Xn:Harmful;
108-93-0Relevant articles and documents
Selective catalysis of the aerobic oxidation of cyclohexane in the liquid phase by carbon nanotubes
Yu, Hao,Peng, Feng,Tan, Jun,Hu, Xiaowei,Wang, Hongjuan,Yang, Jian,Zheng, Wenxu
, p. 3978 - 3982 (2011)
Putting the N in nanotube: Carbon nanotubes (CNTs) catalyze the aerobic oxidation of cyclohexane into cyclohexanol, cyclohexanone, and adipic acid with excellent activity and controllable selectivity. The catalytic activity is further enhanced by nitrogen dopants in the nanotube (see diagram; AC=activated carbon, MWCNT=multiwalled CNT, N-CNT=nitrogen-doped CNT).
Studies on -Catalysed Homogeneous Transfer Hydrogenation Reactions; X-Ray Structure of
Bhaduri, Sumit,Sapre, Niteen,Sharma, Krishna,Jones, Peter G.,Carpenter, Gene
, p. 1305 - 1311 (1990)
Using (1) as the homogeneous precatalyst, transfer hydrogenations of cyclohex-2-en-1-one, benzylideneaniline, and carbon tetrahalides by donor alcohols, in particular propan-2-ol, have been studied.Conversion of cyclohex-2-en-1-one into cyclohexanol has been found to proceed via the intermediate formation of cyclohexanone.From the temperature dependence of the overall reaction rates, the precatalysts and are involved in processes with comparable activation energies.Two catalytically active cluster complexes, and , were isolated from the reaction of (1) with cyclohex-2-en-1-one.Hydrogenation of the tetranuclear cluster led to the formation of and .The reaction of the complex (1) with benzylideneaniline gave a catalytically active cluster .With (1) as the precatalyst, analogues of benzylideneaniline of general formula RC6H4CH=NPh can all be transfer hydrogenated, with the exception of the o-methoxy derivative.The complex was found to undergo reversible carbonylation.Rational syntheses for and were designed by treating (1) with the appropriate alcohol and carbon tetrahalide.The X-ray structure of has been determined.The halogenoalkoxo clusters are considered to be active intermediates in the overall catalytic cycle for the transfer hydrogenations of carbon tetrahalides.
Hydration of cyclohexene in sub-critical water over WOx-ZrO 2 catalysts
Yuan, Pei-Qing,Liu, Ying,Bai, Fan,Xu, Liang,Cheng, Zhen-Min,Yuan, Wei-Kang
, p. 753 - 756 (2011)
WOx/ZrO2 catalyzed hydration of cyclohexene in sub-critical water was experimentally investigated. The migration of reaction zone into sub-critical water makes it possible to run the hydration in a single liquid phase, and the reaction is free from the limitation of liquid-liquid phase mass transfer to hydration kinetics. The severe hydrothermal environments favor the transformation of surface active sites on WOx-ZrO 2 catalysts to Br?nsted acid centers of stronger acidity, which are highly effective for the hydration of cyclohexene to the desired product cyclohexanol.
The effect of metal (Nb, Ru, Pd, Pt) supported on SBA-16 on the hydrodeoxygenation reaction of phenol
Feliczak-Guzik, Agnieszka,Szczyglewska, Paulina,Nowak, Izabela
, p. 61 - 67 (2019)
Ordered silica materials of SBA-16 type were synthesized, characterized as to their physicochemical properties and used as supports of the active phases which were niobium, ruthenium, palladium or platinum ions. Physicochemical properties of the systems o
Fe(TPA)-catalyzed alkane hydroxylation. Metal-based oxidation vs radical chain autoxidation
Kim, Jinheung,Harrison, Roger G.,Kim, Cheal,Que Jr., Lawrence
, p. 4373 - 4379 (1996)
Catalytic alkane functionalization by the Fe(TPA)/(t)BuOOH system (with [Fe(TPA)Cl2]+ (1), [Fe(TPA)-Br2]+ (2), and [Fe2O(TPA)2(H2O)2]4+ (3) as catalysts; TPA = tris(2-pyridylmethyl)amine) has been investigated in further detail to clarify whether the reaction mechanism involves a metal- based oxidation or a radical chain autoxidation. These two mechanisms can be distinguished by the nature of the products formed, their dependence on O2 (determined from argon purge and 18O2 labeling experiments), and the kinetic isotope effects associated with the products. The metal-based oxidation mechanism is analogous to heme-catalyzed hydroxylations and would be expected to produce mostly alcohol with a large kinetic isotope effect. The radical chain autoxidation mechanism entails the trapping of substrate alkyl radicals by O2 to afford alkylperoxy radicals that decompose to alcohol and ketone products in a ratio 1:1 or smaller via Russell termination steps. Consistent with the latter mechanism, alcohol and ketone products were observed in a ratio of 1:1 or less, when catalysts 1, 2, or 3 were reacted with alkane and 150 equiv of (t)BuOOH; these product yields were diminished by argon purging, demonstrating the participation of O2 in the reaction. However, when the 3-catalyzed oxidation was carried out in the presence of a limited (20 equiv) amount of (t)BuOOH or CmOOH, the sole product observed was alcohol; k(H)/k(D) values of 10 were observed, consistent with a metal- based oxidation. To reconcile these apparently conflicting results, a mechanistic scheme is proposed involving the formation of an alkylperoxyiron(III) intermediate which can oxidize either the substrate (metal-based oxidation) or excess ROOH (to generate alkylperoxy radicals that initiate a radical chain autoxidation process), the relative importance of the two mechanisms being determined by the concentration of ROOH.
Highly Active and Selective RuPd Bimetallic NPs for the Cleavage of the Diphenyl Ether C-O Bond
Guo, Miao,Peng, Juan,Yang, Qihua,Li, Can
, p. 11174 - 11183 (2018)
The cleavage of C-O linkages of aryl ethers into aromatic platform compounds is a challenging reaction but of great importance for the sustainable future. Herein, we reported the efficient H2-assisted C-O bond cleavage of diphenyl ether (DPE) in aqueous phase over ultrasmall RuPd bimetallic nanoparticles (NPs) supported on amine-rich silica hollow nanospheres (NH2-SiO2). RuPd5/NH2-SiO2 with TOF of 172 h-1 and C-O cleavage selectivity of 99% outperformed the corresponding monometallic counterparts and is among the most active solid catalysts for C-O bond cleavage of DPE. The control experiments and characterization results showed that the effective isolation of Ru sites and optimized H2 dissociation ability mainly contributed to the enhanced catalytic performance of RuPd bimetallic NPs, in which Ru and Pd worked cooperatively with Ru sites for DPE activation and Pd sites for H2 dissociation. The alloying of two or multiple metal atoms provides an efficient approach for designing high-performance catalysts for chemical transformations.
Oxidation of Cycloalkanes and Arylalkanes with Sodium Periodate Catalysed by Manganese Porphyrins
Mohajer, Daryoush,Tayebee, Reza,Goudarziafshar, Hameed
, p. 822 - 823 (1998)
Cycloalkanes and arylalkanes are transformed into their related alcohols and ketones in moderate to high yields and selectivities at room temperature with sodium periodate in the presence of manganese(III tetraarylporphyrin complexes associated with imidazole and tetra-n-butylammonium bromide in CH2Cl2-H2O solution.
Synthesis, characterization and heterogeneous catalytic application of copper integrated mesoporous matrices
Das, Swapan K.,Mukherjee, Sanghamitra,Lopes, Luis M. F.,Ilharco, Laura M.,Ferraria, Ana M.,Botelho Do Rego, Ana M.,Pombeiro, Armando J. L.
, p. 3215 - 3226 (2014)
Ordered copper integrated mesoporous silicate catalysts (CuMSC) have been synthesized by the utilization of the amphiphilic tri-block copolymer pluronic F127 as a structure directing agent (SDA) under acidic aqueous conditions. The mesophase of the materials was investigated using small-angle powder X-ray diffraction and transmission electron microscopic (TEM) image analysis. N 2 adsorption-desorption studies show that the BET surface area of CuMSC (214-407 m2 g-1) is lower than that of pure silica (611 m2 g-1) and has smaller average pore dimensions (4.0-5.0 nm), both prepared following the same synthetic route. The reduction of pore size and surface area points to incorporation of copper within the silicate network. FEG-SEM results suggest that the materials have a plate-like morphology and are composed of very tiny nanoparticles. EDS surface chemical analysis was utilized for the detection of the distribution of Si, O and Cu in the matrix. The FT IR spectral study suggests the complete removal of the surfactants from the calcined materials and the presence of Si-O-Cu bonds for high nominal contents. X-ray photoelectron spectroscopy (XPS) and UV-vis reflectance spectra show the oxidation state of copper and coordination mode, respectively. These mesoporous materials display a good catalytic activity in the oxidation of cyclohexane to cyclohexanone and cyclohexanol in the presence of the green oxidant hydrogen peroxide. The maximum yield (cyclohexanone and cyclohexanol) was ca. 29% and the TON (turnover number) was 276 under optimal reaction conditions. The good catalytic activity could be attributed to the large surface area and the presence of a high number of active sites located at the surface of the material, as well as to its stability. The catalysts showed negligible loss of activity after five cycles.
Photooxidation of Hydrocarbons on Porphyrin-modified Titanium Dioxide Powders
Amadelli, R.,Bregola, M.,Polo, E.,Carassiti, V.,Maldotti, A.
, p. 1355 - 1357 (1992)
A composite catalyst consisting of an iron porphyrin covalently linked to TiO2 shows a new reactivity in the photochemical mono-oxygenation of hydrocarbons under mild conditions, with respect to the porphyrin and TiO2 used separately.
Vapor-phase catalytic dehydration of terminal diols
Abe, Katsutoshi,Ohishi, Yusuke,Okada, Takuto,Yamada, Yasuhiro,Sato, Satoshi
, p. 419 - 424 (2011)
Vapor-phase catalytic reactions of several terminal diols were investigated over several rare earth oxides, such as Sc2O3, Y 2O3, CeO2, Yb2O3, and Lu2O3. Sc2O3 showed selective catalytic activity in the dehydration of terminal diols with long carbon chain, such as 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, and 1,12-dodecanediol, to produce the corresponding unsaturated alcohols. In the dehydration of 1,6-hexanediol, 5-hexen-1-ol was produced with selectivity over 60 mol%, together with by-products such as ε-caprolactone and oxacycloheptane. In the dehydration of 1,10-decanediol, 9-decen-1-ol was produced with selectivity higher than 70 mol%. In addition to Sc 2O3, heavy rare earth oxides such as Lu2O 3 as well as monoclinic ZrO2 showed moderate selectivity in the dehydration of the terminal diols.
