- Synthesis of zeolite@metal-organic framework core-shell particles as bifunctional catalysts
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A zeolite@metal-organic framework (ZSM-5@UiO-66) core-shell composite has been synthesized for the first time by solvothermal growth of UiO-66 on the surface of ZSM-5 particles. The acidity from ZSM-5 and the basicity from the amine groups in UiO-66 obtai
- Zhu, Guanghui,Graver, Richard,Emdadi, Laleh,Liu, Baoyu,Choi, Kyu Yong,Liu, Dongxia
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- Aerobic oxidation of benzyl alcohol in methanol solutions over Au nanoparticles: Mg(OH)2 vs MgO as the support
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Magnesium oxide and magnesium hydroxide materials containing supported gold nanoparticles (NPs), Au/Mg(OH)2 and Au/MgO, were prepared from the commercial MgO through the deposition-precipitation (DP) method and characterized by XRD, XPS, HRTEM, FTIR spectroscopy and N2 adsorption techniques. It was found that the starting MgO support was fully transformed into the Mg(OH)2 phase during the DP procedure. A nearly complete dehydration of the magnesium hydroxide and formation of Au/MgO was achieved through the reductive treatment at 500 C, whereas the treatment at 350 C still resulted in the Au/Mg(OH)2 material. The FTIR analysis showed a much higher ability of the Au/MgO surface to adsorb both benzyl alcohol and benzaldehyde (ca. 10 and 3 times, respectively), as compared to Au/Mg(OH) 2. Probably for this reason, the Au/MgO catalyst exhibited ca. 50% higher catalytic activity in the aerobic oxidation/oxidative methoxylation of benzyl alcohol in the methanol solutions with respect to the amount of surface gold atoms as compared to the Au/Mg(OH)2 catalyst, in spite of a larger size of the Au NPs. In addition, the thermal treatment of the catalyst at 500 C to dehydrate the support allowed to suppress the undesired side reaction between benzyl alcohol and primarily formed benzaldehyde to give benzyl benzoate.
- Estrada, Miguel,Costa, Vinícius V.,Beloshapkin, Sergey,Fuentes, Sergio,Stoyanov, Evgenii,Gusevskaya, Elena V.,Simakov, Andrey
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- A versatile metal-organic framework for carbon dioxide capture and cooperative catalysis
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A multi-functional MOF PCN-124 was constructed from Cu paddlewheel motifs and a judiciously designed novel ligand bearing carboxylate, pyridine, and amide groups. PCN-124 exhibits selective adsorption of CO2 over CH 4 and excellent catalytic activity in a tandem one-pot deacetalization-Knoevenagel condensation reaction as a cooperative catalyst. The Royal Society of Chemistry 2012.
- Park, Jinhee,Li, Jian-Rong,Chen, Ying-Pin,Yu, Jiamei,Yakovenko, Andrey A.,Wang, Zhiyong U.,Sun, Lin-Bing,Balbuena, Perla B.,Zhou, Hong-Cai
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- Linear free-energy relationships in chromium(VI) oxidation of substituted benzylamines in nonaqueous media
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The kinetics of oxidation of 11 para- and meta-substituted benzylamines by imidazolium fluorochromate (IFC) in different organic solvent media has been investigated in the presence of p-toluenesulfonic acid (TsOH). The reaction was run under pseudo-first-
- Thirumoorthi,Bhuvaneshwari,Elango
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- Immobilized V-MIL-101 on modified Fe3O4 nanoparticles as heterogeneous catalyst for epoxidation of allyl alcohols and alkenes
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As a new heterogeneous catalyst, Fe3O4 nanoparticles were prepared and modified with sodium silicate and (3-aminopropyl) trimethoxysilane (APTMS) followed by complexation with V-MIL-101 and designated as Fe3O4@SiO2@APTMS@VMIL-101. It was characterized using FTIR, TEM, and VSM techniques. The Fe3O4@SiO2@APTMS@VMIL-101 was found to successfully catalyze the epoxidation of allyl alcohols and alkenes with tert-butylhydroperoxide (TBHP) in moderate to high yields. The epoxidation of trans-stilbene, norbornen, cyclooctene, geraniol, trans-2-hexene-1ol and 1-octene-3-ol with 100% selectivity is promising. Investigation of the stability and reusability of Fe3O4@SiO2@APTMS@V-MIL-101 revealed the heterogeneity character of the catalyst with no desorption during the course of epoxidation reactions. High yields, clean reactions, ease of catalyst separation and recyclability of the solid catalyst are some advantages of this method.
- Farzaneh, Faezeh,Sadeghi, Yasaman
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- Can Contemporary Density Functional Theory Predict Energy Spans in Molecular Catalysis Accurately Enough to Be Applicable for in Silico Catalyst Design? A Computational/Experimental Case Study for the Ruthenium-Catalyzed Hydrogenation of Olefins
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The catalytic hydrogenation of cyclohexene and 1-methylcyclohexene is investigated experimentally and by means of density functional theory (DFT) computations using novel ruthenium XantphosPh (4,5-bis(diphenylphosphino)-9,9-dimethylxanthene) and XantphosCy (4,5-bis(dicyclohexylphosphino)-9,9-dimethylxanthene) precatalysts [Ru(XantphosPh)(PhCO2)(Cl)] (1) and [Ru(XantphosCy)(PhCO2)(Cl)] (2), the synthesis, characterization, and crystal structures of which are reported. The intention of this work is to (i) understand the reaction mechanisms on the microscopic level and (ii) compare experimentally observed activation barriers with computed barriers. The Gibbs free activation energy ΔG? was obtained experimentally with precatalyst 1 from Eyring plots for the hydrogenation of cyclohexene (ΔG? = 17.2 ± 1.0 kcal/mol) and 1-methylcyclohexene (ΔG? = 18.8 ± 2.4 kcal/mol), while the Gibbs free activation energy ΔG? for the hydrogenation of cyclohexene with precatalyst 2 was determined to be 21.1 ± 2.3 kcal/mol. Plausible activation pathways and catalytic cycles were computed in the gas phase (M06-L/def2-SVP). A variety of popular density functionals (ωB97X-D, LC-ωPBE, CAM-B3LYP, B3LYP, B97-D3BJ, B3LYP-D3, BP86-D3, PBE0-D3, M06-L, MN12-L) were used to reoptimize the turnover determining states in the solvent phase (DF/def2-TZVP; IEF-PCM and/or SMD) to investigate how well the experimentally obtained activation barriers can be reproduced by the calculations. The density functionals B97-D3BJ, MN12-L, M06-L, B3LYP-D3, and CAM-B3LYP reproduce the experimentally observed activation barriers for both olefins very well with very small (0.1 kcal/mol) to moderate (3.0 kcal/mol) mean deviations from the experimental values indicating for the field of hydrogenation catalysis most of these functionals to be useful for in silico catalyst design prior to experimental work.
- Rohmann, Kai,H?lscher, Markus,Leitner, Walter
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- Selective benzylic oxidation of alkylaromatics over Cu/SBA-15 catalysts under solvent-free conditions
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With the purpose of benzylic oxidation of alkylaromatics into corresponding ketones selectively under solvent-free conditions, cheap, simple and versatile Cu/SBA-15 catalyst system with the Cu loading of 5, 10, 15 and 20% has been prepared by impregnating SBA-15 support. Among Cu/SBA-15 catalysts, 10%Cu/SBA-15 exhibited superior activity and selectivity.
- Neeli, Chinna Krishna Prasad,Narani, Anand,Marella, Ravi Kumar,Rama Rao, Kamaraju Seetha,Burri, David Raju
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- Synthesis, structural characterization and application of a 2D coordination polymer of Mn-terephthalate as a heterogeneous catalyst for olefin oxidation
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A metal-organic coordination polymer of [Mn3(1,4- benzenedicarboxylate)3(DMF)4] ([Mn3(BDC) 3(DMF)4]n) was synthesized and characterized by IR spectra, elemental analysis (CHN), thermal gravimetric analysis (TGA) and single crystal X-ray diffraction analysis. The structure of [Mn 3(BDC)3(DMF)4]n is a 2D-periodic framework based on Mn(II)-terephthalate secondary building units (SBUs). The catalytic oxidation of various olefins was effectively carried out with [Mn 3(BDC)3(DMF)4]n. Moreover, the influence of key reaction parameters, including the solvents, reaction temperatures and nature of oxidant were studied. The optimized conditions were achieved by TBHP as the efficient oxidant in 1,2-dichloroethane solvent at 75 C. Finally, this catalyst was used for four cycles efficiently without a significant loss of yield.
- Bagherzadeh, Mojtaba,Ashouri, Fatemeh,Crossed D Signakovi?, Marijana
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- A bifunctional approach towards the mild oxidation of organic halides: 2-dimethylamino-N,N-dimethylaniline N-oxide
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The titled reagent incorporates an oxygen-centred nucleophile and a basic moiety - in a suitably mutual orientation - in the same molecule. It oxidises various primary benzylic bromides to the corresponding aromatic aldehydes under relatively mild conditions (MeCN/rt-50°C/6-24 h) in high yields (83-97%), and is thus a useful alternative to the Kornblum procedure. (C) 2000 Elsevier Science Ltd.
- Chandrasekhar, Sosale,Sridhar, Malayalam
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- Weakly distorted 8-quinolinolato iron(III) complexes as effective catalysts for oxygenation of organic compounds by hydrogen peroxide
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This paper first discloses that two heteroleptic 8-quinolinolato iron(III) complexes (Qa1Qb2FeIII, Qa2Qb1FeIII) could be synthesized conveniently via the coordination of FeCl2·6H2O with 2 equivalents of 5,7-dichloro-8-hydroxyquinoline (Qb) or 5-chloro-8-hydroxyquinoline (Qa) under N2 and then 1 equivalent of Qa or Qb under air. In comparison with the two homoleptic counterparts (Qa3FeIII and Qb3FeIII), the proposed heteroleptic Q3FeIII complexes possessed similar coordination features to the Qb3FeIII one but showed similar catalysis performances to the Qa3FeIII one in the oxygenation of cyclohexane to cyclohexanol and cyclohexanone by hydrogen peroxide (H2O2) in acetonitrile. More importantly, both heteroleptic Q3FeIII complexes showed a better accelerating effect on this reaction and provided a slightly higher conversion than the Qa3FeIII and especially Qb3FeIII ones. Furthermore, this predominance in catalytic activity was more strikingly apparent upon both-catalyzed oxygenations of benzene, toluene, ethylbenzene or thioanisole by H2O2. This should be due to a structurally distorted effect of the heteroleptic Q3FeIII complexes that is induced by the different in ligand environment, as supported by DFT B3LYP/6-311G (d) calculation. Based the present reaction and UV-vis spectral characterization results, a free radical mechanism for the present catalysis system was proposed.
- Wang, Yongjun,Wen, Xu,Rong, Chunying,Tang, Senpei,Wu, Wenfeng,Zhang, Chao,Liu, Yachun,Fu, Zaihui
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- Visible-light mediated C-C bond cleavage of 1,2-diols to carbonyls by cerium-photocatalysis
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We describe a photocatalytic method for the cleavage of vicinal diols to aldehydes and ketones. The reaction is catalyzed by blue light and a cerium-catalyst and the scope includes aryl as well as alkyl substituted diols. The simple protocol which works under air and at room temperature enables the valorization of abundant diols.
- Schwarz, Johanna,K?nig, Burkhard
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- Synthesis, characterisation and catalytic activities of manganese(III) complexes of pyridoxal-based ONNO donor tetradenatate ligands
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Reaction of MnII(CH3COO)2 with dibasic tetradentate ligands, N,N′-ethylenebis(pyridoxylideneiminato) (H 2pydx-en, I), N,N′-propylenebis(pyridoxylideneiminato) (H 2pydx-1,3-pn, II) and 1-methyl-N,N′- ethylenebis(pyridoxylideneiminato) (H2pydx-1,2-pn, III) followed by aerial oxidation in the presence of LiCl gives complexes [MnIII(pydx- en)Cl(H2O)] (1) [MnIII(pydx-1,3-pn)Cl(CH3OH)] (2) and [MnIII(pydx-1,2-pn)Cl(H2O)] (3), respectively. Crystal and molecular structures of [Mn(pydx-en)Cl(H2O)] (1) and [Mn(pydx-1,3-pn)Cl(CH3OH)] (2) confirm their octahedral geometry and the coordination of ligands through ONNO(2-) form. Reaction of manganese(II)-exchanged zeolite-Y with these ligands in refluxing methanol followed by aerial oxidation in the presence of NaCl leads to the formation of the corresponding zeolite-Y encapsulated complexes, abbreviated herein as [MnIII(pydx-en)]-Y (4), [MnIII(pydx-1,3-pn)]-Y (5) and [MnIII(pydx-1,2-pn)]-Y (6). These encapsulated complexes are used as catalysts for the oxidation, by H2O2, of methyl phenyl sulfide, styrene and benzoin efficiently. Oxidation of methyl phenyl sulfide under the optimized reaction conditions gave ca. 86% conversion with two major products methyl phenyl sulfoxide and methyl phenyl sulfone in the ca. 70% and 30% selectivity, respectively. Oxidation of styrene catalyzed by these complexes gave at least five products namely styrene oxide, benzaldehyde, benzoic acid, 1-phenylethane-1,2-diol and phenylacetaldehyde with a maximum of 76.9% conversion of styrene by 4, 76.3% by 5 and 76.0% by 6 under optimized conditions. The selectivity of the obtained products followed the order: benzaldehyde > benzoic acid > styrene oxide > phenylacetaldehyde > 1-phenylethane-1,2-diol. Similarly, ca. 93% conversion of benzoin was obtained by these catalysts, where the selectivity of the products followed the order benzil > benzoic acid > benzaldehyde-dimethylacetal. Tests for the recyclability and heterogeneity of the reactions have also been carried. Neat complexes are equally active. However, the recycle ability of encapsulated complexes makes them better over neat ones.
- Maurya, Mannar R.,Saini, Priyanka,Haldar, Chanchal,Avecilla, Fernando
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- Silica chromate as an oxidising agent for the chemoselective oxidation of alcohols and the oxidative deprotection of trimethylsilyl ethers
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Silica chromate easily converts primary and secondary alcohols to corresponding carbonyl compounds in the presence of wet SiO2 both in dichloromethane and under solvent-free conditions at room temperature with good to excellent yields. Primary and secondary trimethylsilyl ethers were converted into the corresponding carbonyl compounds or alcohols by using silica chromate and wet SiO2 in dichloromethane at room temperature with good to excellent yields.
- Zolfigol, Mohammad A.,Shirini, Farhad,Mohammadpoor-Baltork, Iraj,Choghamarani, Arash Gh.,Hajjami, Maryam,Sedaghat, Abdol M.
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- Utilizing Benign Oxidants for Selective Aerobic Oxidations Using Heterogenized Platinum Nanoparticle Catalysts
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By using platinum nanoparticle catalysts that are generated in situ by extrusion from a porous copper chlorophosphate framework, the role of oxidants in the selective oxidation of benzyl alcohol to benzaldehyde was evaluated, with a view to establishing s
- Hinde, Christopher S.,Gill, Arran M.,Wells, Peter P.,Hor, T. S. Andy,Raja, Robert
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- HETEROGENEOUS PHOTOCATALYTIC OXIDATION OF AROMATIC COMPOUNDS ON SEMICONDUCTOR MATERIALS: THE PHOTO-FENTON REACTION
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Heterogeneous photocatalytic oxidation of aromatic compounds by H2O2 formed from dissolved O2 in the presence of illuminated TiO2 powders was investigated with reference to the Fenton reaction.All the products expected from the Fenton reaction were obtained.The effect of other semiconductor materials and Fe(2+) on the reaction was also investigated.
- Fujihira, Masamichi,Satoh, Yoshiharu,Osa, Tetsuo
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- Mn(III) complexes with tridentate N,N,O-ligands as catalysts for the epoxidation of alkenes
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Mn(III) complexes with tridentate Schiff bases have been prepared and applied as catalyst precursors in epoxidation of alkenes using iodosobenzene as an oxidant providing high conversions and high selectivities when cyclohexene derivatives were studied.
- Aghmiz,Mostfa,Iksi,Rivas,Gonzalez,Diaz,El Guemmout,El Laghdach,Echarri,Masdeu-Bulto
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- Highly ordered mesoporous zirconia-polyoxometalate nanocomposite materials for catalytic oxidation of alkenes
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A series of well-ordered mesoporous ZrO2-based heteropoly acid nanocomposite frameworks has been prepared through a surfactant-assisted sol-gel copolymerization route. The pore walls of these materials consist of nanocrystalline tetragonal ZrO2 and Keggin-type 12-phosphomolybdic acid (PMA) components with different PMA loadings, i.e. 12, 22 and 37 wt%. Small angle X-ray scattering, high-resolution TEM and N2 physisorption measurements indicated mesoporous property in hexagonal p6mm symmetry with large internal BET surface areas and narrow-sized pores. The incorporated PMA clusters preserve intact their Keggin structure into the mesoporous frameworks according to EDX, FT-IR and diffuse-reflectance UV/vis/NIR spectroscopy. The obtained ZrO2-PMA nanocomposites demonstrated great application potential in oxidative catalysis, exhibiting exceptional stability and catalytic activity in oxidation of alkenes using hydrogen peroxide as oxidant. The Royal Society of Chemistry 2011.
- Armatas, Gerasimos S.,Bilis, Georgios,Louloudi, Maria
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- Oxidation of styrene oxide via chemical and photochemical methods using TiO2-CeO2-V2O5 catalysts
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This work reports the preparation of the TiO2-CeO2 (TiCe) catalytic support of V2O5 catalysts, which was tested in the oxidation process of styrene oxide via chemical and photochemical methods. The TiCe-V2O5 catalytic support was prepared by the co-precipitated method from the individual metal oxides, varying the amount of vanadium oxide by 3, 6, and 10 % mol with respect to the support. The obtained catalysts were characterized by different spectroscopies, as well as by the N2 adsorption-desorption technique. The catalytic reaction test was carried out in the liquid phase during 120 min with/without ultraviolet light irradiation at 50 °C. There was no V2O5 effect on the surface area, pore volume, and pore diameter since all catalysts had similar textural values. In all samples the structures identified by X-ray diffraction were the Anatase phase and CeO2 in the cubic phase. XPS results revealed the formation of surface carbonate species, which were also identified by infrared spectroscopy. The conversion rate was better when employing ultraviolet light, and the rate increased as the V2O5 amount rose. The main reaction products were 2-phenylethanol and 1-phenylethanol. However, a low amount of benzaldehyde was detected. The selectivity to the desirable product (2-phenylethanol) increased when the reaction was irradiated with UV light and the catalyst contained a higher amount of vanadium. It was observed that the effect of UV radiation on the electric mobility produces an acceleration of the reaction to 2-phenylethanol, avoiding the 1-phenylethanol formation. The bandgap value decreased as the vanadium oxide amount increased, boosting the electric mobility.
- Castro, Laura V.,Manríquez, Ma. Elena,Ortiz-Islas, Emma,Pliego, Andrea Sánchez,Valdez, Martín Trejo
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- Cobalt(III)-Catalyzed Functionalization of Unstrained Carbon-Carbon Bonds through β-Carbon Cleavage of Alcohols
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We demonstrate that a simple Co(III)-complex can efficiently catalyze the cleavage of unstrained C-C bonds via the β-carbon elimination of secondary and tertiary alcohols bearing a directing group. The cobalt-aryl intermediate generated under the reaction conditions can be trapped by different electrophiles to generate a new carbon-carbon bond. Some essential features of this new Co-based mechanistic manifold were revealed by preliminary mechanistic studies.
- Ozkal, Erhan,Cacherat, Bastien,Morandi, Bill
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- Direct synthesis of carbonyl compounds from THP ethers with IBX in the presence of β-cyclodextrin in water
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Water, an environmentally friendly reaction medium, has been utilized for the oxidative deprotection of tetrahydropyranyl ethers 1 with IBX at room temperature in the presence of β-cyclodextrin to give the corresponding carbonyl compounds 2.
- Narender,Reddy, M. Somi,Kumar, V. Pavan,Nageswar,Rao, K. Rama
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- An investigation of two copper(ii) complexes with a triazole derivative as a ligand: magnetic and catalytic properties
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Two new copper(ii) complexes [Cu2(L)2(OAc)2(H2O)2] (1) (L = 3-methyl-5-pyridin-2-yl-1,2,4-triazole) and [CuL2] (2) were prerared and thoroughly studied. The complexes are able to selectivel
- Doroshchuk, Roman O.,Gumienna-Kontecka, Elzbieta,Khomenko, Dmytro M.,Lampeka, Rostyslav D.,Martins, Luísa M. D. R. S.,Novitchi, Ghénadie,Petrenko, Yuliia P.,Piasta, Karolina,Shova, Sergiu,Toporivska, Yuliya
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- RHODIUM(II) ACETATE: AN EFFECTIVE HOMOGENEOUS CATALYST FOR SELECTIVE ALLYLIC OXIDATION AND CARBON-CARBON BOND FISSION OF OLEFINS
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Treatment of some cyclic olefins and allylbenzene with Rh2(OAc)4 in acetic acid in the presence of t-BuOOH gave the corresponding enones and allylic acetates, the former being predominant, Application to several styrene derivatives resulted in a selective C=C bond fission to give benzaldehyde or acetophenone.It is suggested that the reaction proceeds catalytically with Rh(II) acetate via an ionic pathway.
- Uemura, Sakae,Patil, Suresh R.
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- Disulfide-Catalyzed Visible-Light-Mediated Oxidative Cleavage of C=C Bonds and Evidence of an Olefin–Disulfide Charge-Transfer Complex
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A photocatalytic method for the aerobic oxidative cleavage of C=C bonds has been developed. Electron-rich aromatic disulfides were employed as photocatalyst. Upon visible-light irradiation, typical mono- and multi-substituted aromatic olefins could be converted into ketones and aldehydes at ambient temperature. Experimental and computational studies suggest that a disulfide–olefin charge-transfer complex is possibly responsible for the unconventional dissociation of S?S bond under visible light.
- Deng, Yuchao,Wei, Xiao-Jing,Wang, Hui,Sun, Yuhan,No?l, Timothy,Wang, Xiao
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- Oxidative deprotection of cyclic acetals and trimethylsilyl ethers by γ-picolinium chlorochromate under nonaqueous conditions
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Deprotection of cyclic acetals and oxidative desilylation of trimethylsilyl ethers into the corresponding carbonyl compounds with γ-picolinium chlorochromate (γ-PCC) under nonaqueous conditions at room temperature is described. Oxidation of aldehydes to carboxylic acids was not observed in any case.
- Salehi,Khodaei,Goodarzi
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- Nitrogen kinetic isotope effects for the monoamine oxidase B-catalyzed oxidation of benzylamine and (1,1-2H2)benzylamine: Nitrogen rehybridization and CH bond cleavage are not concerted
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Nitrogen kinetic isotope effects for the oxidation of benzylamine and (1,1-2H2)benzylamine by recombinant human monoamine oxidase B show that cleavage of the CH bond is not concerted with rehybridization of the nitrogen atom.
- MacMillar, Susanna,Edmondson, Dale E.,Matsson, Olle
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- A Ruthenium Heteropolyanion as Catalyst for Alkane and Alkene Oxidation
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A ruthenium heteropolyanion, SiRu(H2O)W11O395-, has been synthesized which catalyses the liquid phase oxidation of alkanes and alkenes with various primary oxidants including potassium persulphate, sodium periodate, t-butyl hydroperoxide, and iodosylbenzene; the activity and selectivity with the oxidant used.
- Neumann, Ronny,Abu-Gnim, Chalil
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- Copper-Functionalized Metal–Organic Framework as Catalyst for Oxidant-Controlled Partial Oxidation of Cyclohexene
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Microwave irradiation is exploited for the facile, one-step functionalization of Cu(acac)2 to –NH2 pendant groups of MIL-53(Al)-NH2, a metal–organic framework material, under mild reaction conditions and a short reaction time. PXRD, XPS, XAS, and EPR spectroscopy are used to investigate the structure and chemical nature of the copper species on the framework. The copper center exists in the +2 oxidation state with a square-planar geometry and NO3 coordination environment. The copper complex is anchored to the framework by imine bond formation. This copper-functionalized MIL-53(Al)-NH2 or MIL-53[Cu] is employed in the catalytic oxidation of olefins using molecular oxygen (O2) or tert-butyl hydroperoxide (TBHP) as the oxidant. The chemoselectivities of the oxidation products depend on the type of oxidant and substrate. When O2 is used as the oxidant and isobutyraldehyde as the co-oxidant in the oxidation of cyclohexene with MIL-53[Cu], cyclohexene oxide is the major product. However, when TBHP is employed as the oxidant, 2-cyclohexen-1-one is the major product. Furthermore, the catalyst can be reused at least three times without a significant loss in activity.
- Chotmongkolsap, Pannapat,Bunchuay, Thanthapatra,Klysubun, Wantana,Tantirungrotechai, Jonggol
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- Potassium iodide-catalyzed three-component synthesis of 2-arylquinazolines via amination of benzylic C-H bonds of methylarenes
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A novel potassium iodide-catalyzed three-component synthesis of quinazolines via benzylic C-H bonds amination was developed. Commonly used ammonia salt and the sp3 carbon in commercially available methylarenes were used as nitrogen and C1 sources, respectively. Mechanistic studies indicated that an aryl aldehyde is involved as a key intermediate in the reaction.
- Zhao, Dan,Shen, Qi,Li, Jian-Xin
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- Photochemical Electron-Transfer Reactions between Sulfides and Tetranitromethane. Oxidation vs Fragmentation of the Sulfide Radical-Cation Intermediate
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Oxidation and/or fragmentation products are observed in the photochemical reaction of the alkyl phenyl sulfides 1a-d with tetranitromethane (TNM). The product distribution depends markedly on the substrate structure. Thus, methyl phenyl sulfide (1a) and benzyl phenyl sulfide (1b) give only the corresponding sulfoxides (oxidation). However, when the radical cation 1b?+ is generated by chemical oxidation with triarylaminium salts (Ar3N?+) in acetonitrile, in addition to oxidation fragmentation is also observed, and with an excess of Ar3N?+ oxidation is facilitated and no fragmentation is produced. For the photoreaction of diphenylmethyl phenyl sulfide (1c) with TNM, fragmentation is the main reaction, while for triphenylmethyl phenyl sulfide (1d) only this process is observed. The ease of C-S bond scission in these sulfur-centered radical cations 1.+ follows the ease of alkyl cation formation, i.e., Ph3C > Ph2CH > PhCH2 > CH3.
- Adam, Waldemar,Argueello, Juan E.,Penenory, Alicia B.
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- Efficient selective oxidation of alcohols to carbonyl compounds catalyzed by Ru-terpyridine complexes with molecular oxygen
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The oxidation of alcohols with molecular oxygen is a promising approach to produce corresponding carbonyl compounds. In this work, efficient aerobic oxidation of alcohols to carbonyl compounds catalyzed by ruthenium-terpyridine [(tpy-PhCH3)RuCl3] with isobutyraldehyde as co-substrate was developed. Various alcohols including primary and secondary alcohols are smoothly converted to corresponding carbonyl compounds in good yield. In a 100 times large-scale oxidation of benzyl alcohol, benzaldehyde was obtained with 92% isolated yield. Moreover, a plausible mechanism involving high-valence ruthenium species was proposed based on in situ UV–vis spectroscopy.
- Han, Qi,Guo, Xiao-Xuan,Zhou, Xian-Tai,Ji, Hong-Bing
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- Selective activation of C-H bonds on the ring of ethylbenzene catalyzed by several diperoxovanadate complexes
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The competitive oxidation of the C-H bonds on the aromatic ring and side-chain of ethylbenzene (EB) with hydrogen peroxide is investigated over four diperoxovanadate catalysts, that is, K3[VO(O2) 2(ox)] (bpV(ox)), K2
- Liu, Qiuyuan,Zhu, Liangfang,Li, Li,Guo, Bin,Hu, Xiaoke,Hu, Changwei
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- Reusable catalysts based on dendrimers trapped in poly(p-xylylene) nanotubes
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Catalysts in a bottle are readily prepared by coelectrospinning of PAMAM dendrimers and polyethylene oxide) (PEO). The nanofibers thus obtained can be coated with poly(p-xylylene) by chemical vapor deposition. Removal of the core PEO fibers by extraction
- Lindner, Jean-Pierre,Roben, Caren,Studer, Armido,Stasiak, Michael,Ronge, Ramona,Greiner, Andreas,Wendorff, Hans-Joachim
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- Double-helical ruthenium complexes of 2,2′:6′,2″,2?:6?,2″″-quinquepyridine (qpy) for multi-electron oxidation reactions
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Double-helical ruthenium complexes of 2,′:6′,2″:6″,2?:6?,2″″- quinquepyridine (qpy) are prepared from RuCl3·xH2O and qpy and the crystal structure of [Ru2(qPy)2(C2O4)][CF 3SOsub
- Ho, Paul Kwok-Keung,Cheung, Kung-Kai,Che, Chi-Ming
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- Cucurbituril-mediated supramolecular acid catalysis
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The rates of acid hydrolysis of N-benzoyl-cadaverine (1), mono-N-(tert-butoxy)carbonyl cadaverine (2), and benzaldoxime (3) with binding motifs for cucurbit[6]uril (1,2) and cucurbit[7]uril (1,3) were investigated in the absence and presence of these hosts. Significant rate enhancements (up to a factor of ca. 300 for the hydrolysis of 3) were observed. Competitive inhibition due to encapsulation of added cadaverine and the successful use of sub-stoichiometric amounts of macrocycle confirmed the function of cucurbiturils in promoting acid hydrolysis.
- Kloeck, Cornelius,Dsouza, Roy N.,Nau, Werner M.
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- Synergistic catalysis within TEMPO-functionalized periodic mesoporous organosilica with bridge imidazolium groups in the aerobic oxidation of alcohols
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Anchoring 2,2,6,6-tetramethylpiperidine-1-oxyl radical (TEMPO) within the nanospaces of a periodic mesoporous organosilica with bridged imidazolium groups led to an unprecedented powerful bifunctional catalyst (TEMPO@PMO-IL-Br), which showed enhanced activity in the metal-free aerobic oxidation of alcohols. The catalyst and its precursors were characterized by N2 adsorption-desorption analysis, transmission electron microscopy (TEM), small angle X-ray scattering (SAXS), thermal gravimetric analysis (TGA), diffuse reflectance infrared Fourier transform spectroscopy (DRIFT), solid state electron paramagnetic resonance (EPR) spectroscopy, elemental analysis, transmission electron microscopy (TEM) and high resolution TEM. It was clearly found that the catalytic activity of SBA-15-functionalized TEMPO (TEMPO@SBA-15) not bearing IL, TEMPO@PMO-IL-Cl, PMO-IL-AMP, or individual catalytic functionalities (PMO-IL/TEMPO@SBA-15) was inferior as compared with those obtained from TEMPO@PMO-IL-Br in the metal-free aerobic oxidation of benzyl alcohol, suggesting the critical role of co-supported TEMPO and imidazolium bromide in obtaining high catalytic activity in the described catalyst system. Our observation clearly points to the fact that the combination of imidazolium bromide units in close proximity to TEMPO moieties in the nanospaces of TEMPO@PMO-IL-Br might be indeed one of the key factors explaining the enhanced catalytic activity observed for this catalyst in the oxidation of benzyl alcohol, possibly through a synergistic catalysis relay pathway. A proposed model was suggested for the observed synergistic effect.
- Karimi, Babak,Vahdati, Saleh,Vali, Hojatollah
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- Facile cleavage reactions of styrylic olefins using electrochemical methods
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Negative constant current electrolysis of styrylic olefins in an aqueous solvent resulted in the oxidative cleavage of the double bonds, giving carbonyl compounds in good yields. The double bond conjugated with more than one aromatic ring was selectively cleaved.
- Maki, Shojiro,Niwa, Haruki,Hirano, Takashi
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- Triplet State and Photodecarboxylation of Phenylglyoxylic Acid in the Presence of Water
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The photodecarboxylation of phenylglyoxylic acid (PA) was studied by quantum yield (Φd) and time-resolved conductivity measurements in polar solvents at room temperature. Φd is substantial (>/=0.3) in the presence of 3-30 M water in acetonitrile and at pH a = 1.1 in neat water.The triplet states of PA, of its ethyl ester, and of 4-carboxybenzaldehyde were observed by nanosecond laser flash photolysis and emission spectroscopy.The initial transient obtained from PA (e.g., in acetonitrile λmax = 322 nm; lifetime >/= 3 μs) is assigned to the n,?* triplet state, and a second transient (in 2-propanol; λmax = 313 nm; t1/2 > 100 μs) is assigned to the Ph-COH-COOH radical.Phosphorescence was observed in glassy matrices at -196 deg C and in acetonitrile, acetone, and acetic acid at 25 deg C.In the latter ("inert") solvents the phosphorescence intensity and the triplet lifetime (up to 20 μs) are reduced by addition of alcohols or water.The rate constant of H-atom abstraction by triplet PA from 2-propanol is 1.5 * 106 M-1 s-1 in acetonitrile.Addition of water to PA in the "inert" solvents results in a non-Stern-Volmer behavior for triplet quenching.Excitation of PA in neat aqueous solution yields the triplet of benzaldehyde, the excited photoproduct, as main transient whereas triplet PA could not be detected.A mechanism accounting for the dependences of Φd on the pH and on the H2O concentration in mixtures with acetonitrile is proposed.Water governs the photochemistry of PA in three respects, via the acid-base equilibrium, as triplet quencher, and by reducing the quantum yield of intersystem crossing to the anion triplet.
- Kuhn, Hans Jochen,Goerner, Helmut
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- Encapsulation of a double-helical water-nitrate chain inside unique double helical chiral channels formed from Keggin POM and hexaquo-cobalt(II) units
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A new inorganic-organic hybrid chiral molecule [Co(H2O) 6][C5H6N]H4[CoW12O 40]NO3·3H2O has been prepared by the hydrothermal method and was characterized by elemental analysis, IR and UV spectra, TG-DTA and single crystal X-ray diffraction techniques. The asymmetric unit consists of [CoW12O40]6- and NO 3- anions, the charge of which are counterbalanced by one octahedral [Co(H2O)6]2+ cation, a pyridinium [C5H6N]+ ion and 4H+ ions. The molecular structure of the title complex reveals a 3D supramolecular framework formed through intermolecular hydrogen bonds. This constitutes the first example in which a chiral architecture has been generated from achiral building blocks, where centrosymmetrically related cobalt octahedra and polyoxoanion tetrahedra are entangled through pairs of hydrogen bonds in a double helical way with a channel that houses a 1D water-NO3- double helix. This chiral POM shows good efficiency in the oxidation of common olefins in the presence of an environmentally benign oxidant, H2O2, under mild conditions.
- Chatterjee, Rajarshi,Paul, Luna,Hazra, Dipak K.,Pal, Nabanita,Jana, Atish Dipankar,Mukherjee, Monika,Ali, Mahammad
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- A green and efficient oxidation of benzylic alcohols using H2O2 catalyzed by Montmorillonite-K10 supported MnCl2
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Primary and secondary benzylic alcohols were oxidized to the corresponding carbonyl compounds in good to high yields by environmentally friendly and green oxidant, H2O2 catalyzed by Montmorillonite-K10 supported manganese(II) chlorid
- Najafi, Gholam Reza
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- A nanoscale iron catalyst for heterogeneous direct: N - And C -alkylations of anilines and ketones using alcohols under hydrogen autotransfer conditions
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Here, we report a commercially available nanoscale Fe catalyst for heterogeneous direct N- and C-alkylation reactions of anilines and methyl ketones with alcohols. A hydrogen autotransfer mechanism has been found to operate in these reactions by deuterium labelling studies. In addition, dehydrogenative quinoline synthesis has been demonstrated from amino benzyl alcohols and acetophenones.
- Nallagangula, Madhu,Sujatha, Chandragiri,Bhat, Venugopal T.,Namitharan, Kayambu
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- Synthesis, structural characterization, and catalytic reactivity of a new molybdenum(VI) complex containing 1,3,4-thiadiazole derivative as a tridentate NNO donor ligand
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A new cis-dioxo molybdenum(VI) complex was obtained by reaction of 2,4-dihydroxybenzylidene(5-N,N-methylphenylamino-1,3,4-thiadiazol-2-yl)hydrazone as ligand and [MoO2(acac)2] in methanol and was characterized by elemental analyses,
- Moradi-Shoeili, Zeinab,Zare, Maryam,Bagherzadeh, Mojtaba,Kubicki, MacIej,Boghaei, Davar M.
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- Functionalized-1,3,4-oxadiazole ligands for the ruthenium-catalyzed Lemieux-Johnson type oxidation of olefins and alkynes in water
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Three arene-ruthenium(II) complexes bearing alkyloxy(5-phenyl-1,3,4-oxadiazol-2-ylamino)(4-trifluoromethylphenyl)methyl ligands were quantitatively obtained through the reaction of (E)-1-(4-trifluoromethylphenyl)-N-(5-phenyl-1,3,4-oxadiazol-2-yl)-methanimine with the ruthenium precursor [RuCl2(η6-p-cymene)]2 in a mixture of the corresponding alcohol and CH2Cl2 at 50 °C. The obtained complexes were fully characterized by elemental analysis, infrared, NMR and mass spectrometry. Solid-state structures confirmed the coordination of the 1,3,4-oxadiazole moiety to the ruthenium center via their electronically enriched nitrogen atom at position 3 in the aromatic ring. These complexes were evaluated as precatalysts in the Lemieux-Johnson type oxidative cleavage of olefins and alkynes in water at room temperature with NaIO4 as oxidizing agent. Good to full conversions of olefins into the corresponding aldehydes were measured, but low catalytic activity was observed in the case of alkynes. In order to get more insight into the mechanism, three analogue arene-ruthenium complexes were synthesized and tested in the oxidative cleavage of styrene. The latter tests clearly demonstrated the importance of the hemilabile alkyloxy groups, which may form more stable (N,O)-chelate intermediates and increase the efficiency of the cis-dioxo-ruthenium(VI) catalyst.
- Hkiri, Shaima,Touil, Soufiane,Samarat, Ali,Sémeril, David
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- Catalyst-Controlled Selectivity in Oxidation of Olefins: Highly Facile Success to Functionalized Aldehydes and Ketones
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The attractive challenge in green chemistry is exploring novel heterogeneous catalyst system for catalyst-controlled product selectivity for oxidation of olefins. Hence, we proposed efficient and green catalytic methods for the selective synthesis of alde
- Shen, Chao,Sun, Nabo,Wu, Huizhen,Xu, Hao,Yu, Wenbo,Zheng, Kai
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- Efficient and selective oxidation of hydrocarbons with tert-butyl hydroperoxide catalyzed by oxidovanadium(IV) unsymmetrical Schiff base complex supported on γ-Fe2O3 magnetic nanoparticles
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The catalytic activity of an oxidovanadium(IV) unsymmetrical Schiff base complex supported on γ-Fe2O3 magnetic nanoparticles, γ-Fe2O3@[VO(salenac-OH)] in which salenac-OH = [9-(2′,4′-dihydroxyphenyl)-5,8-diaza-4
- Ardakani, Mehdi Hatefi,Sabet, Mohammad,Samani, Mahnaz
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- Oxygen Atom Transfer Mechanism for Vanadium-Oxo Porphyrin Complexes Mediated Aerobic Olefin Epoxidation
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The development of catalytic aerobic epoxidation by numerous metal complexes in the presence of aldehyde as a sacrificial reductant (Mukaiyama epoxidation) has been reported, however, comprehensive examination of oxygen atom transfer mechanism involving free radical and highly reactive intermediates has yet to be presented. Herein, meso-tetrakis(pentafluorophenyl) porphyrinatooxidovanadium(IV) (VOTPFPP) was prepared and proved to be efficient toward aerobic olefin epoxidation in the presence of isobutyraldehyde. In situ electron paramagnetic resonance spectroscopy (in situ EPR) showed the generation, transfer pathways and ascription of free radicals in the epoxidation. According to the spectral and computational studies, the side-on vanadium-peroxo complexes are considered as the active intermediate species in the reaction process. In the cyclohexene epoxidation catalyzed by VOTPFPP, the kinetic isotope effect value of 1.0 was obtained, indicating that epoxidation occurred via oxygen atom transfer mechanism. The mechanism was further elucidated using isotopically labeled dioxygen experiments and density functional theory (DFT) calculations.
- Han, Qi,Huang, Jia-Ying,Ji, Hong-Bing,Liu, Xiao-Hui,Tao, Lei-Ming,Xue, Can,Yu, Hai-Yang,Zhou, Xian-Tai,Zou, Wen
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supporting information
p. 115 - 122
(2021/12/04)
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- Selective catalytic synthesis of bio-based high value chemical of benzoic acid from xylan with Co2MnO4@MCM-41 catalyst
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The efficient synthesis of bio-based chemicals using renewable carbon resources is of great significance to promote sustainable chemistry and develop green economy. This work aims to demonstrate that benzoic acid, an important high added value chemical in petrochemical industry, can be selectively synthesized using xylan (a typical model compound of hemicellulose). This novel controllable transformation process was achieved by selective catalytic pyrolysis of xylan and subsequent catalytic oxidation. The highest benzoic acid selectivity of 88.3 % with 90.5 % conversion was obtained using the 10wt%Co2MnO4@MCM-41 catalyst under the optimized reaction conditions (80 °C, 4 h). Based on the study of the model compounds and catalyst's characterizations, the reaction pathways for the catalytic transformation of xylan to bio-based benzoic acid were proposed.
- Fan, Minghui,He, Yuting,Li, Quanxin,Luo, Yuehui,Yang, Mingyu,Zhang, Yanhua,Zhu, Lijuan
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- Catalytic oxygen atom transfer promoted by tethered Mo(VI) dioxido complexes onto silica-coated magnetic nanoparticles
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The preparation of three novel active and stable magnetic nanocatalysts for the selective liquid-phase oxidation of several olefins, has been reported. The heterogeneous systems are based on the coordination of cis-MoO2 moiety onto three different SCMNP@Si-(L1-L3) magnetically active supports, functionalized with silylated acylpyrazolonate ligands L1, L2 and L3. Nanocatalysts thoroughly characterized by ATR-IR spectroscopy, TGA and ICP-MS analyses, showed excellent catalytic performances in the oxidation of conjugated or unconjugated olefins either in organic or in aqueous solvents. The good magnetic properties of these catalytic systems allow their easy recyclability, from the reaction mixture, and reuse over five runs without significant decrease in the activity, either in organic or water solvent, demonstrating their versatility and robustness.
- Colaiezzi, Roberta,Crucianelli, Marcello,Di Giuseppe, Andrea,Ferella, Francesco,Lazzarini, Andrea,Paolucci, Valentina
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- Nickel-Catalyzed Selective Synthesis of α-Alkylated Ketones via Dehydrogenative Cross-Coupling of Primary and Secondary Alcohols
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Herein, we describe an isolable, air-stable, homogeneous, nickel catalyst that performs dehydrogenative cross-coupling reaction between secondary and primary alcohols to result α-alkylated ketone products selectively. The sequence of steps involve in this one-pot reaction is dehydrogenation of both alcohols, condensation between the ketone and the aldehyde, and hydrogenation of the in situ-generated α,β-unsaturated ketone. Preliminary mechanistic investigation hints a radical mechanism following borrowing hydrogen reaction. (Figure presented.).
- Bains, Amreen K,Biswas, Ayanangshu,Adhikari, Debashis
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supporting information
p. 47 - 52
(2021/10/14)
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- A DFT and experimental study of the spectroscopic and hydrolytic degradation behaviour of some benzylideneanilines
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The spectroscopic and hydrolytic degradation behaviour of some N-benzylideneanilines are investigated experimentally and theoretically via high quality density function theoretical (DFT) modelling techniques. Their absorption and vibrational spectra, accurately predicted by DFT calculations, are highly dependent on the nature of the substituents on the aromatic rings, hence, though some of their spectroscopic features are similar, energetic differences exist due to differences in their electronic structures. Whereas the o-hydroxy aniline derived adducts undergo hydrolysis via two pathways, the most energetically economical of which is initiated by a fast enthalpy driven hydration, over a conservative free energy (ΔG?) barrier of 53 kJ mol?1, prior to the rate limiting entropy controlled lysis step which occurs via a conservative barrier of ca.132 kJ mol?1, all other compounds hydrolyse via a slower two-step pathway, limited by the hydration step. Barriers heights for both pathways are controlled primarily by the structure and hence, stability of the transition states, all of which are cyclic for both pathways.
- Nelson, Peter N.,Robertson, Tahjna I.
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- Electrochemical Aerobic Oxidative Cleavage of (sp3)C-C(sp3)/H Bonds in Alkylarenes
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An electrochemistry-promoted oxidative cleavage of (sp3)C-C(sp3)/H bonds in alkylarenes was developed. Various aryl alkanes can be smoothly converted into ketones/aldehydes under aerobic conditions using a user-friendly undivided cell setup. The features of air as oxidant, scalability, and mild conditions make them attractive in synthetic organic chemistry.
- Liu, Shuai,Liu, Zhong-Quan,Shen, Tong,Shen, Xu,Wang, Nengyong,Wu, Jintao,Yang, Le,Zhao, Jianyou
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p. 3286 - 3295
(2022/03/14)
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- The pH-Dependence of the Hydration of 5-Formylcytosine: an Experimental and Theoretical Study
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5-Formylcytosine is an important nucleobase in epigenetic regulation, whose hydrate form has been implicated in the formation of 5-carboxycytosine as well as oligonucleotide binding events. The hydrate content of 5-formylcytosine and its uracil derivative has now been quantified using a combination of NMR and mass spectroscopic measurements as well as theoretical studies. Small amounts of hydrate can be identified for the protonated form of 5-formylcytosine and for neutral 5-formyluracil. For neutral 5-formylcytosine, however, direct detection of the hydrate was not possible due to its very low abundance. This is in full agreement with theoretical estimates.
- Zott, Fabian L.,Korotenko, Vasily,Zipse, Hendrik
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- Wavelength-Specific Product Desorption as a Key to Raising Nitrile Yield of Primary Alcohol Ammoxidation over Illuminated Pd Nanoparticles
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Research on visible-light photocatalysts of metal nanoparticles (NPs) has focused on increasing the reactant conversion by light-excited charges (electrons and positively charged holes). However, light irradiation can accelerate catalysis by other mechanisms. Here, we report that 650 nm wavelength irradiation of 0.75 W·cm-2 significantly increases nitrile yield of ammoxidation of primary aromatic alcohols with an ammonium salt over supported Pd NPs at 80 °C in air. We found that the desorption of the nitrile product from the catalyst is the rate-determining step; the irradiation promotes not only alcohol oxidation and subsequent aldehyde cyanation over the Pd NPs but also the nitrile desorption selectively via resonance energy transfer to achieve a high nitrile yield. This new mechanism provides a knob for the exquisite control of catalytic reaction pathways for ecofriendly synthesis.
- Han, Pengfei,Tang, Cheng,Sarina, Sarina,Waclawik, Eric R.,Du, Aijun,Bottle, Steven E.,Fang, Yanfen,Huang, Yingping,Li, Kun,Zhu, Huai-Yong
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p. 2280 - 2289
(2022/02/14)
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- One-step solvent-free aerobic oxidation of aliphatic alcohols to esters using a tandem Sc-Ru?MOF catalyst
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Esters are an important class of chemicals in industry. Traditionally, ester production is a multi-step process involving the use of corrosive acids or acid derivatives (e.g. acid chloride, anhydride, etc.). Therefore, the development of a green synthetic protocol is highly desirable. This work reports the development of a metal-organic framework (MOF) supported tandem catalyst that can achieve direct alcohol to ester conversion (DAEC) using oxygen as the sole oxidizing agent under strictly solvent-free conditions. By incorporating Ru nanoparticles (NPs) along with a homogeneous Lewis acid catalyst, scandium triflate, into the nanocavities of a Zr MOF, MOF-808, the compound catalyst, Sc-Ru?MOF-808, can achieve aliphatic alcohol conversion up to 92% with ester selectivity up to 91%. A mechanistic study reveals a unique “via acetal” pathway in which the alcohol is first oxidized on Ru NPs and rapidly converted to an acetal on Sc(iii) sites. Then, the acetal slowly decomposes to release an aldehyde in a controlled manner for subsequent oxidation and esterification to the ester product. To the best of our knowledge, this is the first example of DAEC of aliphatic alcohols under solvent-free conditions with high conversion and ester selectivity.
- Feng, Tingkai,Li, Conger,Li, Tao,Zhang, Songwei
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supporting information
p. 1474 - 1480
(2022/03/08)
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- Enzyme engineering improves catalytic efficiency and enantioselectivity of hydroxynitrile lyase for promiscuous retro-nitroaldolase activity
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Protein engineering to improve promiscuous catalytic activity is important for biocatalytic application of enzymes in green synthesis. We uncovered the significance of binding site residues in Arabidopsis thaliana hydroxynitrile lyase (AtHNL) for promiscuous retro-nitroaldolase activity. Engineering of AtHNL has improved enantioselective retro-nitroaldolase activity, a synthetically important biotransformation, for the production of enantiopure β-nitroalcohols having absolute configuration opposite to that of the stereopreference of the HNL. The variant F179A has shown ～ 12 fold increased selectivity towards the retro-nitroaldol reaction over cyanogenesis, the natural activity of the parent enzyme. Screening of the two saturation libraries of Phe179 and Tyr14 revealed several variants with higher kcat, while F179N showed ～ 2.4-fold kcat/Km than the native enzyme towards retro-nitroaldol reaction. Variants F179N, F179M, F179W, F179V, F179I, Y14L, and Y14M have shown > 99% ee in the preparation of (S)-2-nitro-1-phenylethanol (NPE) from the racemic substrate, while F179N has shown the E value of 138 vs. 81 by the wild type. Our molecular docking and dynamics simulations (MDS) studies results provided insights into the molecular basis of higher enantioselectivity by the F179N toward the retro-nitroaldolase activity than the other mutants. Binding energy calculations also showed the higher negative binding free energy in the case of F179N-(R)-NPE compared to other complexes that support our experimental low Km by the F179N for NPE. A plausible retro-nitroaldol reaction mechanism was proposed based on the MDS study of enzyme-substrate interaction.
- Akif, Mohd.,Gilani, Rubina,Kumar Padhi, Santosh,Lata, Surabhi,Rai, Nivedita,Sreenivasa Rao, D. H.,Vishnu Priya, Badipatla
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- Selective Encapsulation and Unusual Stabilization of cis-Isomers by a Spherical Polyaromatic Cavity
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To explore new cavity functions, we herein employed cis-trans stereoisomers with a N=N, C=C, or C=N unit as guest indicators for a polyaromatic capsule. Thanks to the rigid, spherical cavity with a diameter of ～1 nm, azobenzene and stilbene derivatives ar
- Yuasa, Mana,Sumida, Ryuki,Tanaka, Yuya,Yoshizawa, Michito
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supporting information
(2022/02/02)
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- Synthesis of aluminum doped MIL-100(Fe) compounds for the one-pot photocatalytic conversion of cinnamaldehyde and benzyl alcohol to the corresponding alcohol and aldehyde under anaerobic conditions
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Fully utilizing the photogenerated electrons and holes in a photocatalytic process is a promising way to enhance catalytic efficiency and achieve atomic economy. Here, conjugated photocatalytic redox reactions, i.e. hydrogenation of cinnamaldehyde (CAL) t
- Guo, Binbin,Kang, Yueyue,Shi, Yingzhang,Wang, Zhiwen,Wu, Ling
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p. 184 - 192
(2022/02/03)
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- Catalytic epoxidation of β-ionone with molecular oxygen using selenium-doped silica materials
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A novel Se-doped silica material was fabricated, and this easily prepared material could be used as an efficient recyclable catalyst for β-ionone oxidation. Interestingly, by doping with fluorine in the catalyst, the reaction selectivity was significantly enhanced to produce the important pharmaceutical intermediate β-ionone epoxide selectively. Characterization of the materials indicated that by doping with F, the electropositivity of the catalytic Se species was obviously enhanced due to the strong electron-withdrawing features of F, and this was a key factor for controlling the reaction selectivity in the β-ionone epoxidation reaction. The electropositivity of a silica support might also increase and the reinforced electropositivity of Si sites might be beneficial for the adsorption of a β-ionone substrate and for the contact of the electron-enriched endocyclic C-C with the catalyst.
- Cao, Kuanhong,Jing, Xiaobi,Li, Peizi,Liu, Yonghong,Yu, Lei
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p. 17241 - 17246
(2021/10/04)
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- Nitrosoarene-Catalyzed HFIP-Assisted Transformation of Arylmethyl Halides to Aromatic Carbonyls under Aerobic Conditions
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A rare metal-free nucleophilic nitrosoarene catalysis accompanied by highly hydrogen-bond-donor (HBD) solvent, 1,1,1,3,3,3-hexafluoro-2-propanol (HFIP), organocatalytically converts arylmethyl halides to aromatic carbonyls. This protocol offers an effective means to access a diverse array of aromatic carbonyls with good chemoselectivity under mild reaction conditions. The activation of arylmethyl halides by HFIP to generate stable carbocation and autoxidation of in situ generated hydroxylamine to nitrosoarene in the presence of atmospheric O2 are the keys to success.
- Pradhan, Suman,Sharma, Vishali,Chatterjee, Indranil
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supporting information
p. 6148 - 6152
(2021/08/03)
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- Tris(pentafluorophenyl)borane-Catalyzed Formal Cyanoalkylation of Indoles with Cyanohydrins
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Despite the significant achievements related to the C3 functionalization of indoles, cyanoalkylation reactions continue to remain rather limited. We herein report on the formal C3 cyanoalkylation of indoles with cyanohydrins in the presence of a tris(pentafluorophenyl)borane (B(C6F5)3) catalyst. It is noteworthy that cyanohydrins are used as a cyanoalkylating reagent in the present reaction, even though they are usually used as only a HCN source. Mechanistic investigations revealed the unique reactivity of the B(C6F5)3 catalyst in promoting the decomposition of a cyanohydrin by a Lewis acidic activation through the coordination of the cyano group to the boron center. In addition, a catalytic three-component reaction using indoles, aldehydes as a carbon unit, and acetone cyanohydrin that avoids the discrete preparation of each aldehyde-derived cyanohydrin is also reported. The developed methods provide straightforward, highly efficient, and atom-economic access to various types of synthetically useful indole-3-acetonitrile derivatives containing α-tertiary or quaternary carbon centers.
- Kiyokawa, Kensuke,Minakata, Satoshi,Urashima, Naruyo
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p. 8389 - 8401
(2021/06/28)
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- Highly efficient and selectivity-controllable aerobic oxidative cleavage of C-C bond over heterogeneous Fe-based catalysts
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A base-free selectivity-controllable aerobic oxidative cleavage of C-C bond with heterogeneous Fe-based catalysts (FexOy-N@C3N4) is developed. In the presence of oxygen, 1,2-diols are selectively transformed to the corresponding aldehyde, while the methyl esters are orientedly produced from 1,2-diones in methanol medium.
- Guo, Pengfei,Liao, Shengyun,Wang, Shun,Shi, Jing,Tong, Xinli
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p. 399 - 403
(2021/02/27)
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- Dibismuthanes in catalysis: From synthesis and characterization to redox behavior towards oxidative cleavage of 1,2-diols
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A family of aryl dinuclear bismuthane complexes has been successfully synthesized and characterized. The two bismuth centers are bonded to various xanthene-type backbones, which differ in ring-size and flexibility, resulting in complexes with different intramolecular Bi?Bi distances. Moreover, their pentavalent Bi(v) analogues have also been prepared and structurally characterized. Finally, the synergy between bismuth centers in catalysis has been studied by applying dinuclear bismuthanes5-8to the catalytic oxidative cleavage of 1,2-diols. Unfortunately, no synergistic effects were observed and the catalytic activities of dinuclear bismuthanes and triphenylbismuth are comparable.
- Magre, Marc,Kuziola, Jennifer,N?thling, Nils,Cornella, Josep
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supporting information
p. 4922 - 4929
(2021/06/16)
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- Poly(ethylene glycol) dimethyl ether mediated oxidative scission of aromatic olefins to carbonyl compounds by molecular oxygen
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A simple, and practical oxidative scission of aromatic olefins to carbonyl compounds using O2as the sole oxidant with poly(ethylene glycol) dimethyl ether as a benign solvent has been developed. A wide range of monosubstituted,gem-disubstituted, 1,2-disubstituted, trisubstituted and tetrasubstituted aromatic olefins was successfully converted into the corresponding aldehydes and ketones in excellent yields even with gram-scale reaction. Some control experiments were also conducted to support a possible reaction pathway.
- Yu, Tao,Guo, Mingqing,Wen, Simiaomiao,Zhao, Rongrong,Wang, Jinlong,Sun, Yanli,Liu, Qixing,Zhou, Haifeng
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p. 13848 - 13852
(2021/04/22)
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- Hydroxyl radical-mediated oxidative cleavage of CC bonds and further esterification reaction by heterogeneous semiconductor photocatalysis
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A hydroxyl radical-mediated aerobic cleavage of alkenes and further sequence esterification reaction for the preparation of carbonyl compounds have been developed by using tubular carbon nitride (TCN) as a general heterogeneous photocatalyst under an oxygen atmosphere with visible light irradiation. This protocol has an excellent substrate scope and gives the desired aldehydes, ketones and esters in moderate to high yields. Importantly, this metal-free procedure employed photogenerated hydroxyl radicals in situ as green oxidation active species, avoiding the present additional initiators. The reaction could be carried out under solar light irradiation and was applicable to large-scale reactions. Furthermore, the recyclable TCN catalyst could be used several times without a significant loss of activities.
- Hong, Mei,Jia, Rui,Miao, Hongyan,Ni, Bangqing,Niu, Tengfei,Wang, Hui
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p. 6591 - 6597
(2021/09/10)
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- METHOD FOR PREPARING BENZALDEHYDE
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Are a method for producing benzaldehyde and a carbon electrode for producing benzaldehyde. The process produces benzaldehyde by oxidizing toluene through direct electron exchange between the carbon electrode and toluene. The process is performed at room t
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Paragraph 0058-0074
(2021/04/06)
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- Mixed Micelles of Surface Active Ionic Liquid (SAIL)–Octylphenol Ethoxylate: A Novel Reaction Medium for Selective Oxidation of Toluene to Benzaldehyde
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Ionic liquids have been found to be suitable alternatives to volatile organic solvents in chemical transformation. Through a proper choice of cations and anions, the properties of an ionic liquid can be tuned so that it resembles an amphiphile. Such specially designed molecules are known as surface-active ionic liquids (SAIL). Like conventional surfactants, SAIL also form aggregates in an aqueous medium. Studies show that the mixing of SAIL with conventional surfactants leads to synergistic micellization. However, very few reports are available on the application of such systems as reaction media. Present study focuses on the application of mixed micelles of 1-tetradecyl-3-methylimidazol-1-ium bromide, ([C14mim]Br) with nonionic surfactant, Octylphenol ethoxylate with 10 moles of ethylene oxide (OPE-10). Enhanced solubilization and selective catalytic oxidation of toluene using hydrogen peroxide as an oxidant and tungstic acid as a catalyst have been studied in detail using this system.
- Deore, Tushar S.,Sadgar, Amid L.,Jayaram, Radha V.
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p. 185 - 190
(2020/07/30)
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- High dimensionally structured W-V oxides as highly effective catalysts for selective oxidation of toluene
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High dimensionally structured W-V-O catalysts (HDS-WVO) were synthesized by hydrothermal method and catalyst structures were investigated by HAADF-STEM analysis. HDS-WVO were rod-shaped crystals and the cross-sections were constituted by W6O21 pentagonal units and MO6 octahedra (M = V, W), forming heptagonal and hexagonal channels. HDS-WVO catalysts showed excellent catalytic performance for selective oxidation of toluene to benzoic acid, and the activity and the selectivity to benzoic acid were superior to those of state-of-the-art catalysts. After the ion exchange using Cs+, the catalytic activity over HDS-WVO was significantly decreased. Since HAADF-STEM analysis and N2 adsorption revealed that Cs+ was located mainly at the heptagonal channel of HDS-WVO, it can be concluded that toluene oxidation takes place at the heptagonal channel site of HDS-WVO.
- Murayama, Toru,Ishikawa, Satoshi,Hiyoshi, Norihito,Goto, Yoshinori,Zhang, Zhenxin,Toyao, Takashi,Shimizu, Ken-ichi,Lee, Shutoku,Ueda, Wataru
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- V2O5@TiO2 Catalyzed Green and Selective Oxidation of Alcohols, Alkylbenzenes and Styrenes to Carbonyls
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The versatile application of different functional groups such as alcohols (1° and 2°), alkyl arenes, and (aryl)olefins to construct carbon-oxygen bond via oxidation is an area of intense research. Here, we report a reusable heterogeneous V2O5@TiO2 catalyzed selective oxidation of various functionalities utilizing different mild and eco-compatible oxidants under greener reaction conditions. The method was successfully applied for the alcohol oxidation, oxidative scission of styrenes, and benzylic C?H oxidation to their corresponding aldehydes and ketones. The utilization of mild and eco-friendly oxidizing reagents such as K2S2O8, H2O2 (30 % aq.), TBHP (70 % aq.), broad substrate scope, gram-scale synthesis, and catalyst recyclability are notable features of the developed protocol.
- Upadhyay, Rahul,Kumar, Shashi,Maurya, Sushil K.
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p. 3594 - 3600
(2021/07/02)
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- Study of ethylbenzene oxidation over polymer-silica hybrid supported Co (II) and Cu (II) complexes
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Polymer-silica hybrid support (SA-2-AMPS-SiO2) was synthesized and Co (II), Cu (II) metals were loaded over hybrid support by incipient impregnation technique. Oxidation of ethylbenzene was carried out for testing catalytic activity of catalyst
- Chaudhary, Vasu,Sharma, Sweta
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p. 601 - 613
(2020/03/10)
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- Preparation and characterization of a copper oxide nanoparticle-supported red-mud catalyst for liquid phase oxidation of ethyl benzene to acetophenone
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In this study, liquid phase oxidation of ethyl benzene to acetophenone was widely investigated using a new recyclable supported catalyst of CuO nanoparticles impregnated over activated red-mud (CuO_AARM). The catalyst was prepared using a hydrothermal rea
- Bal, Rajaram,Dey, Ratan Kumar,Mishra, Subhashree,Sangma, Simon Watre
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supporting information
p. 13070 - 13079
(2021/08/03)
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- Copper-catalyzed efficient access to 2,4,6-triphenyl pyridinesviaoxidative decarboxylative coupling of aryl acetic acids with oxime acetates
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An efficient and concise approach for the synthesis of 2,4,6-triphenyl pyridines has been developed through copper-catalysed oxidative decarboxylative coupling of C(sp3) aryl acetic acids with oxime acetates in DMF at 150 °C under an oxygen atm
- Bharat Kumar, Karasala,Chinnari, Lekkala,Shyamala, Pulipaka,Siddaiah, Vidavalur,Varaprasad, Bodala
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p. 15205 - 15209
(2021/09/06)
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- Improved, gram-scale synthesis of sildenafil in water using arylacetic acid as the acyl source in the pyrazolo[4,3-d]pyrimidin-7-one ring formation
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An improved, gram-scale synthesis of the blockbuster drug sildenafil, used for the treatment of male erectile dysfunction, has been developed. Unlike the previous literature, the current method demonstrates the use of arylacetic acid as an acyl source, a cheap oxidant K2S2O8, and water as the reaction medium in the key step of pyrrazolo[4,3-d]pyrimidin-7-one ring formation. As well as being a green and benign approach, the current method reduces the cost by half compared to our previous strategy. In addition, the general relevance of the method has been demonstrated in the synthesis of a variety of quinazolinone and benzothiazole derivatives with excellent functional group tolerance.
- Laha, Joydev K.,Gulati, Upma,Saima,Gupta, Anjali,Indurthi, Harish Kumar
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supporting information
p. 2643 - 2648
(2021/02/16)
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- Rapid, chemoselective and mild oxidation protocol for alcohols and ethers with recyclable N-chloro-N-(phenylsulfonyl)benzenesulfonamide
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Chlorine is the 20th most abundant element on the earth compared to bromine, iodine, and fluorine, a sulfonimide reagent, N-chloro-N-(phenylsulfonyl)benzenesulfonamide (NCBSI) was identified as a mild and selective oxidant. Without activation, the reagent was proved to oxidize primary and secondary alcohols as well as their symmetrical and mixed ethers to corresponding aldehydes and ketones. With recoverable PS-TEMPO catalyst, selective oxidation over chlorination of primary and secondary alcohols and their ethers with electron-donating substituents was achieved. The reagent precursor of NCBSI was recovered quantitatively and can be reused for synthesizing NCBSI.
- Badani, Purav,Chaturbhuj, Ganesh,Ganwir, Prerna,Misal, Balu,Palav, Amey
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supporting information
(2021/06/03)
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- Merging N-Hydroxyphthalimide into Metal-Organic Frameworks for Highly Efficient and Environmentally Benign Aerobic Oxidation
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Two highly efficient metal-organic framework catalysts TJU-68-NHPI and TJU-68-NDHPI have been successfully synthesized through solvothermal reactions of which the frameworks are merged with N-hydroxyphthalimide (NHPI) units, resulting in the decoration of pore surfaces with highly active nitroxyl catalytic sites. When t-butyl nitrite (TBN) is used as co-catalyst, the as-synthesized MOFs are demonstrated to be highly efficient and recyclable catalysts for a novel three-phase heterogeneous oxidation of activated C?H bond of primary and secondary alcohols, and benzyl compounds under mild conditions. Based on the high efficiency and selectivity, an environmentally benign system with good sustainability, mild conditions, simple work-up procedure has been established for practical oxidation of a wide range of substrates.
- Wang, Man,Liang, Gan,Wang, Yunhao,Fan, Tao,Yuan, Baoling,Liu, Mingxian,Yin, Ying,Li, Liangchun
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supporting information
p. 9674 - 9685
(2021/06/09)
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- Trans(Cl)-2,2′-bipyridinedicarbonyldichlororuthenium(II) complex catalyzed oxidation of olefins, aryl hydrocarbons and alcohols in homogeneous phase
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Catalytic oxidation of organic substrates has wide applications in chemical industries due to which huge extensive research work is continuously going on throughout the world. Present study reports efficacious use of Trans (Cl)-2,2′-bipyridinedicarbonyldichlororuthenium(II) complex catalyzed oxidation of internal and terminal olefins, aryl hydrocarbons and alcohols. CH2Cl2–C2H5OH (6:4) was suitable solvent system for these oxidation reactions. The normal pressure oxidation reaction has been carried out at 1 ?atm. Pressure of oxygen and at 300C. The high pressure oxidation reaction was done at 4.48 ?× ?103 KNm3 pressure of oxygen and at 600C. No diminished catalytic activity was observed while checking the recyclability of catalyst up to 6–8 catalytic runs. Catalytic activity was also investigated using tert-butyl hydroperoxide as oxidant inspite of di-oxygen. Effect of different parameters on the rate of oxidation was also studied i.e. extra ligand, temperature, solvents, acids and bases. Kinetic studies have been done and on the basis of kinetics, the mechanism is proposed.
- Sharma, Varsha,Pant, Bhawana,Prakash, Deep,Sagar, Priyanka
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- Method for generating benzaldehyde by catalyzing alpha-monosubstituted styrene to be oxidized by N-hydroxyphthalimide
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The invention discloses a method for generating benzaldehyde by catalyzing alpha-mono-substituted styrene to be oxidized through N-hydroxyphthalimide. According to the method, N-hydroxyphthalimide isused as a catalyst, oxygen is used as an oxidizing agent, and an alpha mono-substituted styrene compound is oxidized in an organic solvent to obtain the benzaldehyde derivative. The method has the advantages of simple reaction operation, low cost, mild conditions, high yield, no heavy metal pollution and the like.
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Paragraph 0039-0041
(2021/01/24)
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- Selective oxidation of alkenes to carbonyls under mild conditions
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Herein, a practical and sustainable method for the synthesis of aldehydes, ketones, and carboxylic acids from an inexpensive olefinic feedstock is described. This transformation features very sustainable and mild conditions and utilizes commercially available and inexpensive tetrahydrofuran as the additive, molecular oxygen as the sole oxidant and water as the solvent. A wide range of substituted alkenes were found to be compatible, providing the corresponding carbonyl compounds in moderate-to-good yields. The control experiments demonstrated that a radical mechanism is responsible for the oxidation reaction.
- Huo, Jie,Xiong, Daokai,Xu, Jun,Yue, Xiaoguang,Zhang, Pengfei,Zhang, Yilan
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supporting information
p. 5549 - 5555
(2021/08/16)
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- Photo-induced oxidative cleavage of C-C double bonds for the synthesis of biaryl methanoneviaCeCl3catalysis
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A Ce-catalyzed strategy is developed to produce biaryl methanonesviaphotooxidative cleavage of C-C double bonds at room temperature. This reaction is performed under air and demonstrates high activity as well as functional group tolerance. A synergistic Ce/ROH catalytic mechanism is also proposed based on the experimental observations. This protocol should be the first successful Ce-catalyzed photooxidation reaction of olefins with air as the oxidant, which would provide inspiration for the development of novel Ce-catalyzed photochemical synthesis processes.
- Xie, Pan,Xue, Cheng,Du, Dongdong,Shi, SanShan
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supporting information
p. 6781 - 6785
(2021/08/20)
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- Decatungstate-mediated solar photooxidative cleavage of CC bonds using air as an oxidant in water
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With the increasing attention for green chemistry and sustainable development, there has been much interest in searching for greener methods and sources in organic synthesis. However, toxic additives or solvents are inevitably involved in most organic transformations. Herein, we first report the combination of direct utilization of solar energy, air as the oxidant and water as the solvent for the selective cleavage of CC double bonds in aryl olefins. Various α-methyl styrenes, diaryl alkenes as well as terminal styrenes are well tolerated in this green and sustainable strategy and furnished the desired carbonyl products in satisfactory yields. Like heterogeneous catalysis, this homogeneous catalytic system could also be reused and it retains good activity even after repeating three times. Mechanism investigations indicated that both O2- and 1O2 were involved in the reaction. Based on these results, two possible mechanisms, including the electron transfer pathway and the energy transfer pathway, were proposed.
- Du, Dongdong,Luo, Junfei,Shi, Sanshan,Xie, Pan,Xue, Cheng
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p. 5936 - 5943
(2021/08/23)
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- Aerobic oxidative C?C bond cleavage of aromatic alkenes by a high valency iron-containing perovskite catalyst
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High valency iron-containing perovskite catalyst BaFeO3-dcould efficiently promote the additive-free oxidative C?C bond cleavage of various aromatic alkenes to the corresponding aldehydes or ketones using O2as the sole oxidant. This system was applicable to the gram-scale oxidation of 1,1-diphenylethylene, in which 2.71 g (75% yield) of the analytically pure ketone could be isolated.
- Shibata, Satomi,Kamata, Keigo,Hara, Michikazu
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p. 2369 - 2373
(2021/04/22)
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- Two new polyoxoniobosilicate-based compounds: Syntheses, structures, characterizations and their catalytic properties for epoxidation and water oxidation
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Two new polyoxoniobosilicates, Na12[Cu(en)2(H2O)2]5[H3(SiOH)2Si2Nb16O54]2·52H2O (1) and K4[Cu(en)2(H
- Zhang, Ting-Ting,Zhao, Zi-Qiu,Tian, Ge,Cui, Xiao-Bing
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- Mono-copper substituted phosphotungstate supported on to neutral alumina: Synthesis, characterization and detailed studies for oxidation of styrene
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Mono-copper substituted phosphotungstate (PW11Cu) was supported on a neutral support (alumina) by wet impregnation method, which is the first instance of the use of alumina for supporting Transition metal substituted Polyoxometalates (TMSPOMs),
- Sadasivan, Rajesh,Patel, Anjali
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- Synthesis, structure, magnetic and catalytic competency of a tetradentate (nnoo) schiff base mediated dimeric copper(ii) complex
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One dinuclear copper(II) complex {μ-[2,2 -{ethane-1,2-diylbis[(azanylylidene)methanylylidene]}bis(phenolato)]}-{μ-[2,2 -{ethane-1,2- diylbis[(azanylylidene)methanylylidene]}bis(phenolato)]}dicopper(II), [Cu2(salen)2] (1) [salen2- = [2,2 -{ethane-1,2-diylbis- [(azanylylidene)methanylylidene]}bis(phenolato)] has been isolated and characterized by X-ray diffraction analysis and spectroscopic studies. X-ray single crystal structure examination revealed that each Cu(II) center in the asymmetric unit of 1 adopts a distorted square planar geometry with a CuN2O2 chromophore, where two asymmetric units are attached through congregation of Salen involving Cu-O bond to form dinuclear molecular unit [Cu2(salen)2]. In crystalline state, these dinuclear entities in 1 are extended through C-H π interactions and π π interactions displaying a 3D network structure. The variable-temperature magnetic susceptibility measurement asserted a dominant antiferromagnetic interaction between the copper(II) centers through Cu-O-Cu linkage in 1 with J = -1.46 cm-1. The catalytic efficacy of complex 1 was studied in a series of solvents for the oxidation of styrene and cyclooctene using tert-butyl-hydroperoxide (TBHP) as an active oxidant under mild conditions. The catalytic reaction mixture has been analyzed by gas chromatography and it displayed that the yield of the epoxidation and its selectivity is optimum in acetonitrile medium.
- CHOWDHURY, HABIBAR,BERA, RAJESH,ADHIKARY, CHANDAN
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p. 1280 - 1286
(2021/06/09)
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- Substituent effects in dioxovanadium(V) schiff-base complexes: Tuning the outcomes of oxidation reactions
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Dioxovanadium(V) salicylaldehyde semicarbazone complexes with substituents on the ligand that span the range of electron donating (methoxy) to electron withdrawing (nitro) have been synthesized and characterized by NMR, IR, CV and EPR. The reactivity of these complexes toward the oxidation of styrene (as compared to the proteo complex and vanadyl acetylacetonate) has been studied in the presence of two different oxidants (hydrogen peroxide and tert-butyl hydrogen peroxide, TBHP). The complexes have been shown to exhibit different selectivity towards epoxidation versus oxidative cleavage based on the substitution of the ligand and the oxidant chosen. Epoxidation is favored with the methoxy substituted complex in the presence of hydrogen peroxide, while oxidative cleavage is the preferred reaction pathway for the nitro substituted complex with hydrogen peroxide. Conversions for these reaction are comparable to similar catalysts but with improved selectivity.
- McCaffrey, Vanessa P.,Conover, Olivia Q.,Bernard, Michael A.,Yarranton, Jonathan T.,Lessnau, Nicholas R.,Hempfling, Jordan P.
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- Efficient, Solvent Free and Selective Oxidation of Styrene to Benzaldehyde Over Niobium Modified Phosphomolybdic Acid Catalyst
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Niobium substituted phosphomolybdic acid with various Nb/P mole ratio of catalysts were successfully synthesised by hydrothermal method. These materials were characterized by X-ray diffraction, FT-IR spectroscopy, Raman spectroscopy, temperature programme
- Chary, Komandur V. R.,Viswanadham, Balaga
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- Preparation of zeolitic bismuth vanadomolybdate using a ball-shaped giant polyoxometalate for olefin epoxidation
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Zeolitic octahedral metal oxides are interesting materials that have received increasing attention. A bismuth vanadomolybdate-based zeolitic octahedral metal oxide was synthesized using a ball-shaped polyoxovanadomolybdate with different Bi sources. The material was used as a heterogeneous catalyst for olefin epoxidation. Different olefins were converted to their corresponding epoxides by the catalyst under mild conditions. This robust catalyst was reused several times without loss of activity.
- Hara, Michikazu,Li, Denan,Li, Yanshuo,Ueda, Wataru,Zhang, Zhenxin,Zhu, Qianqian
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p. 21624 - 21630
(2021/12/09)
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- Oxidative carbon-carbon bond cleavage of 1,2-diols to carboxylic acids/ketones by an inorganic-ligand supported iron catalyst
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The carbon-carbon bond cleavage of 1,2-diols is an important chemical transformation. Although traditional stoichiometric and catalytic oxidation methods have been widely used for this transformation, an efficient and valuable method should be further explored from the views of reusable catalysts, less waste, and convenient procedures. Herein an inorganic-ligand supported iron catalyst (NH4)3[FeMo6O18(OH)6]·7H2O was described as a heterogeneous molecular catalyst in acetic acid for this transformation in which hydrogen peroxide was used as the terminal oxidant. Under the optimized reaction conditions, carbon-carbon bond cleavage of 1,2-diols could be achieved in almost all cases and carboxylic acids or ketones could be afforded with a high conversion rate and high selectivity. Furthermore, the catalytic system was used efficiently to degrade renewable biomass oleic acid. Mechanistic insights based on the observation of the possible intermediates and control experiments are presented.
- Chen, Weiming,Xie, Xin,Zhang, Jian,Qu, Jian,Luo, Can,Lai, Yaozhu,Jiang, Feng,Yu, Han,Wei, Yongge
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p. 9140 - 9146
(2021/11/23)
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- Metal-free selective reduction of acid chlorides to aldehydes using 1-hydrosilatrane
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This work uses 1-hydrosilatrane – an accessible and easy-to-handle reducing reagent – to selectively reduce acid chlorides to aldehydes. This metal-free reduction proceeds rapidly at ambient temperature in the presence of N-methylpyrrolidine, efficiently producing aldehydes in up to 54% yield and with the balance largely remaining as starting material. No over-reduced alcohol product is observed.
- Adler, Marc J.,Azam, Fawwaz,Raveenthrarajan, David
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supporting information
(2021/10/29)
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- Oxidation/ MCR domino protocol for direct transformation of methyl benzene, alcohol, and nitro compounds to the corresponding tetrazole using a three-functional redox catalytic system bearing TEMPO/Co(III)-porphyrin/ Ni(II) complex
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A redox catalytic system for oxidation-reduction reactions and the domino preparation of tetrazole compounds from nitro and alcohol precursors was designed, prepared and characterized by UV–vis, GPC, TGA, XRD, EDX, XPS, VSM, FE-SEM, TEM, DLS, BET, NMR, and ICP analyses. The catalyst was prepared via several successive steps by demetalation of chlorophyll b, copolymerization with acrylated TEMPO monomers, complexation with Ni and Co metals (In two different steps), then immobilized on magnetic nanoparticles. The presence of three functional groups including TEMPO, coordinated cobalt, and coordinated nickel in the catalyst, allowed the oxidation of various types of alcohols, alkyl benzenes as well as the reduction of nitro compounds by a single catalyst. All reactions yielded up to 97 % selectivity for oxidation and reduction reactions. Next, the ability of the catalyst to successfully convert alcohol, methyl benzenes and nitro to their corresponding tetrazoles was studied.
- Mahmoudi, Boshra,Rostami, Amin,Kazemnejadi, Milad,Hamah-Ameen, Baram Ahmed
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- Ferric ion concentration-controlled aerobic photo-oxidation of benzylic C–H bond with high selectivity and conversion
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A Fe(III)-promoted highly selective photo-oxidation of benzylic C–H bond delivering relative carbonyl products is reported. By altering the concentration of ferric salt, methylarenes can be selectively oxidized under UV irradiation to furnish aromatic aldehydes or acids, respectively. By this protocol, the oxidation of ethylarenes provides the corresponding acetophenones. The reaction is inferred to involve divergent pathways in different concentrations of catalyst for the alternative selectivity between aldehydes and aicds. The reusable catalyst, high conversion and selectivity make this oxidation a green and economic protocol for the synthesis of aromatic carbonyl compounds.
- Bu, Hongzhong,Gu, Jiefan,Li, Yufeng,Ma, Hongfei,Wan, Yuting,Wu, Zheng-Guang,Zhang, Weijian,Zhou, Ying'ao,Zhu, Hongjun
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