer solutions or in the presence of alkali metal carbonates. The aqueous solution of “in situ” catalyst ([RuCl2(pta)(η6-p-cymene)] + 2 eq Na2CO3) could be reused in the biphasic isomerization of oct-1-en-3-ol for at least five times without a significant loss of the catalytic activity. It was demonstrated that carbonate is not only a base in this reaction but leads to formation of a highly active catalyst, [Ru(η2-O2CO)(pta)(η6-p-cymene)]. This compound was isolated as crystalline solid and characterized in detail (including X-ray diffraction).
- Bolyog-Nagy, Evelin,Udvardy, Antal,Barczáné-Bertók, ágnes,Joó, Ferenc,Kathó, ágnes
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p. 514 - 520
(2016/12/02)
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- Water and catalytic isomerization of linear allylic alcohols by [RuCp(H2O-κO)(PTA)2]+ (PTA = 1,3,5-triaza-7-phosphaadamantane)
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A new water soluble complex [RuCp(H2O-κO)(PTA)2]+ (1) (PTA = 1,3,5-triaza-7-phosphaadamantane) has been synthesized and fully characterized by NMR and IR. The crystal structure of 1(CF3SO3)·3.5H2O was characterized by single crystal X-ray determination. The catalytic activity of this complex was evaluated for the isomerisation of linear allylic alcohols from 3-buten-2-ol to 1-octen-3-ol into the correspondent ketones under both an inert atmosphere and in air, using as solvents: water, the substrate, mixtures of water/substrate, MeOH and mixtures of MeOH/water. An isomerization experiment on a mixture of all the studied allylic alcohols was also carried out.
- Scalambra, Franco,Serrano-Ruiz, Manuel,Romerosa, Antonio
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supporting information
p. 5864 - 5871
(2017/07/10)
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- Mononuclear Ruthenium and Osmium Complexes with a Bicyclic Guanidinate Ligand: Synthesis and Catalytic Behavior in Olefin Isomerization Processes
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The preparation of the first mononuclear RuII, RuIV, and OsII complexes containing the anion of the bicyclic guanidine 1,3,4,6,7,8-hexahydro-2H-pyrimido[1,2-a]pyrimidine (Hhpp) as a chelating ligand, namely [RuX{κ2-(N,N′)-hpp}(η6-arene)] [arene = p-cymene, X = Cl (2a), Br (2b), I (2c); arene = C6Me6, X = Cl (7)], [RuCl{κ2-(N,N′)-hpp}(η3:η3-C10H16)] (9; C10H16 = 2,7-dimethylocta-2,6-diene-1,8-diyl), and [OsCl{κ2-(N,N′)-hpp}(η6-p-cymene)] (11), is described. Compounds 2a–c, 7, 9, and 11 have been fully characterized by elemental analysis, HRMS, IR and NMR spectroscopy. In addition, the structure of 2a has been unequivocally confirmed by single-crystal X-ray diffraction methods. The catalytic behavior of these metal guanidinate complexes in the base-free redox isomerization of allylic alcohols is explored, with the ruthenium(IV) derivative 9 showing the best performance (TOF up to 5940 h–1). All of the synthesized complexes have also proven to be active in the isomerization of the allylbenzene estragole into the industrially relevant 1-propenylbenzene anethole, with a trans selectivity of up to 95 %.
- Gámez-Rivera, Sebastián A.,Francos, Javier,Borge, Javier,Cadierno, Victorio
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p. 4138 - 4146
(2017/09/28)
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- PROCESS FOR PRODUCTION OF KETONES FROM SECONDARY ALCOHOLS
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The present invention relates to the process for production of ketones from secondary alcohols by the use of a hybrid material, formed by the dichlorohydrotris(pyrazol-1-y1)methane iron (II) complex covalently bound to multi-walled carbon nanotubes functionalized with superficial carboxylate groups, as efficient and selective catalyst of peroxidative oxidation, microwave-assisted and without solvent addition.
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Page/Page column 12; 13
(2017/07/31)
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- Methods to produce fuels
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The present disclosure generally relates to the catalytic conversion of alcohols into hydrocarbon ketones suitable for use as fuels. More specifically, the present disclosure relates to the catalytic conversion of a mixture of isopropanol-butanol-ethanol (IBE) or acetone-butanol-ethanol (ABE), into ketones suitable for use as fuels. The ABE or IBE mixtures may be obtained from the fermentation of biomass or sugars.
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Page/Page column 43; 44
(2018/02/28)
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- Highly efficient and green oxidation of alkanes and alkylaromatics with hydrogen peroxide catalysed by silver and vanadyl on mesoporous silica-coated magnetite
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A heterogeneous catalyst (FeSi/Ag/VO) based on silver and vanadyl as active sites and mesoporous silica-coated nanospheres of magnetite (Fe3O4@m-SiO2) as support was successfully prepared by deposition of Ag nanoparticles and the covalent grafting of vanadyl(IV) acetylacetonate on Fe3O4@m-SiO2. The catalyst exhibited excellent activity for the oxidation of alkanes, benzene and alkylaromatics using green oxidant H2O2 and oxalic acid in acetonitrile at 60?°C.
- Nouri, Seyed Hadi,Hosseini-Monfared, Hassan
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- Evaluation of catalytic activity of [RuClCp(dmoPTA)(PPh3)](OSO2CF3) in the isomerization of allylic alcohols in water (dmoPTA = 3,7-dimethyl-1,3,7-triaza-5-phosphabicyclo[3.3.1]nonane)
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The catalytic activity of [RuClCp(HdmoPTA)(PPh3)](OSO2CF3) (1) and the dimeric complexes [RuClCp(PPh3)-μ-dmoPTA-1κP:2κ2N,N'-MCl2] (M = Ni (2), Co (3), Zn (4)) for the isomerization in water under Ar and ambient atmosphere of 1-octen-3-ol, 1-hepten-3-ol and 1-hexen-3-ol was investigated. A detailed study was devoted to the catalytic activity under Ar of 1 for the isomerization of 1-octen-3-ol.
- Mena-Cruz, Adrian,Serrano-Ruiz, Manuel,Lorenzo-Luis, Pablo,Romerosa, Antonio,Kathó, ágnes,Joó, Ferenc,Aguilera-Sáez, Luis Manuel
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- Non-plasmonic metal nanoparticles as visible light photocatalysts for the selective oxidation of aliphatic alcohols with molecular oxygen at near ambient conditions
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Nanoparticles (NPs) of Pd and Pt were used for the selective oxidation of aliphatic alcohols with molecular oxygen as an oxidant at near ambient temperatures under visible light irradiation. Distinct final products were obtained under identical reaction conditions, aliphatic esters formed over the Pd NPs while aldehydes formed over the Pt NPs. The reason for this different product selectivity is proven to be due to the much stronger interaction of Pd NPs with alcohol and aldehyde compared to Pt NPs. The photocatalytic activity is tuneable by light intensity or a moderate change in the reaction temperature.
- Tana, Tana,Guo, Xiao-Wei,Xiao, Qi,Huang, Yiming,Sarina, Sarina,Christopher, Phillip,Jia, Jianfeng,Wu, Haishun,Zhu, Huaiyong
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p. 11567 - 11570
(2016/10/03)
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- Selective Oxidation of Aliphatic Alcohols using Molecular Oxygen at Ambient Temperature: Mixed-Valence Vanadium Oxide Photocatalysts
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Here we report a class of photocatalysts: mixed-valence vanadium oxide particles grafted onto a variety of oxide supports. In these catalysts V6O13 species with mixed oxidation states (V4+ or V5+) are believed to be catalytically active sites. These catalysts successfully enable alcohol oxidation to selectively produce aldehydes and ketones using O2 as the oxidant. The catalytic process is driven by visible light irradiation at room temperature and, most importantly, progresses with negligible overoxidation. The catalysts can even selectively oxidize aliphatic alcohols, which are much more challenging to control in comparison to aromatic analogues. They can also be applied to the activation and oxidation of the otherwise stable C-H bonds of saturated aromatic hydrocarbons, such as toluene and xylene, under irradiation. Both experimental results and density functional theory (DFT) simulations suggest the formation of V6O13-alkoxide species as the initial step in the catalytic cycle. The V6O13-alkoxide then acts as the light harvester, being excited by light of wavelength shorter than 550 nm. Facile room-temperature C-H bond cleavage in the excited state V6O13-alkoxide in the presence of O2 leads to the carbonyl-containing products. These findings demonstrate an example of light-driven selective oxidation of diverse alcohols via in situ formation of photoresponsive V6O13-alkoxide species. This catalytic process is especially valuable for the synthesis of temperature-sensitive products and represents an alternative pathway to many conventional thermal oxidation reactions.
- Zavahir, Sifani,Xiao, Qi,Sarina, Sarina,Zhao, Jian,Bottle, Steven,Wellard, Mark,Jia, Jianfeng,Jing, Liqiang,Huang, Yiming,Blinco, James P.,Wu, Haishun,Zhu, Huai-Yong
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p. 3580 - 3588
(2016/07/06)
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- Nonheme iron complex-catalyzed efficient alcohol oxidation by t-BuOOH with N-hydroxyphthalimide (NHPI) as co-catalyst: Implication of high valent iron-oxo species
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Two iron catalysts ([Fe(bpc)Cl2][Et4N] (1a) and [Fe(Me2bpb)Cl2][Et3NH] (1b)) displayed efficient catalysis in oxidation of various alcohols to the corresponding carbonyl products using t-BuOOH as an oxidant in the presence of N-hydroxyphthalimide (NHPI) under mild conditions. 1a having an electron-withdrawing group showed a little better catalytic activity than that of 1b with an electron-donating group. The mechanistic studies through Hammett plot, deuterium isotope effect, and the use of 2-methyl-1-phenylprop-2-yl hydroperoxide (MPPH) as a mechanistic probe suggested that the reactive oxidants responsible for the alcohol oxidation possibly involved FeIV[Formula presented]), and phthalimide N-oxyl radical [Formula presented]. On the other hand, the presence of imidazole increased the heterolytic cleavage of Fe-OOR intermediate to form FeV[Formula presented] species and accelerated its [Formula presented] bond cleavage rate. In particular, the formation of FeV[Formula presented] intermediate via the heterolytic cleavage of Fe-OOR species in the presence of imidazole in the catalytic oxidation systems of nonheme iron complexes with t-BuOOH was substantialized, for the first time, to the best of our knowledge.
- Bae, Jeong Mi,Lee, Myoung Mi,Lee, Seul Ah,Lee, Sun Young,Bok, Kwon Hee,Kim, Jinheung,Kim, Cheal
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- Photooxygenation of alkanes by dioxygen with: P -benzoquinone derivatives with high quantum yields
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Alkanes were oxygenated by dioxygen with p-benzoquinone derivatives such as p-xyloquinone in alkanes which are used as solvents to yield the corresponding alkyl hydroperoxides, alcohols and ketones under visible light irradiation with high quantum yields (Φ = 1000, 1600%). The photooxygenation is started by hydrogen atom abstraction from alkanes by the triplet excited states of p-benzoquinone derivatives as revealed by laser-induced transient absorption spectral measurements.
- Ohkubo, Kei,Hirose, Kensaku,Fukuzumi, Shunichi
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p. 731 - 734
(2016/07/06)
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- Solvent-Free Photooxidation of Alkanes by Dioxygen with 2,3-Dichloro-5,6-dicyano-p-benzoquinone via Photoinduced Electron Transfer
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Photooxidation of alkanes by dioxygen occurred under visible light irradiation of 2,3-dichloro-5,6-dicyano-p-benzoquinone (DDQ) which acts as a super photooxidant. Solvent-free hydroxylation of cyclohexane and alkanes is initiated by electron transfer from alkanes to the singlet and triplet excited states of DDQ to afford the corresponding radical cations and DDQ??, as revealed by femtosecond laser-induced transient absorption measurements. Alkane radical cations readily deprotonate to produce alkyl radicals, which react with dioxygen to afford alkylperoxyl radicals. Alkylperoxyl radicals abstract hydrogen atoms from alkanes to yield alkyl hydroperoxides, accompanied by regeneration of alkyl radicals to constitute the radical chain reactions, so called autoxidation. The radical chain is terminated in the bimolecular reactions of alkylperoxyl radicals to yield the corresponding alcohols and ketones. DDQ??, produced by the photoinduced electron transfer from alkanes to the excited state of DDQ, disproportionates with protons to yield DDQH2.
- Ohkubo, Kei,Hirose, Kensaku,Fukuzumi, Shunichi
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supporting information
p. 2255 - 2259
(2016/08/30)
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- Catalytic conversion of sorbitol to gasoline-ranged products without external hydrogen over Pt-modified Ir-ReOx/SiO2
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Deoxygenation of sorbitol was carried out over a Pt-modified Ir-ReOx/SiO2 catalyst in biphasic solvent system (n-decane + H2O) without external hydrogen. Good yield of gasoline-ranged products was obtained including C5-C6 alkanes and C2-C6 mono-functionalized compounds such as ketones, alcohols, cyclic ethers and carboxylic acids. The Pt(3 wt%)-Ir-ReOx/SiO2 catalyst showed the best performance in the production of gasoline-ranged products. The maximum yield of gasoline-ranged products was 42%. The distribution of the products can be tuned by the addition of HZSM-5. The main products were C5-C6 alkanes with addition of HZSM-5 while the main products were C2-C6 mono-functionalized compounds without addition of HZSM-5. Characterizations such as TPR, XRD, TEM, XANES, EXAFS, CO adsorption were performed. The results demonstrated that the Pt-Ir-ReOx/SiO2 catalyst showed the structure of Pt-Ir alloy particles partially covered with ReOx species. The number of surface Pt atoms in Pt(3)-Ir-ReOx/SiO2 was larger than that of Pt/SiO2 or Pt-ReOx/SiO2 because of the small size of Pt-Ir alloy particles. The large number of surface Pt atoms and the synergetic effect of Pt, Ir and ReOx species make the catalyst efficiently generate hydrogen by aqueous phase reforming of sorbitol, and the generated hydrogen is consumed in the hydrogenolysis C-O bonds.
- Liu, Sibao,Okuyama, Yasuyo,Tamura, Masazumi,Nakagawa, Yoshinao,Imai, Akio,Tomishige, Keiichi
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p. 122 - 131
(2016/05/11)
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- Nitrogen, Phosphorus, and Sulfur Co-Doped Hollow Carbon Shell as Superior Metal-Free Catalyst for Selective Oxidation of Aromatic Alkanes
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Metal-free heteroatom-doped carbocatalysts with a high surface area are desirable for catalytic reactions. In this study, we found an efficient strategy to prepare nitrogen, phosphorus, and sulfur co-doped hollow carbon shells (denote as NPS-HCS) with a surface area of 1020 m2 g-1. Using a poly(cyclotriphosphazene-co-4,4′-sulfonyldiphenol) (PZS) shell as carbon source and N, P, S-doping source, and the ZIF-67 core as structural template as well as extra N-doping source, NPS-HCS were obtained with a high surface area and superhydrophilicity. All these features render the prepared NPS-HCS a superior metal-free carbocatalyst for the selective oxidation of aromatic alkanes in aqueous solution. This study provides a reliable and facile route to prepare doped carbocatalysts with enhanced catalytic properties.
- Yang, Shuliang,Peng, Li,Huang, Peipei,Wang, Xiaoshi,Sun, Yongbin,Cao, Changyan,Song, Weiguo
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supporting information
p. 4016 - 4020
(2016/03/19)
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- Mesoporous nitrogen-doped carbons with high nitrogen contents and ultrahigh surface areas: Synthesis and applications in catalysis
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The development of mesoporous nitrogen-doped carbons (NDCs) with high nitrogen contents and high surface areas from biomass is of significance for many applications, such as oxidation reaction catalysts, electrode materials and so on. Herein we report a simple route to prepare mesoporous NDCs via calcinating the mixture of biomass feedstocks (including glucose, cellulose and lignin) and melamine using eutectic salts of KCl and ZnCl2 as the porogen, and a series of mesoporous NDCs with nitrogen content up to 11.9% and BET specific surface area up to 1800 m2 g-1 were obtained. Served as metal-free catalysts for oxidation of hydrocarbons with tert-butyl hydroperoxide in aqueous phase, the mesoporous NDC with a N content of 11.4% showed the highest efficiency compared to the reported N-doped carbons. Moreover, the as-prepared NDCs were indicated to be an ideal support to immobilize noble nanoparticles (e.g., Pd, Rh, Ru, Pt), producing a series of NDC supported metal nanocatalysts with metal particle size of around 2 nm. This work opens up a new way to prepare mesoporous N-doped carbon materials with tailored properties.
- Ma, Zhishuang,Zhang, Hongye,Yang, Zhenzhen,Ji, Guipeng,Yu, Bo,Liu, Xinwei,Liu, Zhimin
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p. 1976 - 1982
(2016/04/19)
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- Readily Accessible Bulky Iron Catalysts exhibiting Site Selectivity in the Oxidation of Steroidal Substrates
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Bulky iron complexes are described that catalyze the site-selective oxidation of alkyl C-H bonds with hydrogen peroxide under mild conditions. Steric bulk at the iron center is introduced by appending trialkylsilyl groups at the meta-position of the pyridines in tetradentate aminopyridine ligands, and this effect translates into high product yields, an enhanced preferential oxidation of secondary over tertiary C-H bonds, and the ability to perform site-selective oxidation of methylenic sites in terpenoid and steroidal substrates. Unprecedented site selective oxidation at C6 and C12 methylenic sites in steroidal substrates is shown to be governed by the chirality of the catalysts.
- Font, David,Canta, Mercè,Milan, Michela,Cussó, Olaf,Ribas, Xavi,Klein Gebbink, Robertus J. M.,Costas, Miquel
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supporting information
p. 5776 - 5779
(2016/05/09)
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- Fungal mediated kinetic resolution of racemic acetates to (R)-alcohols using Fusarium proliferatum
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Fungal mediated kinetic resolution of seven acyclic/aromatic acetates was achieved using Fusarium proliferatum to furnish (R)-alcohols in high enantiomeric excess (>95%). The kinetic resolution was established as one-pot two-step de-esterification/oxidation biocatalytic process. Further, the preparative scale synthesis of (R)-(+)-1-phenylethanol was accomplished through de-esterification/oxidation of (±)-1-phenylethyl acetate using the whole cell of F. proliferatum NCIM 1105.
- Jadhav, Dipesh D.,Patil, Harshal S.,Chaya, Patil S.,Thulasiram, Hirekodathakallu V.
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p. 4563 - 4567
(2016/09/23)
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- Novel coordination polymers with (Pyrazolato)-based tectons: Catalytic activity in the peroxidative oxidation of alcohols and cyclohexane
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Coupling five rigid or flexible bis(pyrazolato)-based tectons with late transition metal ions allowed us to isolate 18 coordination polymers (CPs). As assessed by thermal analysis, all of them possess a remarkable thermal stability, their decomposition temperatures lying in the range of 340-500 °C. As demonstrated by N2 adsorption measurements at 77 K, their Langmuir specific surface areas span the rather vast range of 135-1758 m2/g, in agreement with the porous or dense polymeric architectures retrieved by powder X-ray diffraction structure solution methods. Two representative families of CPs, built up with either rigid or flexible spacers, were tested as catalysts in (i) the microwave-assisted solvent-free peroxidative oxidation of alcohols by t-BuOOH, and (ii) the peroxidative oxidation of cyclohexane to cyclohexanol and cyclohexanone by H2O2 in acetonitrile. Those CPs bearing the rigid spacer, concurrently possessing higher specific surface areas, are more active than the corresponding ones with the flexible spacer. Moreover, the two copper(I)-containing CPs investigated exhibit the highest efficiency in both reactions, leading selectively to a maximum product yield of 92% (and TON up to 1.5 × 103) in the oxidation of 1-phenylethanol and of 11% in the oxidation of cyclohexane, the latter value being higher than that granted by the current industrial process.
- Timokhin, Ivan,Pettinari, Claudio,Marchetti, Fabio,Pettinari, Riccardo,Condello, Francesca,Galli, Simona,Alegria, Elisabete C. B. A.,Martins, Luísa M.D.R.S.,Pombeiro, Armando J. L.
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p. 2303 - 2317
(2015/05/13)
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- Regioselective Isomerization of 2,3-Disubstituted Epoxides to Ketones: An Alternative to the Wacker Oxidation of Internal Alkenes
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We report an alternative pathway to the Wacker oxidation of internal olefins involving epoxidation of trans-alkenes followed by a mild and highly regioselective isomerization to give the major ketone isomers in 66-98% yield. Preliminary kinetics and isotope labeling studies suggest epoxide ring opening as the turnover limiting step in our proposed mechanism. A similar catalytic system was applied to the kinetic resolution of select trans-epoxides to give synthetically useful selectivity factors of 17-23 for benzyl-substituted substrates.
- Lamb, Jessica R.,Mulzer, Michael,Lapointe, Anne M.,Coates, Geoffrey W.
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supporting information
p. 15049 - 15054
(2015/12/08)
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- Non-redox metal ions can promote Wacker-type oxidations even better than copper(II): A new opportunity in catalyst design
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In Wacker oxidation and inspired Pd(ii)/Cu(ii)-catalyzed C-H activations, copper(ii) is believed to serve in re-oxidizing of Pd(0) in the catalytic cycle. Herein we report that non-redox metal ions like Sc(iii) can promote Wacker-type oxidations even better than Cu(ii); both Sc(iii) and Cu(ii) can greatly promote Pd(ii)-catalyzed olefin isomerization in which the redox properties of Cu(ii) are not essential, indicating that the Lewis acid properties of Cu(ii) can play a significant role in Pd(ii)-catalyzed C-H activations in addition to its redox properties. Characterization of catalysts using UV-Vis and NMR indicated that adding Sc(OTf)3 to the acetonitrile solution of Pd(OAc)2 generates a new Pd(ii)/Sc(iii) bimetallic complex having a diacetate bridge which serves as the key active species for Wacker-type oxidation and olefin isomerization. Linkage of trivalent Sc(iii) to the Pd(ii) species makes it more electron-deficient, thus facilitating the coordination of olefin to the Pd(ii) cation. Due to the improved electron transfer from olefin to the Pd(ii) cation, it benefits the nucleophilic attack of water on the olefinic double bond, leading to efficient olefin oxidation. The presence of excess Sc(iii) prevents the palladium(0) black formation, which has been rationalized by the formation of the Sc(iii)...H-Pd(ii) intermediate. This intermediate inhibits the reductive elimination of the H-Pd(ii) bond, and facilitates the oxygen insertion to form the HOO-Pd(ii) intermediate, and thus avoids the formation of the inactive palladium(0) black. The Lewis acid promoted Wacker-type oxidation and olefin isomerization demonstrated here may open up a new opportunity in catalyst design for versatile C-H activations.
- Qin, Shuhao,Dong, Lei,Chen, Zhuqi,Zhang, Sicheng,Yin, Guochuan
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p. 17508 - 17515
(2015/10/19)
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