Xn:Harmful;590-67-0Relevant articles and documents
Acid-Catalyzed Hydrolysis of Bridged Bi- and Tricyclic Compounds. 25. Comparison of the Hydrations of 2-Methyl-2-norbornene and 2-Methylenenorbornane with Those of 1-Methylcyclohexene and Methylenecyclohexane
Lajunen, Martti,Hiukka, Risto
, p. 1522 - 1525 (1986)
Hydration rates of 2-methyl-2-norbornene, 2-methylenenorbornane, 1-methylcyclohexene, and methylenecyclohexane were measured spectrophotometrically in aqueous perchloric acid.The activation parameters and solvent deuterium isotope effects are in all cases in agreement with the slow proton transfer to an olefinic carbon atom.The free energy diagrams show that the Gibbs energy of the transition state of protonation (hydration) is higher for methylenecycloalkanes than for methylcycloalkenes.The energy difference is small (0.8 kJ mol-1) in the case of the bicyclic olefins and large (11.5 kJ mol-1) in the case of the monocyclic olefins mentioned.Thus, no marked difference in the energies of the transition states caused by a possible distortion of the ?-orbitals of 2-methyl-2-norbornene can be seen in the hydrations of the bicyclic olefins.An explanation for the latter large difference is evidently a change of conformation during the protonation of 1-methylcyclohexene, which possibly also causes an exceptionally low isotope effect (kH/kD=1.13).
Products of ozone oxidation of some saturated cyclic hydrocarbons
Khalitova,Grabovskiy,Antipin,Spirikhin,Kabal'Nova
, p. 1710 - 1716 (2015)
Low-temperature ozone oxidation of a series of saturated carbocyclic hydrocarbons afforded the corresponding alcohols and/or ketones in high yield through intermediate trioxidanes. exo,endo-Tetracyclo-[6.2.1.03,5]undecane-2,7-dione and exo,endo,endo-hexacyclo[9.3.1.03,8.04,6.05,9.012,14]pentadecane-2,10-dione were isolated, and exo,endo,exo-pentacyclo[6.3.1.02,7.03,5.09,11]dodecyl-, exo,exo,exo-heptacyclo-[9.3.1.02,10.03,8.04,6.05,9.012,14]pentadecyl, and 1-methylcyclohexyltrioxidanes were identified and characterized for the first time.
Hydrogen-atom and oxygen-atom transfer reactivities of iron(
Banerjee, Sridhar,Haukka, Matti,Hossain, Md. Kamal,Huelsmann, Ricardo Dagnoni,Martendal, Edmar,Munshi, Sandip,Nordlander, Ebbe,Paine, Tapan K.,Peralta, Rosely,Singh, Reena,Sinha, Arup,Valiati, Andrei Felipe,Wendt, Ola F.,Xavier, Fernando,Yiga, Solomon
supporting information, p. 870 - 884 (2022/02/01)
A series of iron(ii) complexes with the general formula [FeII(L2-Qn)(L)]n+ (n = 1, L = F?, Cl?; n = 2, L = NCMe, H2O) have been isolated and characterized. The X-ray crystallographic data reveals that
Deciphering Reactivity and Selectivity Patterns in Aliphatic C-H Bond Oxygenation of Cyclopentane and Cyclohexane Derivatives
Martin, Teo,Galeotti, Marco,Salamone, Michela,Liu, Fengjiao,Yu, Yanmin,Duan, Meng,Houk,Bietti, Massimo
supporting information, p. 9925 - 9937 (2021/06/30)
A kinetic, product, and computational study on the reactions of the cumyloxyl radical with monosubstituted cyclopentanes and cyclohexanes has been carried out. HAT rates, site-selectivities for C-H bond oxidation, and DFT computations provide quantitative information and theoretical models to explain the observed patterns. Cyclopentanes functionalize predominantly at C-1, and tertiary C-H bond activation barriers decrease on going from methyl- and tert-butylcyclopentane to phenylcyclopentane, in line with the computed C-H BDEs. With cyclohexanes, the relative importance of HAT from C-1 decreases on going from methyl- and phenylcyclohexane to ethyl-, isopropyl-, and tert-butylcyclohexane. Deactivation is also observed at C-2 with site-selectivity that progressively shifts to C-3 and C-4 with increasing substituent steric bulk. The site-selectivities observed in the corresponding oxidations promoted by ethyl(trifluoromethyl)dioxirane support this mechanistic picture. Comparison of these results with those obtained previously for C-H bond azidation and functionalizations promoted by the PINO radical of phenyl and tert-butylcyclohexane, together with new calculations, provides a mechanistic framework for understanding C-H bond functionalization of cycloalkanes. The nature of the HAT reagent, C-H bond strengths, and torsional effects are important determinants of site-selectivity, with the latter effects that play a major role in the reactions of oxygen-centered HAT reagents with monosubstituted cyclohexanes.
Cationic nickel(II) pyridinophane complexes: Synthesis, structures and catalytic activities for C-H oxidation
Nishimura, Tsubasa,Ando, Yuki,Shinokubo, Hiroshi,Miyake, Yoshihiro
supporting information, p. 1049 - 1052 (2021/05/19)
A series of nickel(II) pyridinophane complexes were synthesized and characterized by X-ray crystallographic analysis. Their IR spectra supported the existence of mononuclear nickel(II) complexes in solution. Furthermore, we conducted catalytic CH oxidation of cyclooctane with nickel(II) pyridinophanes as the catalysts. The activity of nickel(II) pyridinophanes was affected by steric hindrance around the nitrogen atoms.
Aliphatic C–H hydroxylation activity and durability of a nickel complex catalyst according to the molecular structure of the bis(oxazoline) ligands
Hikichi, Shiro,Izumi, Takashi,Matsuba, Naki,Nakazawa, Jun
, (2021/07/13)
Applicability of the oxazoline-based compounds, bis(2-oxazolynyl)methane (BOX) and 2,6-bis(2-oxazolynyl)pyridine (PyBOX), as supporting ligands of nickel(II) complexes for the catalysis of aliphatic C–H hydroxylation with m-CPBA (meta-chloroperoxybenzoic acid) was explored. Substituent groups at the fourth and fifth positions of oxazoline rings and the bridgehead carbon atom of the BOX derivatives affected the catalytic performances toward cyclohexane hydroxylation. Presence of dioxygen led to a reduced catalytic performance of the nickel complexes, except in the case of a fully substituted BOX ligand complex.
Efficient alkane hydroxylation catalysis of nickel(ii) complexes with oxazoline donor containing tripodal tetradentate ligands
Hikichi, Shiro,Horii, Sena,Nakazawa, Jun,Okamura, Masaya,Terao, Ikumi
, p. 6108 - 6118 (2020/05/25)
Tris(oxazolynylmethyl)amine TOAR(where R denotes the substituent groups on the fourth position of the oxazoline rings) complexes of nickel(ii) have been synthesized as catalyst precursors for alkane oxidation withmeta-chloroperoxybenzoic acid (m-CPBA). The molecular structures of acetato, nitrato,meta-chlorobenzoato and chlorido complexes with TOAMe2have been determined using X-ray crystallography. The bulkiness of the substituent groups R affects the coordination environment of the nickel(ii) centers, as has been demonstrated by comparison of the molecular structures of chlorido complexes with TOAMe2and TOAtBu. The nickel(ii)-acetato complex with TOAMe2is an efficient catalyst precursor compared with the tris(pyridylmethyl)amine (TPA) analogue. Oxazolynyl donors’ strong s-electron donating ability will enhance the catalytic activity. Catalytic reaction rates and substrate oxidizing position selectivity are controlled by the structural properties of the R of TOAR. Reaction of the acetato complex with TOAMe2andm-CPBA yields the corresponding acylperoxido species, which can be detected using spectroscopy. Kinetic studies of the decay process of the acylperoxido species suggest that the acylperoxido species is a precursor of an active species for alkane oxidation.
Homogeneous catalytic oxidation of alkenes employing mononuclear vanadium complex with hydrogen peroxide
Maurya, Abhishek
, p. 3261 - 3269 (2020/07/14)
Abstract: Homogeneous liquid-phase oxidation of alkenes (allylbenzene, cis-cyclooctene, 4-chlorostyrene, styrene, 2-norbornene, 1-methyl cyclohexene, indene, lemonine, and 1-hexene) were catalyzed by using vanadium complex [VO(hyap)(acac)2] in existence of H2O2. The complex [VO(hyap)(acac)2] was formed as a crystal by the reaction of [VO(acac)2] and 2-hydroxyacetophenone (hyap) in the presence of methanol by refluxing the reaction mixture. Various analytical and spectroscopic techniques, namely FTIR, ESI–MS, UV–Vis, single-crystal XRD, and EPR, were used to analyze and optimize the structure of the complexes. Graphic abstract: [Figure not available: see fulltext.].
Highly Selective and Catalytic Oxygenations of C?H and C=C Bonds by a Mononuclear Nonheme High-Spin Iron(III)-Alkylperoxo Species
Ghosh, Ivy,Banerjee, Sridhar,Paul, Satadal,Corona, Teresa,Paine, Tapan Kanti
, p. 12534 - 12539 (2019/08/07)
The reactivity of a mononuclear high-spin iron(III)-alkylperoxo intermediate [FeIII(t-BuLUrea)(OOCm)(OH2)]2+(2), generated from [FeII(t-BuLUrea)(H2O)(OTf)](OTf) (1) [t-BuLUrea=1,1′-(((pyridin-2-ylmethyl)azanediyl)bis(ethane-2,1-diyl))bis(3-(tert-butyl)urea), OTf=trifluoromethanesulfonate] with cumyl hydroperoxide (CmOOH), toward the C?H and C=C bonds of hydrocarbons is reported. 2 oxygenates the strong C?H bonds of aliphatic substrates with high chemo- and stereoselectivity in the presence of 2,6-lutidine. While 2 itself is a sluggish oxidant, 2,6-lutidine assists the heterolytic O?O bond cleavage of the metal-bound alkylperoxo, giving rise to a reactive metal-based oxidant. The roles of the urea groups on the supporting ligand, and of the base, in directing the selective and catalytic oxygenation of hydrocarbon substrates by 2 are discussed.
Metal-Organic Architectures Assembled from Multifunctional Polycarboxylates: Hydrothermal Self-Assembly, Structures, and Catalytic Activity in Alkane Oxidation
Gu, Jinzhong,Wen, Min,Cai, Yan,Shi, Zifa,Arol, Aliaksandr S.,Kirillova, Marina V.,Kirillov, Alexander M.
, p. 2403 - 2412 (2019/02/28)
A three-component aqueous reaction system comprising copper(II) acetate (metal node), poly(carboxylic acid) with a phenylpyridine or biphenyl core (main building block), and 1,10-phenanthroline (crystallization mediator) was investigated under hydrothermal conditions. As a result, four new coordination compounds were self-assembled, namely, {[Cu(μ3-cpna)(phen)]·H2O}n (1), {[Cu(μ-Hbtc)(phen)]·H2O}n (2), {[Cu(μ3-Hcpic)(phen)]·2H2O}n (3), and [Cu6(μ-Hcptc)6(phen)6]·6H2O (4), where H2cpna = 5-(2′-carboxylphenyl)nicotinic acid, H3btc = biphenyl-2,4,4′-tricarboxylic acid, H3cpic = 4-(5-carboxypyridin-2-yl)isophthalic acid, H3cptc = 2-(4-carboxypyridin-3-yl)terephthalic acid, and phen = 1,10-phenanthroline. Crystal structures of compounds 1-3 reveal that they are 1D coordination polymers with a ladder, linear, or double-chain structure, while product 4 is a 0D hexanuclear complex. All of the structures are extended further [1D a?' 2D (1 and 2), 1D a?' 3D (3), and 0D a?' 3D (4)] into hydrogen-bonded networks. The type of a multicarboxylate building block has a considerable effect on the final structures of 1-4. The magnetic behavior and thermal stability of 1-4 were also investigated. Besides, these copper(II) derivatives efficiently catalyze the oxidation of cycloalkanes with hydrogen peroxide under mild conditions. The obtained products are the unique examples of copper derivatives that were assembled from H2cpna, H3btc, H3cpic, and H3cptc, thus opening up their use as multicarboxylate ligands toward the design of copper-organic architectures.
