- Benzylic Hydroperoxidation via Visible-Light-Induced Csp3-H Activation
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A highly efficient benzylic hydroperoxidation has been realized through a visible-light-induced Csp3-H activation. We believe that this reaction undergoes a direct HAT mechanism catalyzed by eosin Y. This approach features the use of a metal-free catalyst (eosin Y), an energy-economical light source (blue LED), and a sustainable oxidant (molecular oxygen). Primary, secondary, and tertiary hydroperoxides as well as silyl, benzyl, and acyl peroxides were successfully prepared with good yields and excellent functional group compatibility.
- Inoa, Joan,Patel, Mansi,Dominici, Grecia,Eldabagh, Reem,Patel, Anjali,Lee, John,Xing, Yalan
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p. 6181 - 6187
(2020/05/22)
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- Competition H(D) kinetic isotope effects in the autoxidation of hydrocarbons
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Hydrogen atom transfer is central to many important radical chain sequences. We report here a method for determination of both the primary and secondary isotope effects for symmetrical substrates by the use of NMR. Intramolecular competition reactions were carried out on substrates having an increasing number of deuterium atoms at symmetry-related sites. Products that arise from peroxyl radical abstraction at each position of the various substrates reflect the competition rates for H(D) abstraction. The primary KIE for autoxidation of tetralin was determined to be 15.9 ± 1.4, a value that exceeds the maximum predicted by differences in H(D) zero-point energies (~7) and strongly suggests that H atom abstraction by the peroxyl radical occurs with substantial quantum mechanical tunneling.
- Muchalski, Hubert,Levonyak, Alexander J.,Xu, Libin,Ingold, Keith U.,Porter, Ned A.
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- Fabrication of CuCr2O4 spinel nanoparticles: A potential catalyst for the selective oxidation of cycloalkanes via activation of Csp3-H bond
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We report here preparation of CuCr2O4 spinel nanoparticle catalyst, mediated by cationic surfactant CTAB in hydrothermal route. XRD revealed the formation of CuCr2O4 spinel phase and TEM showed the particle size of 30-60 nm. The catalyst was speculated to be highly active for selective oxidation of cyclohexane to cyclohexanone with H2O2. A cyclohexane conversion of 70% with 85% cyclohexanone selectivity was achieved over this catalyst at 50 °C temperature. Moreover, the catalyst did not show any significant activity loss even after 8 reuses and proved its efficacy in the oxidation of other cycloalkanes also.
- Acharyya, Shankha S.,Ghosh, Shilpi,Adak, Shubhadeep,Tripathi, Deependra,Bal, Rajaram
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supporting information
p. 145 - 150
(2015/01/09)
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- Selective aerobic oxidation of activated alkanes with MOFs and their use for epoxidation of olefins with oxygen in a tandem reaction
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MOFs with Cu2+ centers linked to four nitrogen atoms from azaheterocyclic compounds, i.e., pyrimidine [Cu(2-pymo)2] and imidazole [Cu(im)2], are active catalysts for aerobic oxidation of activated alkanes, such as tetralin, cumene and ethylbenzene. Differences in activity among the two MOFs appear to be related to differences in their ability to decompose the hydroperoxide and to coordinate to the resulting radical OH species. Copper ions in [Cu(im)2] can coordinate by expanding their coordination sphere from 4 to 5 in a reversible way, while in the case of [Cu(2-pymo)2] it results in a displacement of one of the pyrimidine ligands. The MOFs can be used in combination with a silylated Ti-MCM-41 to catalyze the epoxidation of olefins with oxygen by means of a tandem reaction in which the MOF produces cumene hydroperoxide, which is used by Ti-MCM-41 to epoxidize the olefin. The Royal Society of Chemistry 2013.
- Luz,Leon,Boronat,Llabres I Xamena,Corma
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p. 371 - 379
(2013/03/14)
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- Superhydrophobic materials as efficient catalysts for hydrocarbon selective oxidation
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A new type of superhydrophobic material, FP-Co-SiO2 was prepared with organic groups immobilized on the surface of the SiO2-based nanocomposite. This material showed much higher catalytic activity for selective oxidation of hydrocarbons than an equivalent hydrophilic catalyst.
- Chen, Chen,Xu, Jie,Zhang, Qiaohong,Ma, Yinf,Zhou, Lipeng,Wang, Min
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supporting information; scheme or table
p. 1336 - 1338
(2011/03/22)
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- Highly selective oxidation of tetralin to 1-tetralone over mesoporous CrMCM-41 molecular sieve catalyst using supercritical carbon dioxide
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Selective oxidation of tetralin by molecular oxygen over mesoporous CrMCM-41 molecular sieve catalyst using supercritical carbon dioxide (scCO 2) solvent has been investigated. CrMCM-41 catalyst gave high selectivity (96.2%) and good yield (63.4%) of 1-tetralone. The presence of scCO2 medium improves 1-tetralone selectivity and suppresses leaching of chromium from the CrMCM-41. The activity over recycled CrMCM-41 remains nearly the same under the present experimental conditions. The effect of the reaction parameters on CrMCM-41 was also studied in detail along with comparison of its catalytic activities with other mesoporous catalysts, viz. MnMCM-41, CoMCM-41, microporous CrAPO-5, CoMFI, and macroporous Cr/SiO2 catalyst, respectively. In addition this catalytic system was also applied for the oxidation of other benzylic compounds such as indane, fluorene, acenaphthene and diphenylmethane. The Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2009.
- Dapurkar, Sudhir E.,Kawanami, Hajime,Yokoyama, Toshirou,Ikushima, Yutaka
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body text
p. 538 - 544
(2009/05/30)
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- Metal organic frameworks (MOFs) as catalysts: A combination of Cu2+ and Co2+ MOFs as an efficient catalyst for tetralin oxidation
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Two metal-organic frameworks, [Cu(2-pymo)2] and [Co(PhIM)2] (2-pymo = 2-hydroxypyrimidinolate; PhIM = phenylimidazolate), containing respectively Cu2+ and Co2+ ions and anionic diazaheterocyclic ligands (pyrimidinolate and phenylimidazolate) as organic linkers, have been successfully used for the aerobic oxidation of tetralin, yielding α-tetralone (T{double bond, long}O) as the main product. Both materials are stable and recyclable under the reaction conditions. Kinetic studies revealed significant differences between the two MOFs, as a consequence of the different catalytic behavior of their central metal ions. [Cu(2-pymo)2] is highly active for the activation of tetralin to produce tetralinhydroperoxide (T{single bond}OOH), and less efficient in reacting the peroxide. Meanwhile, the use of the cobalt catalyst involves a long induction period for the reaction. However, once T{single bond}OOH is formed, Co2+ rapidly and efficiently transforms this into T{double bond, long}O, with high tetralone-to-tetralol ratio (T{double bond, long}O/T{single bond}OH of ca. 7). The combination of both materials has revealed as a convenient strategy for preparing a highly efficient, selective and reusable catalyst for the liquid phase aerobic oxidation of tetralin.
- Llabres i Xamena,Casanova,Galiasso Tailleur,Garcia,Corma
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p. 220 - 227
(2008/09/20)
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- Solvent-free, heterogeneous photooxygenation of hydrocarbons by Hyflon membranes embedding a fluorous-tagged decatungstate
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Hybrid fluoropolymeric membranes with 25% loading of the fluorous-tagged (RfN)4W10O32 effect the solvent-free photooxygenation of benzylic C-H bonds with up to 6100 TONs in 4 hours. The Royal Society of Chemistry 2006.
- Carraro, Mauro,Gardan, Martino,Scorrano, Gianfranco,Drioli, Enrico,Fontananova, Enrica,Bonchio, Marcella
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p. 4533 - 4535
(2008/09/19)
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- Synthesis of aromatic aldehydes by aerobic oxidation of hydroaromatic compounds and diarylalkanes using N-hydroxyphthalimide (NHPI) as a key catalyst
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Aerobic oxidation of hydroaromatic compounds and diarylalkanes by N-hydroxyphthalimide (NHPI) under mild conditions afforded the corresponding hydroperoxides in high selectivity. Treatment of the resulting hydroperoxides with sulfuric acid followed by neutralization by a base resulted in phenol and aromatic aldehydes in high selectivity. This method provides a convenient synthetic route to aldehydes involving an aromatic moiety.
- Aoki, Yasuhiro,Sakaguchi, Satoshi,Ishii, Yasutaka
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p. 2497 - 2500
(2007/10/03)
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- Kinetic modelling and inverse treatment of the radical mechanism of the liquid-phase autoxidation of 1,2,3,4-tetrahydronaphthalene
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A kinetic model to account for the overall radical mechanism of the self-initiated liquid-phase autoxidation of 1,2,3,4-tetrahydronaphthalene (tetralin: RH2) without solvent and without catalyst at 60°C under normal pressure is presented. The model was constructed following a heuristic approach and it consists of 16 elementary steps and a species space including 6 radical and 7 nonradical compounds. Applying inverse computations, the model can be assigned to experimentally observed data within very good agreement where most of the computed values for the kinetic parameters are found to be close to literature values. The respective experimental data is characterized by an autocatalytic time-evolution of tetralin hydroperoxide (HROOH) and of α-tetralone (RO) where in the first stage of autoxidation a remarkable very slow rate of the RO formation in respect to that of the HROOH formation can be observed. This effect is explicitly expressed by the transformation process of tetralyloxy radicals (HRO·) into α-tetralol radicals (·ROH) which react with oxygen yielding RO. The transformation is suggested to be catalyzed by α-tetralol (HROH) which accumulates autocatalytically during the radical chain process. Hence, the nonlinear formation of HROH leads to a switching in the transformation of HRO· into ·ROH radicals which causes a growing rate of RO evolution. The autocatalytic nature of the overall process is explained by degenerate branching of one molecule of HROOH yielding radical species finally resulting into 2 tetralyl radicals (RH·). This process leads to a growing number of chain propagating reaction sequences involving RH· and tetralylperoxy radicals (HROO·) in which RH2 and O2 are consumed and HROOH is formed. Based on the fitting of experimental data the suggested general dynamic structure of the model is validated by computing the reaction fluxes vs. time of several mechanistic key steps. By computer simulations the model is also shown to predict the increase of product accumulation which can be observed experimentally if the autoxidation of RH2 is started after an initial addition of HROH.
- Lavabre,Micheau,Buhse,Thiemann
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p. 333 - 344
(2007/10/03)
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- Oxidation of activated phenols by dioxygen catalysed by the H5PV2Mo10O40 heteropolyanion
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The H5PV2Mo10O40 heteropolyanion has been found to catalyse the highly selective aerobic oxidation of dialkylphenols to diphenoquinones and the oxidation of 2,3,5-trimethylphenol to the 2,3,5-trimethyl-1,4-benzoquinone. The rate is highly dependent on the oxidation potential of the substrate and is proceeds by electron transfer from the phenol substrate to the heteropolyanion catalyst.
- Lissel,Jansen In De Wal,Neumann
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p. 1795 - 1798
(2007/10/02)
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- Preparation of Oxidation Catalysts by Immobilization and Isolation of Metal Complexes into Monolayer Matrix on Silica Surface
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Immobilization and isolation of cobalt-pyridine complexes in the fence of monolayer matrix on silica surface provided the active catalysts for oxidation of 1,2,3,4-tetrahydronaphthalene
- Miki, Keiji,Sato, Yoshiki
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p. 813 - 816
(2007/10/02)
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- Selective Decomposition of Tetralin Hydroperoxide Catalysed by Quaternary Ammonium Salts
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Tetralin hydroperoxide decomposes to 1-tetralone via a hydrogen bond complex with quaternary ammonium salt catalysts.
- Napadensky, Eduardo,Sasson, Yoel
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- Recognition of Tetralin Hydroperoxide by Cyclodextrins
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The recognition ability of α-, β- and γ-cyclodextrins (CDs) to tetralin hydroperoxide is discussed.CDs formed inclusion complexes more predominantly with tetralin hydroperoxide than with tetralin.The most noticeable specificity was found when β-CD was used as a host.Inclusion complexes of CDs with tetralin were also prepared and their molar ratios were determined.
- Asakura, Kouichi,Tanaka, Nobutoshi,Matsumura, Shuichi,Yoshikawa, Sadao
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p. 1997 - 2000
(2007/10/02)
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- ELECTRON TRANSFER ACTIVATION. HYDROPEROXIDE INTERMEDIATES IN A NOVEL AND SELECTIVE PROCEDURE FOR BENZYLIC OXIDATIONS.
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A selective and mild photochemical procedure for benzylic oxidations with 9,10-dicyanoanthracene (DCA) an usual electron acceptor, in the presence of methyl viologen (MV2+), an electron relay, has been developed.Methyl and methylene groups are oxidized in good to excellent yields to the corresponding hydroperoxides.
- Santamaria, J.,Jroundi, R.,Rigaudy, J.
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p. 4677 - 4680
(2007/10/02)
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- OXIDATION OF 1,2,3,4-TETRAHYDRONAPHTHALENE BY DIOXYGEN. EFFECT OF 3d TRANSITION METAL 2,4-PENTANEDIONATES ON THE THERMAL AND PHOTOINITIATED REACTIONS
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The effects of MnIII, CoII, CoIII, FeIII, and CrIII 2,4-pentanedionates on the thermal and photoinitiated oxidation reactions of 1,2,3,4-tetrahydronaphthalene by dioxygen have been investigated.CoII and MnIII, which are highly efficient catalysts for the thermal reaction, do not increase the rate of the photoinitiated reaction.FeIII and CoIII, which are poorly active in catalyzing the thermal reaction, have profound photocatalytic effects.The catalytic effect of CrIII is critically dependent on the presence of 1,2,3,4-tetrahydro-1-naphthyl hydroperoxide.An increase in the reaction temperature increases the rate of the photoinitiated reaction and enhances the catalytic and photocatalytic effects.
- Lunak, Stanislav,Vaskova, Marie,Veprek-Siska, Josef
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p. 2537 - 2545
(2007/10/02)
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- Absolute rate constants for hydrocarbon autoxidation. 33. A product study of the self-reaction of α-tetralylperoxyls in solution
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The major initial products of the self-reaction of α-tetralylperoxyls (C10H11O2.) in chlorobenzene at 303-353 K are equal concentrations of α-tetralol and α-tetralone in c.a. 90percent yield based on the number of initiating radicals.These yields are consistent with the non-radical (Russell) mechanism for self-reaction.Low concentrations of bis(α-tetralyl) peroxide are produced, indicating that there is a small but detectable free-radical contribution towards termination.C10H11O2. undergoes β-scission in this temperature range but steady-state concentrations of C10H11. are too low to influence the termination rate contant 2k1, or react with C10H11O2. to give (C10H11)2O2. α-Tetralol to α-tetralone ratios and total yields of these products are significantly less than 1 and 100percent, respectively, in methanol and acetonitrile.Formaldehyde is produced in methanol indicating the involvement of α-hydroxymethylperoxyls, derived from the solvent, in termination.There is no evidence for a chain reaction or a zwitterion intermediate for self-reaction of C10H11O2. in solution.
- Baignee, A.,Chenier, J. H. B.,Howard, J. A.
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p. 2037 - 2043
(2007/10/02)
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- Spin Trapping of Peroxy Radicals by Phenyl-N-(tert-butyl)nitrone and Methyl-N-durylnitrone
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The spin trapping of tert-butylperoxy and tetralylperoxy radicals by phenyl-N-(tert-butyl)nitrone (PBN) and methyl-N-durylnitrone (MDN) has been investigated.The peroxy radicals were generated by alkoxy radical induced decomposition of hydroperoxides, hydrogen atom abstraction from hydrocarbon in the presence of oxygen, and decomposition of hydroperoxydes by cobaltous ion and lead tetraacetate.The spin adducts of peroxy radicals were observed by ESR and their hyperfine splitting constants were detrmined.The spin adducts of peroxy radicals by MDN could be clearly distinguished from that of alkoxy radical.The nitrone spin adducts of oxygen radicals were found to be reasonably stable at room temperature in the dark, but they decayed readily in the ordinary laboratory light.
- Niki, Etsuo,Yokoi, Seiichi,Tsuchiya, Jyunichi,Kamiya, Yoshio
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p. 1498 - 1503
(2007/10/02)
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- Dioxygen Transfer from 4a-Hydroperoxyflavin Anion. 2. Oxygen Transfer to the 10 Position of 9-Hydroxyphenanthrene Anions and to 3,5-Di-tert-butylcatechol Anion
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The reaction of the peroxy anion of N5-ethyl-4a-hydroperoxy-3-methyllumiflavin (4a-FlEtO2-) with the anions of 3,5-di-tert-butylcatechol (VIII), 10-ethoxy-9-phenanthrol (Ia), and 10-methyl-9-phenanthrol (Ib) has been investigated.All products may be accountable through the transfer of O2 from the 4a-FlEtO2- reactant to the phenolate anions with the production of reduced flavin anion (FlEt-) and a hydroperoxycyclohexadienone.From VIII- (t-BuOH) there was obtained 3,5-di-tert-butyl-o-quinone (IX) and Ib- yielded (t-BuOH or CH2CN) 10-hydroxy-10-methyl-9,10-dihydro-9-phenanthrone (IIIb), while Ia- provided both 9,10-phenanthrenequinone (V) and monoethyl 1,1'-diphenate (IVa) (the ratio of V:IVa being solvent dependent).The mechanisms for the decomposition of intermediate peroxide anions to products are discussed.The conversion of Ia- to IVa by oxygen transfer from 4a-FlEtO2- amounts to a catalysis by FlEt- of the reaction of 3O2 with Ia and serves as a biomimetic reaction of flavoenzyme dioxygenase.The kinetic for the reaction of VIII- with 4a-FlEtO2- require the formation of an intermediate.Since the rate constants for the reaction of both VIII- and 2,6-di-tert-butyl-4-methylphenolate anion with 4a-FlEtO2- are identical under saturating conditions by these phenolate ions, it is concluded that the intermediate is formed in a unimolecular reaction from 4a-FlEtO2- (k = 0.36 s-) as in eq 19.Dissociation of 4a-FlEtO2- to FlEt-+ O2 and reaction of phenolate ions with O2 may be discounted since the second-order rate constants for the reaction of phenolate ions with O2 are less than required for the kinetic competency of this process.Dissociation of 4a-FlEtO2- to yield neutral flavin radical (FlEt.) + O2-. followed by reduction of FlEt. by fenolate ion to provide FlEt- and phenoxy radical with the coupling of the latter with O2-. is also improbable.Thus, though the second-order rate constants for 1e- reduction of FlEt. by the various phenolate species are sufficiently large to allow the kinetic competency of this step, there exists no evidence that O2-. can couple with any radical species to provide a hydroperoxide.The oxygen-donating intermediate formed from 4a-FlEtO2- is suggested to be the 4a,10-dioxetane (XII) or an oxygen molecule more loosely associated with FlEt-.The equilibrium constant for the formation of such an intermediate may be as small as 10-5 if the rate of reaction of phenolate ion with this species approaches a diffusion-controlled process.
- Muto, Shigeaki,Bruice, Thomas C.
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p. 4472 - 4480
(2007/10/02)
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