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All total 219 Articles be foundMesoporous silica gel as an effective and eco-friendly catalyst for highly selective preparation of cyclohexanone oxime by vapor phase oxidation of cyclohexylamine with air
Liu, Shuilin,You, Kuiyi,Jian, Jian,Zhao, Fangfang,Zhong, Wenzhou,Yin, Dulin,Liu, Pingle,Ai, Qiuhong,Luo, He'an
, p. 239 - 249 (2016)
A simple and environmentally benign approach to highly selective preparation of cyclohexanone oxime by vapor phase catalytic oxidation of cyclohexylamine with air over mesoporous silica gel under atmospheric pressure has been successfully developed in this work. The results demonstrate that the nonmetallic mesoporous silica gel is an effective and eco-friendly catalyst for the vapor phase selective oxidation of cyclohexylamine to cyclohexanone oxime and the surface silicon hydroxyl groups as active sites are responsible for the excellent catalytic performance of silica gel. The present silica gel catalyst has advantages of low cost, long-time stable reactivity, easy regeneration, and reusability. This method employing inexpensive mesoporous silica gel as catalyst and air as green terminal oxidant under facile conditions is a promising process and has the potential to enable sustainable production of cyclohexanone oxime from the selective oxidation of cyclohexylamine with air in industrial applications.
Preparation of cyclic ketoximes using aqueous hydroxylamine in ionic liquids
Ren, Rex X,Ou, Wei
, p. 8445 - 8446 (2001)
Cyclohexanone oxime (the precursor for making ε-caprolactam) is readily prepared from cyclohexanone using aqueous hydroxylamine in ionic liquids.
A novel hydroxylamine ionic liquid salt resulting from the stabilization of NH2OH by a SO3H-functionalized ionic liquid
Li, Zhihui,Yang, Qiusheng,Qi, Xudong,Xu, Yuanyuan,Zhang, Dongsheng,Wang, Yanji,Zhao, Xinqiang
, p. 1930 - 1932 (2015)
A SO3H-functionalized ionic liquid was used as an alternative to conventional inorganic acids in hydroxylamine stabilization, leading to the formation of a novel hydroxylamine ionic liquid salt that exhibits improved thermal stability and reactivity in the one-step, solvent-free synthesis of caprolactam in comparison with hydroxylamine hydrochloride and hydroxylamine sulfate.
A clean conversion of carbonyl compounds to oximes using silica gel supported hydroxylamine hydrochloride
Kiasat, Ali Reza,Kazemi, Foad,Nourbakhsh, Kazem
, p. 1193 - 1196 (2004)
The efficient condensation of carbonyl compounds with hydroxylamine hydrochloride under solvent free conditions is described.
Mercury-catalyzed rearrangement of ketoximes into amides and lactams in acetonitrile
Ramalingan, Chennan,Park, Yong-Tae
, p. 4536 - 4538 (2007)
(Chemical Equation Presented) An acetonitrile solution of mercury(II) chloride has been found to catalyze efficiently the conversion of a diverse range of ketoximes into their corresponding amides/lactams.
Pd/C Catalyzed selective hydrogenation of nitrobenzene to cyclohexanone oxime in the presence of NH2OH·HCl: Influence of the operative variables and insights on the reaction mechanism
Pietrobon, L.,Pontello, R.,Ronchin, L.,Sadraoui, C.,Tosetto, C.,Vavasori, A.
, (2020)
We studied the influence of temperature, solvent, pressure, catalysts type on the selectivity of nitrobenzene hydrogenation to cyclohexanone oxime (COX) in the presence of NH2OH. The best reaction conditions are: pressure 0.8 MPa, temperature 333 K, solvent ethers, and catalyst Pd/C5%. Other hydrogenation metal catalysts did not give comparable results. The amount of Pd/C influences the yield in COX, which rises above to 90 % at the highest load. The reaction profile shows that aniline is the reaction intermediate. Indeed, aniline as a substrate gives COX, though in lower yield than that achieved employing nitrobenzene. The NH2OH parallel hydrogenation to NH4Cl, influences positively the selectivity to COX. It has been observed that COX, cyclohexanone and N-cyclohexylideneaniline are in equilibrium in the reaction solution and all likely derive from nucleophilic substitutions to a common imine intermediate formed on the Pd surface, whose high activity does not need any further metal catalyst.
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Naylor,Anderson
, p. 115 (1953)
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Donaruma,Huber
, p. 965 (1956)
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Annulation of Oxime-Ether Tethered Donor–Acceptor Cyclopropanes
Irwin, Lauren C.,Allen, Meredith A.,Vriesen, Matthew R.,Kerr, Michael A.
, p. 171 - 175 (2020)
Novel oxime-ether tethered cyclopropanes, when exposed to Yb(OTf)3 and heat, annulate to generate hydropyrrolo-oxazines products that can be taken to their respective pyrrolidines via hydrogenative N?O bond cleavage. The hydropyrrolo-oxazines are generated in a diastereoselective manner isolating the cis or trans product based on the temperature of the reaction. 20 examples of selective cis and trans hydropyrrolo-oxazines were generated in high yields by temperature control.
Enolate-Based Regioselective Anti-Beckmann C-C Bond Cleavage of Ketones
Jahn, Ullrich,Ma?ek, Tomá?
, p. 11608 - 11632 (2021)
The Baeyer-Villiger or Beckmann rearrangements are established methods for the cleavage of ketone derivatives under acidic conditions, proceeding for unsymmetrical precursors selectively at the more substituted site. However, the fragmentation regioselectivity cannot be switched and fragmentation at the less-substituted terminus is so far not possible. We report here that the reaction of ketone enolates with commercial alkyl nitrites provides a direct and regioselective way of fragmenting ketones into esters and oximes or ω-hydroxyimino esters, respectively. A comprehensive study of the scope of this reaction with respect to ketone classes and alkyl nitrites is presented. Control over the site of cleavage is gained through regioselective enolate formation by various bases. Oxidation of kinetic enolates of unsymmetrical ketones leads to the otherwise unavailable "anti-Beckmann"cleavage at the less-substituted side chain, while cleavage of thermodynamic enolates of the same ketones represents an alternative to the Baeyer-Villiger oxidation or the Beckmann rearrangement under basic conditions. The method is suited for the transformation of natural products and enables access to orthogonally reactive dicarbonyl compounds.
Metal-Free Synthesis of Adipic Acid via Organocatalytic Direct Oxidation of Cyclohexane under Ambient Temperature and Pressure
Matsumoto, Yohei,Kuriyama, Masami,Yamamoto, Kosuke,Nishida, Koyo,Onomura, Osamu
, p. 1312 - 1317 (2018)
A direct metal-free approach for the production of adipic acid from cyclohexane is reported. The use of N-hydroxyphthalimide (NHPI) as a catalyst in the presence of HNO3/TFA enables the direct oxidation of cyclohexane to yield adipic acid under ambient temperature and pressure via a simple procedure. This reaction proceeds through an initial oxidation of cyclohexane to cyclohexanone oxime and cyclohexanone followed by a second oxidation of these intermediates to adipic acid. NHPI plays a crucial role in both oxidation steps to achieve a high yield and selectivity for adipic acid.
One-pot conversion of cyclohexanol to ?-caprolactam using a multifunctional Na2WO4-acidic ionic liquid catalytic system
Wang, Hefang,Jia, Liyuan,Hu, Rongbin,Gao, Meidan,Wang, Yanji
, p. 58 - 64 (2017)
Na2WO4-acidic ionic liquid was used as a simple, ecofriendly, recyclable and efficient catalytic system for the one-pot conversion of cyclohexanol to ?-caprolactam. The effect of the structure of the ionic liquid on the catalytic activity of this system was investigated, and the results revealed that sulfonic acid-functionalized ionic liquids with HSO4?as an anion gave the best results. The highly efficient performance of this catalyst system was attributed to the phase-transfer behavior of the cation of the ionic liquid, the improved coordination of the substrate to bisperoxotungstate during the oxidation reaction, and the stabilization of the intermediate formed during the Beckmann rearrangement.
The influences of preparation methods on the structure and catalytic performance of single-wall carbon nanotubes supported palladium catalysts in nitrocyclohexane hydrogenation
Liu, Sihua,Hao, Fang,Liu, Pingle,Luo, He'An
, p. 22863 - 22868 (2015)
Single-wall carbon nanotubes (CNTs) supported palladium catalysts were prepared by different methods. The influences of different preparation methods on the structure and catalytic performance in nitrocyclohexane hydrogenation were investigated. The catalysts were characterized by nitrogen adsorption-desorption, XRD, TEM, hydrogen chemisorption and X-ray photoelectron spectroscopy. The results show that Pd/SWCNTs prepared by a water impregnation method provide a smaller particle size of palladium. The reduction conditions have great influence on the valence state of palladium on the support. A catalyst with smaller particle size, better dispersion and higher content of monovalent palladium exhibits better catalytic performance in nitrocyclohexane hydrogenation to cyclohexanone oxime. Pd/SWCNTs-2 prepared by a water impregnation method and reduced at 723 K has 96.4% selectivity when synthesizing cyclohexanone oxime with a 96.0% conversion from nitrocyclohexane under mild conditions of 0.3 MPa and 323 K.
Palladium supported catalysts for nitrocyclohexane hydrogenation to cyclohexanone oxime with high selectivity
Liu, Ping-Le,Zhang, Hai-Ke,Liu, Si-Hua,Yao, Zheng-Jie,Hao, Fang,Liao, Hong-Guang,You, Kui-Yi,Luo, He-An
, p. 2932 - 2938 (2013)
Different kinds of activated carbon- and carbon nanotube-supported palladium catalysts were investigated in the selective hydrogenation of nitrocyclohexane to cyclohexanone oxime under mild conditions. Carbon nanotube-supported palladium catalysts demonstrate better catalytic performance than activated carbon-supported palladium catalysts in general because of their mesoporous structures, which are favorable supports for the accessibility of the reactants to the active sites and the product desorption from the catalyst. Hydrogen chemisorption, transmission electron microscopy and X-ray photoelectron spectroscopy indicate that higher composition of Pd+ on the catalyst surface, larger palladium surface area, and better palladium dispersion contribute to an increase in the activity and selectivity toward cyclohexanone oxime. In addition, single-wall carbon nanotube-supported palladium catalysts give the best result of 97.7% conversion of nitrocyclohexane and 97.4% selectivity toward cyclohexanone oxime. On the basis of the results of GC-MS and the designed experiments, a possible reaction scheme was proposed. Brilliance in the performance: Carbon nanotube-supported palladium catalysts demonstrate better catalytic performance than activated carbon-supported palladium catalysts in general because of their mesoporous structures, which are favorable supports for the accessibility of the reactants to the active sites and the product desorption from the catalyst.
Kulevsky et al.
, p. 1154 (1973)
Hydrogenation of nitrocyclohexane to cyclohexanone oxime over Pd/CNT catalyst under mild conditions
Liao, Hong-Guang,Xiao, Yan-Juan,Zhang, Hai-Ke,Liu, Ping-Le,You, Kui-Yi,Wei, Chao,Luo, He'An
, p. 80 - 84 (2012)
The Pd/C, Pt/C, Ni/CNT and Pd/CNT catalysts were prepared by impregnation method and characterized by BET, XRD, TEM and H2 chemisorption. These catalysts were tested in the hydrogenation of nitrocyclohexane to cyclohexanone oxime. The results show that 5% Pd/CNT catalyst exhibits good performance, it gives nitrocyclohexane conversion of 97.6% and cyclohexanone oxime selectivity of 85.9% under mild conditions of 0.2 MPa and 323 K. The products include cyclohexanone oxime, cyclohexylamine, cyclohexanol and N- cyclohexylhydroxylamine. It has been found that higher temperature is in favor of the formation of cyclohexylamine, while the amount of cyclohexanol decreases with the increment of reaction temperature.
Oxidation of amines over alumina based catalysts
Rakottyay, Karol,Kaszonyi, Alexander,Vají?ek, Stanislav
, p. 33 - 41 (2010)
Amines were oxidized by molecular oxygen in the vapor phase at atmospheric pressure over alumina and silicotungstic acid/alumina catalysts. The study is focused on the influence of structure of amine and catalyst properties on the composition of the main reaction products and byproducts. Coating of γ-Al2O3 with silicotungstic acid or its semisalt can significantly enhance its catalytic activity in amine oxidation. The adsorption of amine on weak acidic sites of catalyst is essential for its oxidation to main reaction products. Cycloalkylamines are oxidized mainly to cyclic oximes (selectivity up to 64%) and Schiff bases of appropriate cycloalkanone and cycloalkylamine (selectivity up to 38%). Mainly nitriles (selectivity up to 55%) and appropriate Schiff bases (selectivity up to 54%) were observed in the oxidation products of primary alkylamines. Their molar ratio depends on the catalyst acidity and reaction conditions. 1,6-Hexanediamine is oxidized mainly to caprolactam (yield 48%) and other cyclic lactames and Schiff bases as well as to dinitrile (yield 13%).
Reduction of conjugated nitroalkenes with zinc borohydride. A mild method for converting monosubstituted nitroalkenes to nitroalkanes and disubstituted ones to oximes
Ranu,Chakraborty
, p. 5317 - 5322 (1992)
Mono-β-substituted conjugated nitroalkenes are readily reduced by zinc borohydride in 1,2-dimethoxyethane to the corresponding nitroalkanes, whereas the disubstituted ones furnish the corresponding oximes in excellent yields.
A convenient one-pot method of converting alcohols into oximes
Kiasat, Ali Reza,Kazemi, Foad,Nourbakhsh, Kazem
, p. 1809 - 1812 (2004)
The one-pot conversion of primary and secondary alcohols into oximes is reported using chromium trioxide supported on alumina and hydroxylamine hydrochloride under solvent free condition. This oxidation-oxime formation reaction has been applied to a range of aliphatic and benzylic alcohols.
Preparation of cyclic prodiginines by mutasynthesis in pseudomonas putida kt2440
Klein, Andreas Sebastian,Brass, Hannah Ursula Clara,Klebl, David Paul,Classen, Thomas,Loeschcke, Anita,Drepper, Thomas,Sievers, Sonja,Jaeger, Karl-Erich,Pietruszka, J?rg
, p. 1545 - 1552 (2018)
Prodiginines are a group of naturally occurring pyrrole alkaloids produced by various microorganisms and known for their broad biological activities. The production of nature-inspired cyclic prodiginines was enabled by combining organic synthesis with a mutasynthesis approach based on the GRAS (generally recognized as safe) certified host strain Pseudomonas putida KT2440. The newly prepared prodiginines exerted antimicrobial effects against relevant alternative biotechnological microbial hosts whereas P. putida itself exhibited remarkable tolerance against all tested prodiginines, thus corroborating the bacterium’s exceptional suitability as a mutasynthesis host for the production of these cytotoxic secondary metabolites. Moreover, the produced cyclic prodiginines proved to be autophagy modulators in human breast cancer cells. One promising cyclic prodiginine derivative stood out, being twice as potent as prodigiosin, the most prominent member of the prodiginine family, and its synthetic derivative obatoclax mesylate.
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Robertson
, p. 395,397 (1948)
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Site-specific catalytic activities to facilitate solvent-free aerobic oxidation of cyclohexylamine to cyclohexanone oxime over highly efficient Nb-modified SBA-15 catalysts
Ding, Wei,Mao, Liqiu,Peng, Haoyu,Yin, Dulin,Zhong, Wenzhou
, p. 3409 - 3422 (2020)
The development of highly active and selective heterogeneous catalysts for efficient oxidation of cyclohexylamine to cyclohexanone oxime is a challenge associated with the highly sensitive nitrogen center of cyclohexylamine. In this work, dispersed Nb oxide supported on SBA-15 catalysts are disclosed to efficiently catalyze the selective oxidation of cyclohexylamine with high conversion (>75%) and selectivity (>84%) to cyclohexanone oxime by O2without any addition of solvent (TOF = 469.8 h?1, based on the molar amount of Nb sites). The role of the active-site structure identity in dictating the site-specific catalytic activities is probed with the help of different reaction and control conditions and multiple spectroscopy methods. Complementary to the experimental results, further poisoning tests (with KSCN or dehydroxylation reagents) and DFT computational studies clearly unveil that the surface exposed active centers toward activation of the reactants are quite different: the surface -OH groups can catch the NH2group from cyclohexylamine by forming a hydrogen bond and lead to a more facile cyclohexylamine oxidation to desired products, while the monomeric or oligomeric Nb sites with a highly distorted structure play a key role in the dissociation of O2molecules beneficial for insertion of active oxygen species into cyclohexylamine. These catalysts exhibit not only satisfactory recyclability for cyclohexylamine oxidation but also efficiently catalyze the aerobic oxidation of a wide range of amines under solvent-free conditions.
Ammoximation: Direct Synthesis of Oximes from Ammonia, Oxygen, and Ketones
Armor, John N.
, p. 1453 - 1454 (1980)
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Reactivity of hydroxylamine ionic liquid salts in the direct synthesis of caprolactam from cyclohexanone under mild conditions
Li, Zhihui,Yang, Qiusheng,Gao, Liya,Xu, Yuanyuan,Zhang, Dongsheng,Wang, Shufang,Zhao, Xinqiang,Wang, Yanji
, p. 83619 - 83625 (2016)
The reactivity of several sulfobutyl hydrosulfate hydroxylamine ionic liquid salts in the direct synthesis of caprolactam from cyclohexanone under mild conditions was investigated. The results showed that the cyclohexanone conversion was mainly affected by cation species in the molecules of the hydroxylamine ionic liquid salts, and hydroxylamine N,N,N-trimethyl-N-sulfobutyl hydrosulfate salt was a better choice for the direct synthesis of caprolactam. The optimum reaction condition was at 80 °C for 4 h, and the suitable molar ratio of cyclohexanone: hydroxylamine ionic liquid salt: ZnCl2 was 2: 1:3. Under the optimal reaction conditions, cyclohexanone was almost completely converted into caprolactam, corresponding to 99.1% cyclohexanone conversion and 92.0% caprolactam selectivity. Furthermore, the reaction medium acetonitrile, and the ionic liquid which was combined in the hydroxylamine salt, can be recovered after the reaction, achieving an eco-friendly route for the direct synthesis of caprolactam.
Synthesis, Characterization, and Catalytic Activities of Palladium Complexes with Phenylene-Bridged Bis(thione) Ligands
Jia, Wei-Guo,Gao, Li-Li,Wang, Zhi-Bao,Sun, Li-Ying,Han, Ying-Feng
, p. 1946 - 1954 (2019)
The neutral phenylene-bridged bis(thione) compounds, 1,3-bis(3′-ethylimidazolyl-2′-thione)benzene (Betb), 1,3-bis(3′-butylimidazolyl-2′-thione)benzene (Bbtb), and 1,3-bis(3′-allylimidazolyl-2′-thione)benzene (Batb), have been synthesized and characterized. Reactions of palladium precursor PdCl2(CH3CN)2 with phenylene-bridged bis(thione) ligands in 1:2 ratio resulted in the formation of the complexes: PdCl2(L)2 (L = Betb, 3a; L = Bbtb, 3b; L = Batb, 3c, respectively). In contrast, treatment of the ligands with PdCl2(CH3CN)2 in 1:1 ratio gave cyclometalation palladium complexes Pd2+Cl(L-) (L = Betb-H, 4a; L = Bbtb-H, 4b; L = Batb-H, 4c) through the metal-induced C-H activation. Complexes 4a-c can also be obtained by the reaction of bis(thione) ligands and PdCl2 in 1:1 ratio. The reaction of 3a-c with additional PdCl2(CH3CN)2 also afforded complexes 4a-c. All ligands and palladium complexes were fully characterized by one-/two-dimensional NMR spectra, mass spectrometry, and infrared spectrometry. And the molecular structures of 3a-c, 4a, and 4c have been determined by the single-crystal X-ray diffraction method. Furthermore, the detailed spectroscopic properties and catalytic activities of the complexes for the reduction of nitro compounds were discussed in terms of the modification of the coordination ligands to the center metal.
Method for co-producing adipic acid and cyclohexanone-oxime from cyclohexane
-
, (2021/06/13)
The invention relates to a method for co-producing adipic acid and cyclohexanone-oxime from cyclohexane. The method comprises the following steps: (1) carrying out oxidation nitration on cyclohexane and NOx to generate adipic acid, nitrocyclohexane, nitrogen oxides and a byproduct-A, and separating to obtain crude adipic acid and nitrocyclohexane; (2) carrying out catalytic hydrogenation on the obtained nitrocyclohexane and hydrogen to generate cyclohexanone-oxime and a small amount of cyclohexylamine, separating to obtain crude cyclohexanone-oxime and cyclohexylamine, and enabling cyclohexylamine to be directly used as a byproduct or to be continuously converted into cyclohexanone-oxime. and (3) partially oxidizing the cyclohexylamine obtained in the previous step with molecular oxygen to obtain an oxidation reaction product consisting of cyclohexanone-oxime, a byproduct B and possibly unconverted cyclohexylamine, and then separating the oxidation reaction product without separation, or firstly separating part or all of water in the oxidation reaction product, carrying out hydrogenation amination reaction under the action of a catalyst, or carrying out hydrogenation and amination reaction, or only carrying out hydrogenation reaction, and then separating to obtain the cyclohexanone-oxime. The method can realize high-selectivity co-production of adipic acid and cyclohexanone-oxime, and is short in process flow, low in equipment investment and low in material consumption, energy consumption and cost.
Poly(N-vinylimidazole): A biocompatible and biodegradable functional polymer, metal-free, and highly recyclable heterogeneous catalyst for the mechanochemical synthesis of oximes
Fahim, Hoda,Ghaffari Khaligh, Nader,Gorjian, Hayedeh
, p. 2007 - 2012 (2022/01/08)
The catalytic activity of poly(N-vinylimidazole), a biocompatible and biodegradable synthetic functional polymer, was investigated for the synthesis of oximes as an efficient, halogen-free, and reusable heterogeneous catalyst. The corresponding oximes were afforded in high to excellent yields at room temperature and in short times using the planetary ball mill technique. Some merits, such as the short reaction times and good yields for poorly active carbonyl compounds, and avoiding toxic, expensive, metal-containing catalysts, and hazardous and flammable solvents, can be mentioned for the current catalytic synthesis of the oximes. Furthermore, the heterogeneous organocatalyst could be easily separated after the reaction, and the regenerated catalyst was reused several times with no significant loss of its catalytic activity.
