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.
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
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.
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.
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Kohler, Thompson
, p. 3822 (1933)
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Supported nickel catalysts for anisole hydrodeoxygenation: Increase in the selectivity to cyclohexane
Vargas-Villagrán,Flores-Villeda,Puente-Lee,Solís-Casados,Gómez-Cortés,Díaz-Guerrero,Klimova
, p. 26 - 41 (2020)
The hydrodeoxygenation (HDO) of anisole was performed with Ni catalysts supported on SBA-15 silica and protonated titanate nanotubes (PTN), in order to determine the effect of the support's nature and the method of incorporation of Ni species on the catalytic activity and selectivity in HDO. Catalysts with 10 wt.percent of Ni were prepared by two methods: deposition-precipitation with urea (DP) and the classical incipient wetness impregnation (IM). Characterization of the catalysts was performed by nitrogen physisorption, temperature programmed reduction, temperature programmed desorption of ammonia, high resolution transmission electron microscopy, scanning electron microscopy, powder X-ray diffraction, XPS and O2 chemisorption. The obtained results show that the support's nature and the preparation method had a strong influence on the dispersion of the supported Ni species and their HDO performance. Catalysts with larger metallic Ni particles showed higher ability for hydrogenation of anisole and higher intrinsic activity (TOF) than those with smaller Ni particles. On the other side, the use of the PTN support and the DP with urea preparation method resulted in catalysts with increased acidity and improved selectivity for the formation of deoxygenated products (cyclohexane).
The effect of oxalic acid and glyoxal on the VO(acac)2-catalyzed cyclohexane oxidation with H2O2
Pokutsa, Alexander,Kubaj, Yulia,Zaborovskyi, Andriy,Maksym, Dariya,Muzart, Jacques,Sobkowiak, Andrzej
, p. 190 - 194 (2010)
A new protocol for the effective oxidation of cyclohexane in acetonitrile at 40 °C and atmospheric pressure into cyclohexanol, cyclohexanone and cyclohexyl hydroperoxide using hydrogen peroxide as the oxidant, vanadyl(IV)-acetylacetonate as the catalyst, oxalic acid and glyoxal as additives is presented with some reaction mechanism proposals.
Synthesis, characterization and catalytic performance in cyclohexane transformation by Bi2O3/MCM-41 nanocomposite materials
Mozaffari, Majid,Ebadi, Amin
, p. 1643 - 1651 (2017)
The nanoparticles of Bi2O3 supported on mesoporous MCM-41 were prepared in a simple way and were well characterized. The oxidation of cyclohexane to cyclohexanol and cyclohexanone under 1 atmospheric pressure of air in the absence of any solvent and reducing agents with Bi2O3/MCM-41 nanocomposites were considered. These nanoparticles of Bi2O3 supported on mesoporous MCM-41 were found to be the very effective catalysts for cyclohexane oxidation with air in a temperature range of 280–370 ?C. The influences of reaction temperature, the loading amount of Bi2O3 and space velocity on the oxidation of cyclohexane were also studied, and optimized conditions were investigated.
Copper ion substituted hercynite (Cu0.03Fe0.97Al 2O4): A highly active catalyst for liquid phase oxidation of cyclohexane
Mistri, Rajib,Maiti, Sayantani,Llorca, Jordi,Dominguez, Montserrat,Mandal, Tapas Kumar,Mohanty, Paritosh,Ray, Bidhan Chandra,Gayen, Arup
, p. 40 - 50 (2014)
Copper ion substituted MAl2O4 (M = Mg, Mn, Fe, Ni and Zn) spinels, CuxM1-xAl2O4 (x = 0.03 and 0.05), have been synthesized by a single step solution combustion method. Of the various compositions studied the 3 at.% copper ion substituted hercynite, Cu0.03Fe0.97Al2O4, reported here for the first time, is shown to be much more active (～92% conversion with ～99% selectivity) than other spinel analogues towards liquid phase oxidation of cyclohexane in acetonitrile with H2O2 as oxidant in air. Powder XRD analyses have revealed formation of pure hercynite phases. The least-square refined lattice parameters obtained from XRD data together with microstructural data by HRTEM have indicated copper ion substitution in the spinel lattice. The oxidation state of copper has been established as +2 from XPS analysis and it seem to be primarily substituted in the Fe-site of hercynite. Incorporation of the copper in the spinel structure of FeAl 2O4 leading to an ionic interaction is explained to be responsible for the higher oxidation activity observed over the combustion synthesized catalyst than the corresponding impregnated catalyst which contains finely dispersed CuO crystallites. Effect of recycling (repeated thrice) has shown almost no degradation of activity of the copper ion substituted hercynite. In contrast, the analogous impregnated catalyst has shown appreciable loss of activity in the consecutive cycles due to the presence of dispersed CuO crystallites which can agglomerate with ease and subsequently leach out.
Cyclohexane Functionalization Catalyzed by Octahedral Molecular Sieve (OMS-1) Materials
Wang, Jin-Yun,Xia, Guan-Guang,Yin, Yuan-Gen,Suib, Steven L.,O'Young
, p. 275 - 284 (1998)
Both the abundance of alkanes and their extremely low activity have greatly interested several researchers. In this paper, different metal substituted 3×3 octahedral molecular sieves (OMS-1) materials were used to catalyze the functionalization of cyclohexane by using tert-butyl hydroperoxide as oxidant and tert-butyl alcohol as solvent at different temperatures (60, 80, and 100°C). [Fe]-OMS-1 at 80°C exhibits the best activity and selectivity. The solvent t-butyl alcohol (the reduced state of t-butyl hydroperoxide) was first introduced to the reaction system which makes the system simple to study. The effects of catalyst amount and ratio of tert-butyl alcohol to cyclohexane were examined. Variable speed stirring (200-800 rpm) experiments suggest that under conditions reported here that diffusion is not a problem. Studies of the liquid phase after separation from the solid OMS-1 catalysts have shown that metal does not leach into the solution and that heterogeneous catalysis occurs. At 80°C, the conversion of cyclohexane or the total yield of products can reach 13.1% in 40 h. The yields of cyclohexanone, cyclohexanol, and cyclohexyl hydroperoxide were 6.57,2.83, and 1.38%, respectively, and t-butyl cyclohexyl perether was 2.36%. The reaction conditions are mild, and the catalysts retain their crystallinity after reaction. Moreover, the catalyst can be easily separated from the reaction mixture and used catalysts retain similar catalytic activity over a 40-h time period.
Hydrocarbon Oxidations with Hydrogen Peroxide Catalyzed by a Soluble Polymer-Bound Manganese(IV) Complex with 1,4,7-Triazacyclononane
Nizova, Galina V.,Bolm, Carsten,Ceccarelli, Simona,Pavan, Chiara,Shul'pin, Georgiy B.
, p. 899 - 905 (2002)
Soluble manganese(IV) complexes with polymer-bound 1,4,7-triazacyclononanes as ligands (compound 2) catalyze the oxidation of alkanes by hydrogen peroxide in acetonitrile at room and lower temperatures. The corresponding alkyl hydroperoxides are the main products. The presence of a relatively small amount of acetic acid is obligatory for this reaction. The oxidation of alkanes and olefins exhibits some features (kinetic isotope effect, bond selectivities) that distinguish this system from an analogous one based on the dinuclear Mn(IV) complex 1.
Generation and Chemistry of Cyclohexyloxy Radicals
Druliner, J. D.,Krusic, P. J.,Lehr, G. F.,Tolman, C. A.
, p. 5838 - 5845 (1985)
In this paper we report our work on cyclohexyloxy radicals from dicyclohexyl hyponitrite (CyON2OCy) and the related CyO sources dicyclohexyl peroxydicarbonate and dicyclohexyl peroxide (CyO2Cy), including the 13C and 1H NMR spectra of the radical sources, the kinetics of the DCHN decomposition over a wide range of temperature (followed by both UV and chemiluminescence), ESR spin-trapping studies, the kinetics of hydrogen atom abstraction from a variety of substrates by CyO, and the effect of CyO radical source on product composition.We have also investigated the effects of dissolved O2 on DCHN decomposition in cyclohexane and comment on the source of the observed chemiluminescence.
Morphology-Reserved Synthesis of Discrete Nanosheets of CuO?SAPO-34 and Pore Mouth Catalysis for One-Pot Oxidation of Cyclohexane
Chen, Zhaoxu,Ding, Weiping,Guo, Xiangke,Guo, Xuefeng,Lin, Ming,Peng, Luming,She, Minyi,Shi, Taotao,Xu, Mengxia,Zhu, Yan
, p. 2606 - 2611 (2020)
Discrete nanosheets of silicon-doped AlPO4 molecular sieves (SAPO-34) with a thickness of ≈7 nm have been prepared through morphology-reserved synthesis with a lamellar aluminum phosphate as precursor. Cages of the nanosheets are in situ incorporated with copper oxide clusters. The CuO?SAPO-34 nanosheets exhibit a large external surface area with a high number of (010) channel pores on the surface. Due to the thin morphology, copper oxide clusters occupy the outmost cages with a probability >50 %. The distinctive configuration facilitates a new concept of pore mouth catalysis, i.e., reactant molecules larger than the pores cannot enter the interior of the molecular sieves but can interact with the CuO clusters at “the mouth” of the pore. In heterogeneous catalysis, CuO?SAPO-34 nanosheets have shown top performance in one-pot oxidation of cyclohexane to adipic acid by O2, a key compound for the manufacture of nylon-66, which is so far produced using non-green nitric acid oxidation.
Liquid-phase oxidation of cyclohexane to cyclohexanone over cobalt-doped SBA-3
Liu, Xiaochen,He, Jiao,Yang, Lijun,Wang, Yunan,Zhang, Shihong,Wang, Wei,Wang, Jiaqiang
, p. 710 - 714 (2010)
Liquid-phase oxidation of cyclohexane was carried out under mild reaction conditions over mesoporous Co/SBA-3 catalyst using aqueous hydrogen peroxide (30%) as oxidant and acetic acid as solvent without adding any initiator. The catalyst exhibited high substrate conversion (91.6%) and reasonable product (cyclohexanone) selectivity (64.3%). Fast hot catalyst filtration experiment proved that the catalyst acted as a heterogeneous one and it can be reused two times without losing its activity to a greater extent.
Continuous hydrogenation of hydroquinone to 1,4-cyclohexanediol over alkaline earth metal modified nickel-based catalysts
Bai, Guoyi,Li, Fei,Fan, Xinxin,Wang, Yalong,Qiu, Mande,Ma, Zheng,Niu, Libo
, p. 126 - 130 (2012)
Effects of different alkaline earth metals (Mg, Ca, Sr) on the nickel-based catalysts for the continuous hydrogenation of hydroquinone were studied, and it was found that the by-products, characterized by GC-MS analysis, were mainly composed of phenol and cyclohexanol. The conversion of hydroquinone was 99.2% and the selectivity to 1,4-cyclohexanediol was above 96.7% over a Ni-Sr/γ-Al2O3 catalyst at 160°C and 2.0 MPa hydrogen pressure. The high selectivity of the Ni-Sr/γ-Al 2O3 catalyst was ascribed to its weak acidity due to the formation of SrCO3, confirmed from XRD and NH3-TPD characterizations. Moreover, it was proposed that SrCO3 can disperse and stabilize the active Ni species, making the catalyst stable during the 90 h service life test.
Metal chlorides-catalyzed selective oxidation of cyclohexane by molecular oxygen under visible light irradiation
Wu, Wenfeng,He, Xiangling,Fu, Zaihui,Liu, Yachun,Wang, Yanlong,Gong, Xinglang,Deng, Xiaolin,Wu, Haitao,Zou, Yanhong,Yu, Ningya,Yin, Dulin
, p. 6 - 12 (2012)
The development of mild and efficient process for the selective oxidation of organic compounds with molecular oxygen can be one of the key technologies for synthesizing oxygenates. Here, a visible light-driven metal chloride to catalyze the selective oxidation of cyclohexane was carried out at ambient temperature under a pure O2 atmosphere. Among the metal salts examined, only a few metal chlorides, with easily changeable valence, such as CuCl2·2H2O, VOCl3, and FeCl 3·6H2O, were found to be active to this photo-oxidation reaction in acetonitrile or acetone, providing cyclohexanol, cyclohexanone, chlorocyclohexane, and cyclohexene as main products. This is likely because the weak coordination of these metal chlorides with solvent molecules plays key roles in absorbing visible light and realizing photoredox cycle, as supported by UV-Vis spectrum and cyclic voltammetry measurements. Among these active metal chlorides, CuCl2·2H2O showed a higher conversion and better selectivity for cyclohexanol and cyclohexanone (the oxygenated products) than the other two metal chlorides, and its activity and selectivity for chlorocyclohexane were significantly improved in the case of adding concentrated HCl, because HCl promotes the photocatalytic cycling, as supported by UV-Vis spectra. Notably, a high turnover frequency (TOF, 7.4 h-1) and an excellent selectivity for the oxygenated products (93%) were achieved upon a low concentration of CuCl 2·2H2O (0.002 mol L-1), 0.1 ml of concentrated HCl and 2 atm of O2 pressure. Based on these findings, a free radical mechanism for the present photocatalysis system was proposed.
Ordered macroporous Co3O4-supported Ru nanoparticles: A robust catalyst for efficient hydrodeoxygenation of anisole
Wang, An,Shi, Yisheng,Yang, Lan,Fan, Guoli,Li, Feng
, (2021)
A three-dimensional ordered macroporous Co3O4 (OM-Co3O4) supported Ru catalyst was developed for the efficient hydrodeoxygenation (HDO) of anisole. It is revealed that small-sized Ru nanoparticles evenly distributed over the surface of OM-Co3O4 with large quantities of oxygen vacancies could strongly capture Ru0 species, thereby resulting in strong Ru-Co3O4 interactions. Compared with commercial Co3O4 supported Ru catalyst, Ru/OM-Co3O4 displays a better catalytic HDO performance, with a high cyclohexane yield of 92.4% at 250 °C and 0.5 MPa hydrogen pressure after 5 h on stream. Such a significant efficiency of Ru/OM-Co3O4 is mainly attributed to both high dispersion of Ru0 species and an enhanced formation of surface defects, as well as the unique macroporous framework of OM-Co3O4 support.
Pd@MIL-101 as an efficient bifunctional catalyst for hydrodeoxygenation of anisole
Ren, Hangxing,Li, Chuang,Yin, Dongdong,Liu, Jinxuan,Liang, Changhai
, p. 85659 - 85665 (2016)
A series of highly porous acidic metal-organic framework MIL-101 supported Pd nanoparticles materials with different Pd contents were prepared through a simple sol-gel method. The obtained heterogeneous catalytic material Pd@MIL-101 was comprehensively characterized by powder X-ray diffraction (PXRD), N2 adsorption, FTIR spectroscopy of pyridine adsorption (Py-IR) and transmission electron microscopy (TEM). The intact crystallinity of MIL-101 was found before and after the Pd loading process, and Pd nanoparticles with diameter of 2-3.5 nm were found homogeneously dispersed in MIL-101. The bifunctional Pd@MIL-101 catalyst exhibits good activity in hydrodeoxygenation (HDO) of anisole. It has been shown that the reaction temperature and the Pd content play important roles in the activity toward oxygen-removal. The catalyst after reaction at a high temperature of 240 °C revealed that the Pd nanoparticles tended to migrate to the external surface of the MOF materials and form larger aggregates.
Catalytic hydroxylation in biphasic systems using CYP102A1 mutants
Maurer, Steffen C.,Kuehnel, Katja,Kaysser, Leonard A.,Eiben, Sabine,Schmid, Rolf D.,Urlacher, Vlada B.
, p. 1090 - 1098 (2005)
Cytochrome P450 monooxygenases are biocatalysts that hydroxylate or epoxidise a wide range of hydrophobic organic substrates. Their technical application is, however, limited to a small number of whole-cell processes. The use of the isolated P450 enzymes is believed to be impractical due to their low stability, stoichiometric need of the expensive cofactor NAD(P)H and low solubility of most substrates in aqueous media. We investigated the behaviour of an isolated bacterial monooxygenase (mutants of CYP102A1) in a biphasic reaction system supported by cofactor recycling with the NADP +-dependent formate dehydrogenase from Pseudomonas sp 101. Using this experimental set-up cyclohexane, octane and myristic acid were hydroxylated. To reduce the process costs a novel NADH-dependent mutant of CYP102A1 was designed. For recycling of NADH an NAD+-dependent FDH was used. The stability of the monooxygenase mutants under the reaction conditions in the biphasic system was quite high as revealed by total turnover numbers of up to 12,850 in the NADPH-dependent cyclohexane hydroxylation and up to 30,000 in the NADH-dependent myristic acid oxidation.
Different crystal form titania supported ruthenium nanoparticles for liquid phase hydrodeoxygenation of guaiacol
Long, Wei,Lv, Yang,Liu, Pingle,Hao, Fang,Xiong, Wei,Li, Xie,Cui, Haishuai,Luo, He'an
, p. 8426 - 8436 (2018)
Titania supported Ruthenium-based catalysts were prepared for liquid phase hydrodeoxygenation of guaiacol to cyclohexanol. The catalytic performance is affected by the different crystal forms of titania supports. Anatase and rutile titania supported catalyst 5%Ru/a-r-TiO2 presents higher BET surface area, better dispersion of Ru particles with smaller particle size of 3-4 nm, more acidic centers, and more Ruδ+ located at the boundary between anatase titania and rutile titania. Hence, 5%Ru/a-r-TiO2 gives the best catalytic performance of 95.33% conversion of guaiacol and 79.23% selectivity to cyclohexanol, other products mainly include cyclohexane, benzene, cyclohexanone and 1,2-cyclohexanediol. Based on the results of this work, the possible reaction path for guaiacol hydrodeoxygenation was proposed.
Demethoxylation of hydrogenated derivatives of guaiacol without external hydrogen over platinum catalyst
Miyagawa, Akari,Nakagawa, Yoshinao,Tamura, Masazumi,Tomishige, Keiichi
, p. 60 - 70 (2019)
Selective deoxygenation of 2-methoxycyclohexanone, one of the hydrogenated by-products in guaiacol hydrodeoxygenation, to phenol, cyclohexanone and cyclohexanol was investigated over carbon supported noble metal catalysts without external H2. Pt/C exhibited the best performance and the yield of target products reached 48% in water solvent at 493 K. This system can be applied to demethoxylation of 2-methoxycyclohexanol (49% yield). Demethoxylation of guaiacol is also possible under 0.1 MPa of H2 (46% yield). The yield of the target demethoxylation products was strongly dependent on the catalyst amount; too much catalyst decreased the yield due to the over-reaction, while the reaction stopped before total conversion of intermediates when the catalyst amount was too small. Fresh Pt/C catalyst has activity in hydrodeoxygenation of the target products and the reusability test showed deactivation of Pt/C during reaction, suggesting that deactivation at appropriate reaction progress controlled by catalyst amount is a key to good yield of the target products. In contrast to other noble metal catalysts, Pt/C has activity in both dehydrogenation of cyclohexane ring and hydrogenolysis of C–O bond, both of which contributed to the conversion of 2-methoxycyclohexanone to target demethoxylation products, according to the reactions of cyclohexanone and cyclohexanol as model substrates.
ACID-CATALYZED DECOMPOSITIONS OF HYDROPEROXIDES IN THE PRESENCE OF KETONES
Petrov, L. V.,Drozdova, T. I.,Lyuta, L. Ya.,Solyanikov, V. M.
, p. 226 - 232 (1990)
Ketones and aldehydes accelerate decomposition of hydroperoxides in acetonitrile solution in the presence of strong acids.An explanation of the effect, due to the formation of semiperketals (semiperacetals) which undergo rapid acid-catalytic decomposition, is proposed.The macrostage character of the reaction of acid-catalyzed decomposition of cyclohexyl hydroperoxide was demonstrated for the first time.The initially slow decomposition takes place homolytically and yields the product cyclohexanone, which accelerates decomposition.
Mechanistic study of decomposition of cyclohexyl hydroperoxide catalysed by manganese(III) tetraarylporphyrins
Hansen, Carola B.,Mul, Guido,Tabor, Roland B. J.,Drenth, Wiendelt
, p. 497 - 502 (1993)
The reaction between manganese(III) tetraarylporhyrins and cyclohexyl hydroperoxide has been investigated.Since pyridine increases the decomposition rate of cyclohexyl hydroperoxide, all experiments were performed in the presence of pyridine.Experiments with 2,6-di-tert-butylpyridine showed that pyridine increases the reaction rate by ligation to the manganese porphyrin as well as by acting as a base.Cyclohexyl hydroperoxide is decomposed into cyclohexanol and cyclohexanone.Since neither 3,3,5,5-tetramethylcyclohexanol nor cyclohexanol-d12 are oxidized under these reaction conditions, cyclohexanone is formed directly from the peroxide and not by oxidation of the alcohol.During the reaction, a manganese(V)oxo porphyrin complex is formed.This complex may react with (i) the peroxide under formation of cyclohexanol and molecular oxygen, (ii) the solvent cyclohexane, or (iii) manganese(III) porphyrin.The latter reaction leads to destruction of the catalyst.This destruction is prevented by introduction of bulky groups on the ortho positions of the phenyl.The scission of the hydroperoxide is suggested to be heterolytic.It is also base-catalysed.The rate-determining step in the decomposition of cyclohexyl hydroperoxide is scission of the oxygen-oxygen bond of the manganese peroxyl porphyrin complex.A mechanism in line with the kinetic data is proposed.
INFLUENCE OF CYCLODEXTRINS ON THE SODIUM BOROHYDRIDE REDUCTION OF CYCLOHEXENONES
Chenevert, Robert,Chamberland, Daniel
, p. 1117 - 1118 (1985)
The sodium borohydride reduction of cyclohexenones in aqueous medium is changed in the presence of cyclodextrins. β-cyclodextrin favours the 1,4-reduction over the 1,2-reduction whereas α-cyclodextrin favours the 1,2-reduction.
Efficient and selective oxidation of hydrocarbons with tert-butyl hydroperoxide catalyzed by oxidovanadium(IV) unsymmetrical Schiff base complex supported on γ-Fe2O3 magnetic nanoparticles
Ardakani, Mehdi Hatefi,Sabet, Mohammad,Samani, Mahnaz
, (2022/01/22)
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
Rational synthesis of palladium nanoparticles modified by phosphorous for the conversion of diphenyl ether to KA oil
Bai, Hong-Cun,Cao, Jing-Pei,Jiang, Wei,Wei, Yu-Lei,Xie, Jin-Xuan,Zhang, Chuang,Zhao, Liang,Zhao, Ming,Zhao, Xiao-Yan
, (2021/12/23)
Conversion of lignin-derived molecules into value-added chemicals is critical for sustainable chemistry but still challenging. Herein, phosphorus-modified palladium catalyzed the degradation of lignin-derived 4-O-5 linkage to produce KA oil (cyclohexanone-cyclohexanol oil) was reported. The reaction proceeds via a restricted partial hydrogenation-hydrolysis pathway. Phosphorus-modified palladium catalyst suppressed the full hydrogenation of diary ether, which was the key point to produce KA oil selectively. Under the optimized conditions, the 4.5 nm Pd-P NPs could catalyze the conversion of 4-O-5 linkage into KA oil in 83% selectivity with a high production rate of 32.5 mmol·g?1Pd·min?1. This study represented an original method for KA oil production.
Selective hydrogenation of substituted styrene to alkylbenzene catalyzed by Al2O3 nanoparticles
Kaleeswari, Kalairajan,Tamil Selvi, Arunachalam
, (2022/01/22)
A straightforward and suitable protocol is described for the conversion of substituted styrene to alkylbenzenes in the presence of Al2O3 nanoparticles (nano-Al2O3) as heterogeneous solid catalysts using N2H4·H2O as a hydrogen source under mild reaction conditions. A complete conversion of styrene is obtained using nano-Al2O3 as a heterogeneous catalyst. Besides, this catalyst system is also successfully applied to promote the broad range of styrene substituted derivatives to their respective alkylbenzene compounds in moderate to higher conversions. The reaction is discovered to be heterogeneous in nature and nano-Al2O3 can be reused for three runs with no diminish in its performance. Besides, the analyses of the fresh and three times reused nano-Al2O3 solid by various analytical techniques. Transmission electron microscope indicates that the structural features, surface morphology, and particle size endure unchanged throughout the reaction. Some of the significant features of this procedure are mild reaction conditions, price effectiveness of the catalyst (Pd or Pt free catalyst), high conversion, functional group endurance, absence of noble metals/additives, and reusability of the catalyst. The scope of the reaction procedure can be extended to various linear and cyclic alkenes. Graphical abstract: [Figure not available: see fulltext.]
