- A Direct Correlation between Dispersion, Metal Area, and Vapour Phase Hydrogenation of Aniline; a First Report
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Aniline hydrogenation activity is correlated with dispersion, crystallite size, and metal area over Rh/Al2O3 catalyst.
- Vishwanathan, Venkataraman,Narayanan, Sankarasubbier
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- Pd/TiO2-Photocatalyzed Self-Condensation of Primary Amines to Afford Secondary Amines at Ambient Temperature
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Symmetric secondary amines were synthesized by the self-condensation of primary amines over a palladium-loaded titanium dioxide (Pd/TiO2) photocatalyst. The reactions afforded a series of secondary amines in moderate to excellent isolated yields at ambient temperature (30 °C, in cyclopentyl methyl ether). Applicability for one-pot pharmaceutical synthesis was demonstrated by a photocatalytic reaction sequence of self-condensation of an amine followed by N-alkylation of the resulting secondary amine with an alcohol.
- Wang, Lyu-Ming,Kobayashi, Kensuke,Arisawa, Mitsuhiro,Saito, Susumu,Naka, Hiroshi
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- Selective reduction of halo-nitro aromatic compounds using [Rh]/DHTANa as catalyst in an aqueous bi-phase system
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The use of water as co-solvent for biphasic reactions and of easily recyclable water-soluble catalysts are highly desirable for the realization of greener processes. The selective reduction of halo nitroarenes to the corresponding haloanilines is a very important industrial transformation for the production of agrochemicals, pigments, bactericides and pharmaceuticals and is not easy to obtain. The application of a water soluble catalyst, prepared by rhodium species and a cheap thioligand, in the hydrogenation of some halonitroarenes is here described. Excellent conversions, good recyclability of the catalytic species embedded in the aqueous phase and very high selectivity are demonstrated.
- Rathod, Vikas Damu,Paganelli, Stefano,Piccolo, Oreste
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- Vapor-Phase Amination of Cyclohexanol over Silica-Supported Platinum Group Metal Catalysts
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Vapor-phase amination of cyclohexanol with ammonia over silica-supported platinum and other platinum group metal (Ru, Rh, Pd, Ir) catalysts has been studied.Cyclohexylamine and aniline are the main products.Platinum is the most active metal, although ther
- Hamada, Hideaki,Kuwahara, Yasushi,Sato, Takahiro,Wakabayashi, Katsuhiko
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- Comparison of hydrogen adsorption and aniline hydrogenation over co-precipitated Co/Al2O3 and Ni/Al2O3 catalysts
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Co/Al2O3 catalysts with different cobalt content (10-50 wt.%) have been prepared by a co-precipitation method at pH 8. The catalysts were characterised by physical measurements (pore volume, bulk density, surface area and XRD) and by
- Narayanan, Sankarasubbier,Unnikrishnan, Ramachandran Pillai
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- An efficient heterogenized palladium catalyst for N-alkylation of amines and α-alkylation of ketones using alcohols
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A silica supported palladium-NiXantphos complex is reported as an efficient and a high turnover heterogeneous catalyst for the N-alkylation of amines and the α-alkylation of ketones using readily available alcohols under neat conditions at 120-140 °C following hydrogen borrowing strategy. The catalyst is easily separable and offers negligible amount of palladium leaching (0.01 ppm). A high turnover number of about 46000 for the N-alkylation of amines and 4400 for the α-alkylation of ketones were achieved in the respective single batch reactions. The catalyst is recyclable up to four times without appreciable change in catalytic performance.
- Dang, Tuan Thanh,Shan, Siah Pei,Ramalingam, Balamurugan,Seayad, Abdul Majeed
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- Concurrent Hydrogenation of Aromatic and Nitro Groups over Carbon-Supported Ruthenium Catalysts
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The concurrent hydrogenation of aromatic and nitro groups poses particular challenges due to the highly differing adsorption strengths of the two chemical moieties on the surfaces of metal catalysts. In a study of the hydrogenation of nitrobenzene as a model reaction, catalysts of ruthenium supported on carbon nanotubes (Ru/CNT) provided an ideal compromise, allowing for hydrogenation of both the aromatic ring and the nitro group. The use of methyl-labeled substrates enabled tracking the pathway of specific substrates and obtaining insight into the relative rates for the hydrogenation of nitrobenzene and intermediates. Together with findings on the coadsorption of nitrobenzene and aniline on the Ru/CNT catalyst, an advanced mechanistic model for the hydrogenation of nitrobenzene emerges. (Chemical Equation Presented).
- Tomkins, Patrick,Gebauer-Henke, Ewa,Leitner, Walter,Müller, Thomas E.
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- Ni-Catalyzed reductive amination of phenols with ammonia or amines into cyclohexylamines
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Phenol and its derivatives, which naturally occur in lignocellulose, can be considered as a renewable feedstock not only for aromatic, but also for alicyclic compounds, such as primary and N-substituted cyclohexylamines. So far, the latter are mostly produced from non-renewable starting materials like benzene via problematic nitration/reduction or cross-coupling routes. Herein, an efficient reductive amination of phenol with ammonia or amines is demonstrated, for the first time without the need for rare and expensive noble metals and without using any additives. Various supported Ni catalysts were screened and we elucidated the influence of the key parameters, including the acid-base properties of the supporting material. Acquired knowledge was then applied to different phenol-ammonia/amine combinations, resulting in the synthesis of various primary, secondary and tertiary cyclohexylamines in fair to very high yields.
- Cuypers, Thomas,Morias, Thomas,Windels, Simon,Marquez, Carlos,Van Goethem, Cédric,Vankelecom, Ivo,De Vos, Dirk E.
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- Selective synthesis of octahydroacridines and diannelated pyridines over zinc-containing mesoporous aluminosilicate molecular sieve catalysts
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We demonstrate a very eco-friendly and single-step catalytic method for the highly selective synthesis of 1,2,3,4,5,6,7,8-octahydroacridine (OHA) by the vapour phase aminocyclization of cyclohexanone (CyO) with a mixture of formaldehyde (HCHO) and ammonia (NH3) over mesoporous bimetallic ZnAlMCM-41 (ZnAl-41) molecular sieves as efficient catalysts, which were synthesised by a simple basic hydrothermal method. To find optimum parameters for the synthesis of OHA, different reaction parameters, such as temperature, time on stream (TOS), weight hourly space velocity (WHSV), and feed molar ratios of CyO:HCHO:NH3, have been extensively studied. The used ZnAl-41 catalysts were treated by washing and calcination to recover the recyclable catalysts which were then reused in these reactions to study their catalytic abilities. To selectively synthesize a variety of pyridine compounds, the active mesoporous catalysts, namely, ZnAl-41(75) and recyclable ZnAl-41(75), with different reaction parameters, were extensively used in the vapour phase aminocyclization reaction with different aldehydes and cycloketones, and produced excellent product selectivities, e.g., 9-alkyl substituted octahydroacridines (9-ASOHAs) and diannelated pyridines (DAPs), with good ketone conversions. In this catalytic reaction, OHA, 9-ASOHAs and DAPs are the main products and are important as starting materials in the preparation of biologically active compounds, drugs, dyes and alkaloids. It is shown by our remarkable catalytic results that the ZnAl-41(75) catalyst, as an environmentally friendly heterogeneous catalyst, has outstanding catalytic activity in the production of OHA, 9-ASOHAs and DAPs by a single-step synthetic method.
- Selvaraj, Manickam,Assiri, Mohammed A.
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- RAPID AND EFFICIENT REDUCTION OF ALIPHATIC NITRO COMPOUNDS TO AMINES
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The combination of NaBH4 with catalytic quantities of NiCl2 smoothly reduces aliphatic nitro compounds to amines in methanol; Ni2B formed in situ is the active catalyst.
- Osby, John O.,Ganem, Bruce
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- New active-iron based reducing system for carbonyl compounds and imines. Stereoselective reduction of cyclic ketones
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The reaction of different carbonyl compounds and imines with a mixture of iron(II) chloride tetrahydrate, an excess of lithium powder, and a catalytic amount of 4,4′-di-tert-butylbiphenyl (DTBB, 5 mol%) in THF at room temperature, led to the formation of the corresponding alcohols and amines, respectively. The process was also applied to the transformation of α,β-unsaturated carbonyl compounds into the corresponding saturated alcohols. The new reducing system exhibited good to excellent diastereoselectivity toward the reduction of different monocyclic and polycyclic ketones.
- Moglie, Yanina,Alonso, Francisco,Vitale, Cristian,Yus, Miguel,Radivoy, Gabriel
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- An improved method for the complete hydrogenation of aromatic compounds under 1 bar H2 with platinum nanowires
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A little pressure for a lot of gain: An efficient method has been developed for the controlled hydrogenation of phenol using a platinum nanowire catalyst under mild conditions (>98.4%, 1atm H2, 60°C). The catalyst also exhibited high levels of activity and selectivity towards other selected aromatic compounds bearing a variety of different substituents, demonstrating its generality towards the hydrogenation of aromatic compounds.
- Yu, Tingting,Wang, Jiaqing,Li, Xinming,Cao, Xueqin,Gu, Hongwei
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- Cyclization of α,ω Aliphatic Diamines and Conversion of Primary Amines to Symmetrical Tertiary Amines by a Homogeneous Ruthenium Catalyst
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α,ω Aliphatic diamines were cyclized to heterocyclic amines by being heated at 180 deg C for 5 h with RuCl2(Ph3P)3 in diphenyl ether.Primary amines having an α-hydrogen atom are converted to symmetrical tertiary amines by being heated at 185 or 235 deg C for 8 h with RuCl3*3H2O and Ph3P in THF solution.
- Bui-The-Khai,Concilio, Carlo,Porzi, Gianni
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- Chemoselective deprotection of N-allylic amines using DDQ
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A highly chemoselective and simple method for the deprotection of N-allylic amines using DDQ has been developed. The use of DDQ in dichloromethane-water provides a mild and efficient one-step deallylation of a wide variety of orthogonally protected tertiary amine derivatives.
- Kumar, Pradeep,Cherian, Shijo K.,Jain, Ruchi,Show, Krishanu
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- SELECTIVE CONVERSION OF PRIMARY AMINES INRO N,N-DIMETHYLALKYL- OR N,N-DIALKYLMETHYL-AMINES WITH METHANOL AND RuCl2(Ph3P)3
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N,N-dimethylalkyl- or N,N-dialkylmethyl-amines are selectively obtained from the reaction between aliphatic amines and methanol at 180 deg C for 7 h in the presence of RuCl2(Ph3P)3 catalyst.
- Arcelli, Antonio,Khai, Bui-The,Porzi, Gianni
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- Hydrogenation of aniline to cyclohexylamine in supercritical carbon dioxide: Significance of phase behaviour
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Hydrogenation of aniline to cyclohexylamine was carried out in supercritical carbon dioxide using a variety of noble metal (Pt, Pd and Rh) catalysts. At 80 °C and 8 MPa of CO2 pressure, >95% of aniline conversion with 93% selectivity to cyclohexylamine was achieved on 5% Rh/Al2O3. A strong influence of phase behaviour related to the CO2 pressure was found on the conversion and selectivity. Optimization of reaction parameters resulted in a higher overall activity in the biphase (liquid substrate + gaseous H2 and CO2) than in the single phase (liquid substrate-CO2-H2) condition. It has been found that the interaction of CO2 with amine leads to the formation of solid carbamic acid, which enhanced the selectivity of cyclohexylamine, but reduced the conversion significantly. Furthermore, reaction temperature played a crucial role in preventing the formation of carbamic acid and also maintained a reasonably high reaction performance in terms of conversion and selectivity.
- Chatterjee,Sato,Kawanami,Ishizaka,Yokoyama,Suzuki
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- Selectivity Control on Hydrogenation of Substituted Nitroarenes through End-On Adsorption of Reactants in Zeolite-Encapsulated Platinum Nanoparticles
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Platinum nanoparticles encapsulated into zeolite Y (Pt@Y catalyst) exhibit excellent catalytic selectivity in the hydrogenation of substituted nitroarenes to form the corresponding aromatic amines, even after complete conversion. With the hydrogenation of p-chloronitrobenzene as a model, the role of zeolite encapsulation toward perfect selectivity can be attributed to constraint of the substrate adsorbed on the platinum surface in an end-on conformation. This conformation results in the activation of only one adsorbed group, with little influence on the other one in the molecule. Owing to a much lower apparent activation energy of Pt@Y for the hydrogenation of a separately adsorbed nitro group than that of the adsorbed chloro group, the Pt@Y catalyst can prevent hydrodechlorination of p-chloronitrobenzene under mild conditions. Moreover, such a conformation results in a reduced adsorption energy of target p-chloroaniline on the platinum surface; thus suppressing the reactivity of hydrodechlorination of p-chloroaniline to circumvent further C?Cl bond breakage.
- Chen, Qiang,Wang, Mengyue,Zhang, Chengxi,Ren, Kui,Xin, Yue,Zhao, Ming,Xing, Enhui
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- Formation of secondary or tertiary aliphatic amines in aqueous media
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Secondary and tertiary amines can be easily obtained from primary and secondary amines, respectively, in completely aqueous media, in the presence of a bicatalytic system formed of cheap commercial aluminum (Al) powder and 5% rhodium (Rh) or ruthenium (Ru) deposed on charcoal.
- Marieta Simion, Alina,Arimura, Takashi,Miyazawa, Akira,Simion, Cristian,Surya Prakash,Olah, George A.,Tashiro, Masashi
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- Iridium-catalyzed condensation of primary amines to form secondary amines
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Symmetric secondary amines are readily obtained by heating a neat primary amine with 0.5 mol% of bis(dichloro[h5-pentamethylcyclopentadienyl] iridium). The products are isolated by direct distillation in good yields. Georg Thieme Verlag Stuttgart - New York.
- Lorentz-Petersen, Linda L. R.,Jensen, Paw,Madsen, Robert
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- Transformylating amine with DMF to formamide over CeO2 catalyst
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We here report a new protocol for the formylation of various amines, primary or secondary, aromatic or alkyl, cyclic or linear, mono- or di-amine, with dimethylformamide (DMF) as the formylation reagent to obtain the corresponding formamides in good to excellent yields over CeO2 catalyst. The reaction requires no homogeneous acidic or basic additives and is tolerant to water.
- Wang, Yehong,Wang, Feng,Zhang, Chaofeng,Zhang, Jian,Li, Mingrun,Xu, Jie
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- Catalytic Leuckart-Wallach-type reductive amination of ketones
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A Cp*Rh(III) complex catalyzes reductive amination of ketones using HCOONH4 at 50-70°C to give the corresponding primary amines in high yields. The reaction is clean and operationally simple and proceeds at a lower temperature and with higher chemoselectivity than the original Leuckart-Wallach reaction. The new method has been applied to the synthesis of α-amino acids directly from α-keto acids.
- Kitamura, Masato,Lee, Donghyun,Hayashi, Shinnosuke,Tanaka, Shinji,Yoshimura, Masahiro
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- TRICHLOROSILANE-IMINE COMPLEXES. A NEW METHOD FOR THE REDUCTION OF IMINES TO AMINES
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It has been found that trichlorosilane adds regio-specifically to the carbon-nitrogen double bond of imines under mild conditions to yield hydrolytically unstable N-trichlorosilyl intermediates.The latter can be hydrolyzed in situ by alcoholic base to give the corresponding amines in moderate to good yields.Variously substituted aldo and keto imines, both alkyl and aryl, were tested to demonstrate the scope of the reaction.The facility of trichlorosilane addition appears to depend on the nature of the groups directly attached to the carbon-nitrogen double bond.Hydride trapping experiments suggest an intramolecular rather than intermolecular hydride transfer during the course of the reaction.
- Benkeser, Robert A.,Snyder, Dudley C.
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- One-Pot Selective Catalytic Synthesis of Pyrrolidone Derivatives from Ethyl Levulinate and Nitro Compounds
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N-substituted 5-methyl-2-pyrrolidones were prepared in a one-pot process starting from ethyl levulinate and nitro compounds in the presence of a nanosized Pt-based catalyst. Pt supported on TiO2nanotubes (Pt/TiO2-NT) catalyzed the synthesis of N-substituted 5-methyl-2-pyrrolidones through a cascade process involving the reduction of nitro compounds, formation of the intermediary imine, hydrogenation, and subsequent cyclization. A bifunctional metal–acid system was a suitable catalyst for the process. Pt supported on TiO2showed lower catalytic activity than Pt/TiO2-NT owing to the strong adsorption of nitro compounds during the first reaction step that poisoned the acidic sites and strongly decreased the rate of amination and cyclization. However, Pt/TiO2-NT with milder acid sites was less affected by the adsorption of nitro compounds and the full cascade process could proceed. The results indicate that the prepared Pt/TiO2-NT is a chemoselective and reusable catalyst that can be applied to the synthesis of a variety of N-substituted 5-methyl-2-pyrrolidones starting from nitro compounds with excellent yields in absence of an additional organic solvent under mild reaction conditions.
- Vidal, Juan D.,Climent, Maria J.,Corma, Avelino,Concepcion, Dr Patricia,Iborra, Sara
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- Molecular Assembly Line: Stepwise Hydrogenation of Multifunctional Substrates over Catalyst Mixtures
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The synthesis of many chemical products requires multiple steps. To simplify the overall synthesis by combining consecutive reaction steps, the concept of a molecular assembly line promises to yield high reaction rates and selectivities. In this study, mixtures of carbon nanotube (CNT)-supported catalysts were used to demonstrate the potential of this concept on hand of the hydrogenation of nitrobenzene via aniline to cyclohexylamine. Mixtures of Pt/CNT, having a high activity in nitrobenzene hydrogenation, and of Ru/CNT, highly selective for the hydrogenation of aniline to cyclohexylamine, provided high activity at constant high selectivity. Varying the Pt:Ru ratio to 5:95 was found to be the best case scenario, for which the rates of the two consecutive reaction steps are balanced. The use of catalyst mixtures rather than bimetallic catalysts avoids complex phenomena such as phase separation or migration of one of the metals to the surface of the bimetallic particles.
- Tomkins, Patrick,Gebauer-Henke, Ewa,Müller, Thomas E.
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- Synthesis, Characterization, and Catalytic Activity of Beidellite-Montmorillonite Layered Silicates and their Pillared Analogues
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A synthetic beidellite-smectite, characterized by a range of techniques, including high-resolution 27Al and 29Si solid-state n.m.r. spectroscopy, shows interesting catalytic activity (in secondary amine formation from cyclohexylamine, in ester production from hex-1-ene and acetic acid, and in ether synthesis from pentanol): the selectivities differ significantly from those of montmorillonite-smectites.
- Diddams, Paul A.,Thomas, John M.,Jones, William,Ballantine, James A.,Purnell, J. Howard
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- Borohydride exchange resin, a new reducing agent for reductive amination
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Borohydride Exchange Resin is a useful, convenient reducing agent for the reductive amination of aldehydes and ketones in alcoholic solvent.
- Yoon,Kim,Son,Choi
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- THE PLATINUM COMPLEX CATALYZED TRANSFORMATION OF PRIMARY AMINE TO SECONDARY AMINE
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Platinum complex combined with SnCl2*2H2O activates a primary amine and catalyzes the transformation to the secondary amine at 180 deg C.Dibutylamine was obtained from butylamine in 74percent yield.
- Tsuji, Yasushi,Shida, Jun,Takeuchi, Ryo,Watanabe, Yoshihisa
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- Self-coupling of benzylamines over a highly active and selective supported copper catalyst to produce N-substituted amines by the borrowing hydrogen method
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Amines were used as hydrogen donor for the borrowing hydrogen methodology with a heterogeneous catalyst. Supported copper catalysts catalyzed the self-condensation reaction of primary amines to secondary amines/imines with high efficiency. The recyclable, non-leaching catalyst is synthesized by a sol-gel method, which allows entrapping copper nanoparticles in an alumina matrix. The synthesized copper catalysts were found to be active in the self-coupling of primary amines to produce secondary amines. The hydrogen donor for the transfer hydrogenation appears to be the primary amine, and no additional hydrogen or hydrogen transfer reagent is required. To the best of our knowledge, this is the first report of a copper based catalyst for this type of reaction using the borrowing hydrogen scheme.
- Liu, Huihui,Chuah, Gaik-Khuan,Jaenicke, Stephan
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- A Mild Reduction of Azomethines with Zinc Borohydride. Synthetic Application to Tandem Alkylation-Reduction of Nitriles
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The reduction of Schiff bases; N-benzylidene- and N-(1-phenylethylidene)arylamines with zinc borohydride in diethyl ether gave the corresponding amines in excellent yield.N-benzylidene-benzyl- and cyclohexylamine, N-(1-phenylethylidene)- and N-(cyclohexylidene)cyclohexylamines, however, require additional treatment with 6 N HCl to liberate the amine-borane complex to give the corresponding amines in quantitative yield.The procedure was also applied in the tandem alkylation-reduction of nitriles to yield 1-phenylalkylamines in good yield.
- Kotsuki, Hiyoshizo,Yoshimura, Naka,Kadota, Isao,Ushio, Yasuyuki,Ochi, Masamitsu
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- The Co-amination of Phenol and Cyclohexanol with Palladium-on-carbon Catalyst in the Liquid Phase. An Application of a Hydrogen-transfer Reaction
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Phenol and Cyclohexanol are simultaneously aminated to aniline and cyclohexylamine by ammonolysis with the palladium-on-carbon catalyst in the liquid phase, although the amination of either phenol or cyclohexanol hardly occurs without the other.In contras
- Hamada, Hideaki,Yamamoto, Makoto,Kuwahara, Yasushi,Matsuzaki, Takehiko,Wakabayashi, Katsuhiro
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- Sodium anilinide-cyclohexylamide pair: Synthesis, characterization, and hydrogen storage properties
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The lack of efficient hydrogen storage material is one of the bottlenecks for the large-scale implementation of hydrogen energy. Here, a series of new hydrogen storage materials, i.e., anilinide-cyclohexylamide pairs, are proposed via the metallation of an aniline-cyclohexylamine pair. DFT calculations show that the enthalpy change of hydrogen desorption (ΔHd) can be significantly tuned from 60.0 kJ per mol-H2 for the pristine aniline-cyclohexylamine pair to 42.2 kJ per mol-H2 for sodium anilinide-cyclohexylamide and 38.7 kJ per mol-H2 for potassium anilinide-cyclohexylamide, where an interesting correlation between the electronegativity of the metal and the ΔHd was observed. Experimentally, the sodium anilinide-cyclohexylamide pair was successfully synthesised with a theoretical hydrogen capacity of 4.9 wt%, and the hydrogenation and dehydrogenation cycle can be achieved at a relatively low temperature of 150 °C in the presence of commercial catalysts, in clear contrast to the pristine aniline-cyclohexylamine pair which undergoes dehydrogenation at elevated temperatures.
- Jing, Zijun,Yu, Yang,Chen, Ruting,Tan, Khai Chen,He, Teng,Wu, Anan,Pei, Qijun,Chua, Yong Shen,Zheng, Dewen,Zhang, Xi,Ge, Zhixin,Zhang, Fudong,Chen, Ping
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- A FACILE SYNTHESIS OF SYMMETRICAL SECONDARY AMINES FROM PRIMARY AMINES PROMOTED BY THE HOMOGENEOUS CATALYST RuCl2(Ph3P)3
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Primary amines bearing an α-hydrogen atom are quantitatively converted to symmetrical secondary amines by heating at 185 deg C for 5 h in the presence of a catalytic amount of RuCl2(Ph3)3.
- Bui-The-Khai,Concilio, Carlo,Porzi, Gianni
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- Solid base catalyzed highly efficient N-alkylation of amines with alcohols in a solvent-free system
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Different from any other catalytic systems containing transition metals and additives, sodium hydroxide itself was found to be a unique and effective catalyst for the solvent-free synthesis of the secondary amines via the N-alkylation of amines with alcohols. For the reaction of aniline with benzyl alcohol, 99.6 mol% conversion of aniline and 99.5% selectivity of the product were achieved under optimal conditions. Also, high conversion and selectivity could be acquired for the N-alkylations of various amines with alcohols, implying the universality of this methodology. Mechanistic studies revealed that this novel reaction most possibly proceeds with a base-catalyzed mechanism.
- Lu,Sun,Wei,Peng,Zhou,Xia
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- Chemical Conversions using Sheet Silicates: Novel Intermolecular Elimination of Ammonia from Amines
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Ammonia is readily eliminated from molecular pairs of intercalated primary amines thereby generating the secondary amines in high yield in a novel proton-mediated reaction; certain cyclic secondary amines produce unusual products by a similar interlamellar reaction.
- Ballantine, James A.,Purnell, Howard,Rayanakorn, Mongkon,Thomas, John M.,Williams, Kevin J.
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- Insight into the Role of Additives in Catalytic Synthesis of Cyclohexylamine from Nitrobenzene
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Cyclohexylamine is a versatile intermediate in various chemical industries, which can be expediently synthesized via hydrogenation of aniline or nitrobenzene. However, such processes always suffer from side reactions. Many reports have found that specific additives can suppress the formation of side products, but the mechanism is still not clear. In this work, results suggest that it is the hydroxide ion of alkali metal hydroxides, rather than the cations, which plays a key role in suppressing the side reactions on supported Ru-based catalysts. With the assistance of LiOH, the selectivity toward cyclohexylamine increased from 85.4% to 100%. Side products, such as dicyclohexylamine, cyclohexanol and N-isopropyl cyclohexylamine, could no longer be detected. Theoretical calculations further disclosed that addition of alkali metal hydroxides inhibited the dissociation of enamine and decreased the adsorption energy of cyclohexylamine, which might be the reasons for a better selectivity. However, the addition of alkali metal hydroxides reduced the activity of nitrobenzene hydrogenation by unfolding the condensation reaction route. To recover or even further enhance the catalytic performance, a second metal component was introduced and the resultant RuNi/AC exhibited a significant improvement in activity compared with Ru/AC.
- Li, Xuefeng,Wang, Zhe,Mao, Shanjun,Chen, Yiqing,Tang, Minghui,Li, Haoran,Wang, Yong
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- Highly efficient heterogeneous gold-catalyzed direct synthesis of tertiary and secondary amines from alcohols and urea
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Urea, the white gold: The efficient synthesis of tertiary and secondary amines is achieved by heterogeneous gold-catalyzed direct amination of stoichiometric alcohols with urea in good to excellent yields. Via a hydrogen autotransfer pathway, the reactions of primary alcohols with urea give tertiary amines exclusively, while secondary alcohols selectively afford secondary amines.
- He, Lin,Qian, Yue,Ding, Ran-Sheng,Liu, Yong-Mei,He, He-Yong,Fan, Kang-Nian,Cao, Yong
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- Ceria supported Ru0-Ruδ+ clusters as efficient catalyst for arenes hydrogenation
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Selective hydrogenation of aromatic amines, especially chemicals such as aniline and bis(4-aminocyclohexyl)methane for non-yellowing polyurethane, is of particular interests due to the extensive applications. To conquer the existing difficulties in selective hydrogenation, the Ru0-Ruδ+/CeO2 catalyst with solid frustrated Lewis pairs was developed for aromatic amines hydrogenation with excellent activity and selectivity under relative milder conditions. The morphology, electronic and chemical properties, especially the Ru0-Ruδ+ clusters and reducible ceria were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electronic microscopy (SEM), X-ray photoelectron spectroscopy (XPS), CO2 temperature programmed desorption (CO2-TPD), H2 temperature programmed reduction (H2-TPR), H2 diffuse reflectance Fourier transform infrared spectroscopy (H2-DRIFT), Raman, etc. The 2% Ru/CeO2 catalyst exhibited good conversion of 95% and selectivity greater than 99% toward cyclohexylamine. The volcano curve describing the activity and Ru state was found. Owning to the “acidic site isolation” by surrounding alkaline sites, condensation between the neighboring amine molecules could be effectively suppressed. The catalyst also showed good stability and applicability for other aromatic amines and heteroarenes containing different functional groups.
- Cao, Yanwei,Zheng, Huan,Zhu, Gangli,Wu, Haihong,He, Lin
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supporting information
p. 770 - 774
(2020/08/24)
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- Aromatic compound hydrogenation and hydrodeoxygenation method and application thereof
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The invention belongs to the technical field of medicines, and discloses an aromatic compound hydrogenation and hydrodeoxygenation method under mild conditions and application of the method in hydrogenation and hydrodeoxygenation reactions of the aromatic compounds and related mixtures. Specifically, the method comprises the following steps: contacting the aromatic compound or a mixture containing the aromatic compound with a catalyst and hydrogen with proper pressure in a solvent under a proper temperature condition, and reacting the hydrogen, the solvent and the aromatic compound under the action of the catalyst to obtain a corresponding hydrogenation product or/and a hydrodeoxygenation product without an oxygen-containing substituent group. The invention also discloses specific implementation conditions of the method and an aromatic compound structure type applicable to the method. The hydrogenation and hydrodeoxygenation reaction method used in the invention has the advantages of mild reaction conditions, high hydrodeoxygenation efficiency, wide substrate applicability, convenient post-treatment, and good laboratory and industrial application prospects.
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Paragraph 0094-0096; 0098; 0100-0104
(2021/05/29)
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- Reductive amination of ketones/aldehydes with amines using BH3N(C2H5)3as a reductant
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Herein, we report the first example of efficient reductive amination of ketones/aldehydes with amines using BH3N(C2H5)3 as a catalyst and a reductant under mild conditions, affording various tertiary and secondary amines in excellent yields. A mechanistic study indicates that BH3N(C2H5)3 plays a dual function role of promoting imine and iminium formation and serving as a reductant in reductive amination. This journal is
- Zou, Qizhuang,Liu, Fei,Zhao, Tianxiang,Hu, Xingbang
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supporting information
p. 8588 - 8591
(2021/09/04)
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- One-pot synthesis of cyclohexylamine and: N -aryl pyrroles via hydrogenation of nitroarenes over the Pd0.5Ru0.5-PVP catalyst
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The direct synthesis of cyclohexylamine via the hydrogenation of nitrobenzene over monometallic (Pd, Ru or Rh) and bimetallic (PdxRu1-x) catalysts was studied. The Pd0.5Ru0.5-PVP catalyst was the most effective catalyst for this reaction. The catalyst can be reused and applied for the synthesis of N-aryl pyrroles and quinoxalines from nitrobenzenes.
- Chaudhari, Chandan,Sato, Katsutoshi,Ikeda, Yasuyuki,Terada, Kenji,Abe, Naoya,Nagaoka, Katsutoshi
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supporting information
p. 9743 - 9746
(2021/06/15)
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- Lithium Dicyclohexylamide in Transition-Metal-Free Fischer-Tropsch Chemistry
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Lithium dicyclohexylamide (Cy2NLi) reacts with syn-gas or CO to generate transient intermediates with carbene character, which are capable of reacting further with CO or H2, effecting sequential C-C and C-H bond formations from CO or H2, thus providing a transition-metal-free avenue to the fundamental reactions of the Fischer-Tropsch process. Further experimental and computational data indicate that reactions with CO and H2 are thermodynamically accessible, with a kinetic bias toward CO homologation.
- Xu, Maotong,Qu, Zheng-Wang,Grimme, Stefan,Stephan, Douglas W.
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supporting information
p. 634 - 638
(2021/01/25)
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- Preparation method of cyclohexanone oxime
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The invention relates to a preparation method of cyclohexanone oxime. The method comprises the following steps: carrying out partial oxidation reaction on cyclohexylamine and molecular oxygen under the action of a catalyst to obtain an oxidation reaction product consisting of cyclohexanone oxime, a byproduct and possibly unconverted cyclohexylamine; and then treating the oxidation reaction product in one of the following modes: (i) carrying out hydrogenation amination reaction with H2 and NH3 at the same time or carrying out hydrogenation and amination reaction in sequence under the action of a catalyst without separation or after part or all of water in the oxidation reaction product is separated, and then carrying out separation to obtain cyclohexanone oxime; and (ii) carrying out hydrogenation reaction with H2 under the action of a catalyst without separation or after part or all of water is separated out, and then carrying out separation to obtain the cyclohexanone oxime. The method disclosed by the invention has the characteristics of short process flow, small occupied area and investment, low material consumption and energy consumption (low cost), simplicity and convenience in operation, environment friendliness and the like.
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Paragraph 0073; 0075-0076
(2021/06/13)
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- The benzyl can be selectively removed by visible light or near visible light. Method for protecting allyl and propargyl group
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The invention provides a method for selectively removing benzyl, allyl and propargyl protecting groups by visible light or near visible light, namely a substrate containing benzyl, allyl or propargyl protecting groups. The method has the advantages of simple operation, safe and clean visible light or near visible light as excitation conditions, cheap and easily available reagents, high reaction yield, high reaction chemistry and regional selectivity, and is suitable for selective removal of benzyl, allyl and propargyl protecting groups in various substrates.
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Paragraph 0023
(2021/10/16)
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- Barium and titanium dithiocarbamates as precursors for colloidal nanocrystals of emerging optoelectronic materials
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The synthesis and structures of N,N-dialkyldithiocarbamate complexes of barium are reported; the compounds crystallize as one-dimensional coordination polymers. In combination with a titanium dithiocarbamate precursor, the compounds are demonstrated as competent single-source precursors for the solution-based preparation of colloidal BaTiS3 nanorods. This journal is
- Creutz, Sidney E.,Donnadieu, Bruno,Ingram, Nicole E.,Jordan, Brian J.
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p. 15978 - 15982
(2021/11/27)
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- Production of alkoxyl-functionalized cyclohexylamines from lignin-derived guaiacols
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The transformation of renewable lignin-based platform chemicals into value-added nitrogen-containing compounds is an emerging strategy for lignin utilization. However, multi-reactive sites on these platform chemicals make it challenging to control the product selectivity, thereby resulting in limited success. In this work, we developed the reductive-coupling of guaiacol, a typical lignin-based platform chemical, with amines and H2 to synthesize methoxy-functionalized cyclohexylamines. It was demonstrated that Pd/C was a very efficient catalyst for this kind of reaction, and high yields of the target products can be obtained. Notably, this methodology can be applied for the reductive-coupling of various guaiacol analogues with amines to synthesize alkoxyl-functionalized cyclohexylamines with high yields. A mechanism study revealed that the reaction occurred through the generation of 2-methoxycyclohexanone and its subsequent reductive amination. This journal is
- Han, Buxing,He, Mingyuan,Mei, Xuelei,Song, Jinliang,Wu, Haihong,Wu, Wei,Xu, Caiyun,Xu, Jiao,Zhang, Kaili,Zheng, Bingxiao
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supporting information
p. 8441 - 8447
(2021/11/17)
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- A Lewis Base Nucleofugality Parameter, NFB, and Its Application in an Analysis of MIDA-Boronate Hydrolysis Kinetics
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The kinetics of quinuclidine displacement of BH3 from a wide range of Lewis base borane adducts have been measured. Parameterization of these rates has enabled the development of a nucleofugality scale (NFB), shown to quantify and predict the leaving group ability of a range of other Lewis bases. Additivity observed across a number of series R′3-nRnX (X = P, N; R′ = aryl, alkyl) has allowed the formulation of related substituent parameters (nfPB, nfAB), providing a means of calculating NFB values for a range of Lewis bases that extends far beyond those experimentally derived. The utility of the nucleofugality parameter is explored by the correlation of the substituent parameter nfPB with the hydrolyses rates of a series of alkyl and aryl MIDA boronates under neutral conditions. This has allowed the identification of MIDA boronates with heteroatoms proximal to the reacting center, showing unusual kinetic lability or stability to hydrolysis.
- García-Domínguez, Andrés,Gonzalez, Jorge A.,Leach, Andrew G.,Lloyd-Jones, Guy C.,Nichol, Gary S.,Taylor, Nicholas P.
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supporting information
(2022/01/04)
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- Amination of aliphatic alcohols with urea catalyzed by ruthenium complexes: effect of supporting ligands
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In the present study, ruthenium-catalyzed amination of alcohols by urea as a convenient ammonia carrier in the presence of free diphosphine ligands has been described. A number of ruthenium-phosphine complexes have been studied among which, [(Cp)RuCl(dppe)] was found as an efficient catalyst for alcohol amination reaction. The crystal structures of two new half-sandwich ruthenium complexes, [(Cp)RuCl(dppe)] and [(C6H6)RuCl2(PHEt2)], were determined by X-ray crystallographic analysis. Also the effect of using different supporting phosphines, ratio of raw materials and reaction temperature on conversion and selectivity was investigated. Under optimum reaction conditions high conversion (98percent) and chemo-selectivity toward secondary amines were obtained.
- Dindar, Sara,Nemati Kharat, Ali
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- One-pot dual catalysis for the hydrogenation of heteroarenes and arenes
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A simple dinuclear monohydrido bridged ruthenium complex [{(η6-p-cymene)RuCl}2(μ-H-μ-Cl)] acts as an efficient and selective catalyst for the hydrogenation of various heteroarenes and arenes. The nature of the catalytically active species was investigated using a combination of techniques including in situ reaction monitoring, kinetic studies, quantitative poisoning experiments and electron microscopy, evidencing a dual reactivity. The results suggest that the hydrogenation of heteroarenes proceeds via molecular catalysis. In particular, monitoring the reaction progress by NMR spectroscopy indicates that [{(η6-p-cymene)RuCl}2(μ-H-μ-Cl)] is transformed into monomeric ruthenium intermediates, which upon subsequent activation of dihydrogen and hydride transfer accomplish the hydrogenation of heteroarenes under homogeneous conditions. In contrast, carbocyclic aryl motifs are hydrogenated via a heterogeneous pathway, by in situ generated ruthenium nanoparticles. Remarkably, these hydrogenation reactions can be performed using molecular hydrogen under solvent-free conditions or with 1,4-dioxane, and thus give access to a broad range of saturated heterocycles and carbocycles while generating no waste.
- Chatterjee, Basujit,Kalsi, Deepti,Kaithal, Akash,Bordet, Alexis,Leitner, Walter,Gunanathan, Chidambaram
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p. 5163 - 5170
(2020/09/07)
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- Preparation method of cyclohexanone-oxime
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The invention relates to a preparation method of cyclohexanone-oxime. The method mainly comprises three synthesis steps of catalytic aniline or nitrobenzene hydrogenation, cyclohexylamine oxidation and byproduct amination: (1) carrying out a hydrogenation reaction on aniline or nitrobenzene and hydrogen under the action of a catalyst to generate cyclohexylamine and a small amount of byproduct-A, and separating the byproduct-A and possibly incompletely converted aniline to obtain cyclohexylamine; (2) carrying out an oxidation reaction on the cyclohexylamine obtained in the step (1) and molecular oxygen under the action of a catalyst to obtain an oxidation reaction product mainly composed of cyclohexanone-oxime, a small amount of by-product-B and possibly unconverted cyclohexylamine; and (3)directly carrying out an amination reaction on the oxidation reaction product obtained in the step (2), ammonia and hydrogen under the action of a catalyst without separation, completely converting the byproduct-B into cyclohexylamine, and separating the cyclohexylamine to obtain cyclohexanone-oxime. According to the method, the yield of cyclohexanone-oxime can be remarkably increased, and the energy consumption and the cost of cyclohexanone-oxime production can be remarkably reduced.
- -
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Paragraph 0040
(2020/06/30)
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- 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
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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.
- Pietrobon, L.,Pontello, R.,Ronchin, L.,Sadraoui, C.,Tosetto, C.,Vavasori, A.
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- AlCl3 immobilized on silicic acid as efficient Lewis acid catalyst for highly selective preparation of dicyclohexylamine from the vapor phase hydroamination of cyclohexene with cyclohexylamine
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An efficient and stable Lewis acid catalyst silicic acid (SA)-immobilized AlCl3 (AlCl3-SA) has been successfully prepared by the chemical bonding method in this work. The results indicated that the immobilized 15percentAlCl3-SA exhibited excellent catalytic performance and stability in the vapor phase hydroamination of cyclohexene with cyclohexylamine. 58.5percent cyclohexene conversion with 98.7percent selectivity to dicyclohexylamine was still maintained after running for over 150 h, and the space time yield of dicyclohexylamine was 142.6 mol/h·m3. The developed AlCl3-SA catalyst had the advantages of low cost and long-time stable activity. Maybe this work provides a promising approach for hydroamination of olefins to amines.
- Ai, Qiuhong,Jian, Jian,Liu, Pingle,Luo, He'an,Wen, Jingbin,You, Kuiyi,Zhao, Fangfang
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- Cogeneration cyclohexylamine and dicyclohexylamine method and used for the method of the catalyst system
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The invention discloses a cogeneration cyclohexylamine and dicyclohexylamine method and used for the method of the catalyst system. The method comprises the following steps: (1) the raw material aniline, cyclohexanone, ammonia, a hydrogen filling load Rh - Ni catalyst 1st stage reactor, to obtain the 1st reaction solution; (2) 1st reaction solution through the filling load Rh - Co catalyst 2nd stage reactor, containing the cyclohexylamine and dicyclohexylamine of reaction solution. The advantage of this invention is cheap raw material, the conversion is high, good selectivity of the product, of a catalyst is long, the procedure is simple, the continuous process, a high degree of automation, low labor intensity, low production cost, can be combined to obtain high added value bicyclic cyclohexylamine, and can be according to the demand of the market of the product, by changing the reaction conditions to adjust the composition of the product, and is suitable for industrial large-scale production.
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Page/Page column 0061-0066
(2019/04/04)
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- Cobalt-Nanoparticles Catalyzed Efficient and Selective Hydrogenation of Aromatic Hydrocarbons
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The development of inexpensive and practical catalysts for arene hydrogenations is key for future valorizations of this general feedstock. Here, we report the development of cobalt nanoparticles supported on silica as selective and general catalysts for such reactions. The specific nanoparticles were prepared by assembling cobalt-pyromellitic acid-piperazine coordination polymer on commercial silica and subsequent pyrolysis. Applying the optimal nanocatalyst, industrial bulk, substituted, and functionalized arenes as well as polycyclic aromatic hydrocarbons are selectively hydrogenated to obtain cyclohexane-based compounds under industrially viable and scalable conditions. The applicability of this hydrogenation methodology is presented for the storage of H2 in liquid organic hydrogen carriers.
- Murugesan, Kathiravan,Senthamarai, Thirusangumurugan,Alshammari, Ahmad S.,Altamimi, Rashid M.,Kreyenschulte, Carsten,Pohl, Marga-Martina,Lund, Henrik,Jagadeesh, Rajenahally V.,Beller, Matthias
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p. 8581 - 8591
(2019/09/12)
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- Electrocatalytic Dealkylation of Amines Mediated by Ferrocene
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The homogeneous catalytic oxidation of dicyclohexylamine (DCHA), N,N-dimethylcyclohexylamine (DMCHA) and N,N-dicyclohexylmethylamine (DCHMA) has been investigated in the presence of electrochemically generated ferrocenium ions as the catalyst. Mechanistic details for this electrocatalytic process have been scrutinized with the use of cyclic voltammetry, bulk electrolysis, and digital simulations techniques. A one-electron catalytic process between ferrocene and the respective amines was observed. The products obtained from bulk electrolysis were isolated and identified by FTIR, 1H and 13C NMR spectroscopy, and mass spectrometry. Both DCHMA and DMCHA proceed to yield a secondary amine product by the elimination of one methyl group. In the absence of this group, as in the case of DCHA, the cycloalkyl group is then eliminated. The catalytic efficiency and the second-order rate constants were estimated and found to follow the order DCHA ≤ DMCHA DCHMA. The results presented in this work should open up a new avenue to achieve simple, low-cost, and efficient amine oxidation, which could be useful in several areas of chemistry.
- Torriero, Angel A. J.,Morda, Joanne,Saw, Jessica
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p. 4280 - 4287
(2019/11/11)
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- Anti-Markovnikov Hydroamination of Unactivated Alkenes with Primary Alkyl Amines
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We report here a photocatalytic method for the intermolecular anti-Markovnikov hydroamination of unactivated olefins with primary alkyl amines to selectively furnish secondary amine products. These reactions proceed through aminium radical cation (ARC) intermediates and occur at room temperature under visible light irradiation in the presence of an iridium photocatalyst and an aryl thiol hydrogen atom donor. Despite the presence of excess olefin, high selectivities are observed for secondary over tertiary amine products, even though the secondary amines are established substrates for ARC-based olefin amination under similar conditions.
- Miller, David C.,Ganley, Jacob M.,Musacchio, Andrew J.,Sherwood, Trevor C.,Ewing, William R.,Knowles, Robert R.
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supporting information
p. 16590 - 16594
(2019/11/03)
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- Catalytic Transfer Hydrodebenzylation with Low Palladium Loading
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A highly-efficient catalytic system for hydrodebenzylation reaction is described. The cleavage of O-benzyl and N-benzyl protecting groups was performed using an uncommonly low palladium loading (0.02–0.3 mol%; TON up to 5000) in a relatively short reaction time. The approach was used for a variety of substrates including pharmaceutically important precursors, and gram-scale deprotection reaction was shown. Transfer conditions together with easy-to-make Pd/C catalyst are the key features of this debenzylation scheme. (Figure presented.).
- Yakukhnov, Sergey A.,Ananikov, Valentine P.
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supporting information
p. 4781 - 4789
(2019/09/16)
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- Polysilane-Immobilized Rh-Pt Bimetallic Nanoparticles as Powerful Arene Hydrogenation Catalysts: Synthesis, Reactions under Batch and Flow Conditions and Reaction Mechanism
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Hydrogenation of arenes is an important reaction not only for hydrogen storage and transport but also for the synthesis of functional molecules such as pharmaceuticals and biologically active compounds. Here, we describe the development of heterogeneous Rh-Pt bimetallic nanoparticle catalysts for the hydrogenation of arenes with inexpensive polysilane as support. The catalysts could be used in both batch and continuous-flow systems with high performance under mild conditions and showed wide substrate generality. In the continuous-flow system, the product could be obtained by simply passing the substrate and 1 atm H2 through a column packed with the catalyst. Remarkably, much higher catalytic performance was observed in the flow system than in the batch system, and extremely strong durability under continuous-flow conditions was demonstrated (>50 days continuous run; turnover number >3.4 × 105). Furthermore, details of the reaction mechanisms and the origin of different kinetics in batch and flow were studied, and the obtained knowledge was applied to develop completely selective arene hydrogenation of compounds containing two aromatic rings toward the synthesis of an active pharmaceutical ingredient.
- Miyamura, Hiroyuki,Suzuki, Aya,Yasukawa, Tomohiro,Kobayashi, Shu
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supporting information
p. 11325 - 11334
(2018/09/06)
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- Synthesis of Symmetric and Unsymmetric Secondary Amines from the Ligand-Promoted Ruthenium-Catalyzed Deaminative Coupling Reaction of Primary Amines
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The catalytic system generated in situ from the tetranuclear Ru-H complex with a catechol ligand (1/L1) was found to be effective for the direct deaminative coupling of two primary amines to form secondary amines. The catalyst 1/L1 was highly chemoselective for promoting the coupling of two different primary amines to afford unsymmetric secondary amines. The analogous coupling of aniline with primary amines formed aryl-substituted secondary amines. The treatment of aniline-d7 with 4-methoxybenzylamine led to the coupling product with significant deuterium incorporation on CH2 (18% D). The most pronounced carbon isotope effect was observed on the α-carbon of the product isolated from the coupling reaction of 4-methoxybenzylamine (C(1) = 1.015(2)). A Hammett plot was constructed from measuring the rates of the coupling reaction of 4-methoxyaniline with a series of para-substituted benzylamines 4-X-C6H4CH2NH2 (X = OMe, Me, H, F, CF3) (ρ = -0.79 ± 0.1). A plausible mechanistic scheme has been proposed for the coupling reaction on the basis of these results. The catalytic coupling method provides an operationally simple and chemoselective synthesis of secondary amine products without using any reactive reagents or forming wasteful byproducts.
- Arachchige, Pandula T. Kirinde,Lee, Hanbin,Yi, Chae S.
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p. 4932 - 4947
(2018/05/08)
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- The Rhodium Catalysed Direct Conversion of Phenols to Primary Cyclohexylamines
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Cyclohexylamines are important intermediates in chemical industry, which are currently produced from petrochemical sources. Phenols, however, are an attractive sustainable feedstock. We here demonstrate the transformation of phenols with ammonia to primary cyclohexylamines. In contrast to previously reported chemistry which used palladium catalysts, we here show that rhodium is an excellent catalyst for the formation of primary cyclohexylamines. Different parameters were studied and it was shown that the reaction is applicable to a scope of phenolic compounds providing high selectivity.
- Tomkins, Patrick,Valgaeren, Carlot,Adriaensen, Koen,Cuypers, Thomas,Vos, Dirk E. De
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p. 3689 - 3693
(2018/07/31)
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- Amide: Versus amine ligand paradigm in the direct amination of alcohols with Ru-PNP complexes
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The catalytic activity of a series of Ru-PNP pincer ligand complexes was studied in the direct amination of alcohols with ammonia. It turned out that all complexes of PNP ligands bearing a secondary amine showed no activity in this hydrogen-shuttling reaction sequence, while all complexes of homologous ligands bearing a tertiary amine gave active catalysts. Further comparative studies on catalysts bearing an acridine-based PNP pincer ligand and a PNP ligand of the Xantphos family provided valuable mechanistic insight that led to the design of a highly active catalyst. It appears that in the group of ligands studied here only ligands that do not form stable Ru-amido complexes are active alcohol amination catalysts.
- Pingen, Dennis,Choi, Jong-Hoo,Allen, Henry,Murray, George,Ganji, Prasad,Van Leeuwen, Piet W. N. M.,Prechtl, Martin H. G.,Vogt, Dieter
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p. 3969 - 3976
(2018/08/16)
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- Conversion of Primary Amines to Symmetrical Secondary and Tertiary Amines using a Co-Rh Heterobimetallic Nanocatalyst
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Symmetrical tertiary amines have been efficiently realized from amine and secondary amines via deaminated homocoupling with heterogeneous bimetallic Co2Rh2/C as catalyst (molar ratio Co:Rh=2:2). Unsymmetric secondary anilines were produced from the reaction of anilines with symmetric tertiary amines. The Co2Rh2/C catalyst exhibited very high catalytic activity towards a wide range of amines and could be conveniently recycled ten times without considerable leaching. (Figure presented.).
- Chung, Hyunho,Han, Seulgi,Chung, Young Keun,Park, Ji Hoon
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supporting information
p. 1267 - 1272
(2018/02/12)
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- Solvent-Driven Selectivity Control to Either Anilines or Dicyclohexylamines in Hydrogenation of Nitroarenes over a Bifunctional Pd/MIL-101 Catalyst
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The hydrogenation of nitroarenes is one of the most important strategies to produce the corresponding anilines and dicyclohexylamines, both of which are the fundamental raw materials in the synthesis of various pharmaceuticals and fine chemicals. Nevertheless, it is still a great challenge to develop a highly versatile and flexible catalytic system to selectively generate desired amines. Herein, we report the solvent-driven selectivity control over a bifunctional Pd/MIL-101 catalyst for the hydrogenation of nitrobenzene. An almost full selectivity of 99.9% to aniline or a surprising selectivity of 99.1% to dicyclohexylamine is achieved by using dimethylformamide (DMF, a polar solvent) or n-hexane (an apolar solvent) as the solvents, respectively. It is proposed that the polarity of solvents can effectively regulate the linkage between reactants/intermediates and Pd/MIL-101, affording controllable selectivities of aniline or dicyclohexylamine at will. In addition, the Lewis acid sites in Pd/MIL-101 can also effectively activate the aromatic ring and accelerate the cross-coupling reaction of amine. This solvent-driven catalytic system also exhibits good recyclability and compatibility for a wide substrate scope in both DMF and n-hexane, showing great promise for industrial applications. This study might open an avenue for the hydrogenation of nitroarenes to selectively produce anilines or dicyclohexylamines by simply regulating the solvent polarity over a bifunctional catalyst system.
- Chen, Xiaodong,Shen, Kui,Ding, Danni,Chen, Junying,Fan, Ting,Wu, Rongfang,Li, Yingwei
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p. 10641 - 10648
(2018/10/31)
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- Colloid and Nanosized Catalysts in Organic Synthesis: XVIII.1 Disproportionation and Cross-Coupling of Amines During Catalysis with Immobilized Nickel Nanoparticles
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It has been stated that immobilized nickel nanoparticles catalyze disproportionation and cross-coupling of amines. The influence of the support on the catalysis of these properties in the in plug-flow reactor has been studied. The use of active carbon as the support has been found advantageous for the cross-coupling of amines, whereas alumina was a better support for the disproportionation reaction.
- Popov, Yu. V.,Mokhov,Latyshova,Nebykov,Panov,Davydova
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p. 2757 - 2761
(2018/02/21)
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- Copper-Catalyzed Alkylation of Aliphatic Amines Induced by Visible Light
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Although the alkylation of an amine by an alkyl halide serves as a textbook example of a nucleophilic substitution reaction, the selective mono-alkylation of aliphatic amines by unactivated, hindered halides persists as a largely unsolved challenge in organic synthesis. We report herein that primary aliphatic amines can be cleanly mono-alkylated by unactivated secondary alkyl iodides in the presence of visible light and a copper catalyst. The method operates under mild conditions (-10 °C), displays good functional-group compatibility, and employs commercially available catalyst components. A trapping experiment with TEMPO is consistent with C-N bond formation via an alkyl radical in an out-of-cage process.
- Matier, Carson D.,Schwaben, Jonas,Peters, Jonas C.,Fu, Gregory C.
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supporting information
p. 17707 - 17710
(2017/12/26)
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- Colloid and nanosized catalysts in organic synthesis: XVII. Reductive amination of carbonitriles in the presence of supported nickel nanoparticles
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Reductive amination of carbonitriles catalyzed by nickel nanoparticles applied onto a solid support in a plug flow reactor in the gas phase or the gas–liquid–solid catalyst system occurs at atmospheric pressure of hydrogen affording the nonsymmetrical secondary or tertiary amines. The effect of the support type on the target product yield and conversion of the substrate has been studied.
- Popov, Yu. V.,Mokhov,Latyshova,Panov,Shirkhanyan
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p. 2546 - 2551
(2017/12/26)
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- An improved and one-pot procedure to the synthesis of symmetric amines by domino reactions of 5-methyl-1,3,4-thiadiazole-2-amine, a new nitrogen atom donor, and alkyl halides
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Abstract: A new one-pot method has been introduced in this work for the synthesis of symmetrical primary, secondary, and tertiary alkyl amines from alkyl halides and 5-methyl-1,3,4-thiadiazole-2-amine as a nitrogen-transfer reagent. In this method, all three types of amines have been successfully prepared after changing the ratio of substrates and base control. In addition to the introduction of a new nitrogen-transfer reagent, other important features of this work include normal atmospheric conditions and excellent yields under mild reaction conditions.
- Soleiman-Beigi, Mohammad,Mohammadi, Fariba
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p. 2123 - 2128
(2017/10/26)
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- Palladium-Catalyzed Synthesis of N-Cyclohexyl Anilines from Phenols with Hydrazine or Hydroxylamine via N-N/O Cleavage
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Direct access to amines from biomass-based phenols via deoxygenative transformation remains greatly challenging in organic synthesis. Herein, we present a palladium-catalyzed deoxygenative amination of phenols (and their benzyl ether) with hydrazine as nitrogen source. The hydroxylamine/formic acid can be substituted for hydrazine in some cases. This deoxyamination features the involvement of a complex C?O bond and N?N/O bond-cleavage process and allows for the construction of N-substituted cyclohexyl anilines from an array of phenols by finely controlling the reaction conditions in moderate to good yields. (Figure presented.).
- Li, Jiang-Sheng,Qiu, Zihang,Li, Chao-Jun
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supporting information
p. 3648 - 3653
(2017/09/13)
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- Pd/C-Al-water facilitated selective reduction of a broad variety of functional groups
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The chemoselective reduction of a broad variety of functional groups by a Pd/C-Al-H2O system is described. The reduction is based on the reaction of Al with the solvent water that in situ produces hydrogen that is utilized by the supported Pd catalyst toward the hydrogenation of the target functional groups. The hydrogenations are carried out under mild conditions and provided the products in high yields and selectivity. The reduction system appeared to be effective for a broad range of functional groups, including C-C, C-N, C-O and N-O multiple bonds, aromatic rings, hydrogenolysis of C-O, C-N and C-Halogen bonds. The appropriate selection of the reaction conditions allowed the selective preparation of different products from the same substrate. The simplicity, cost, tunability and the environmentally benign character of the catalytic system offer numerous advantages over the currently available methods.
- Sch?fer,Ellstrom,Cho,T?r?k
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p. 1230 - 1234
(2017/03/20)
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- Catalyst-free synthesis of amines from cyclic ketones and formamides in superheated water
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A novel and environmentally benign protocol for the synthesis of amines from cyclic ketones and formamides is demonstrated. The reaction proceeds under catalyst-free and superheated water conditions and yields range from poor to excellent.
- Kumar, Macharla Arun,Srujana, Kodumuri,Swamy, Peraka,Naresh, Mameda,Durgaiah, Chevella,Rammurthy, Banothu,Narender, Nama
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supporting information
p. 516 - 522
(2016/05/02)
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- A ruthenium racemisation catalyst for the synthesis of primary amines from secondary amines
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A Ru-based half sandwich complex used in amine and alcohol racemization reactions was found to be active in the splitting of secondary amines to primary amines using NH3. Conversions up to 80% along with very high selectivities were achieved. However, after about 80% conversion the catalyst lost activity. Similar to Shvo's catalyst, the complex might deactivate under the influence of ammonia. It was revealed that not NH3 but mainly the primary amine is responsible for the deactivation.
- Pingen, Dennis,Altinta?, ?i?dem,Rudolf Schaller, Max,Vogt, Dieter
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p. 11765 - 11771
(2016/07/28)
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- N-Alkylation of amines with phenols over highly active heterogeneous palladium hydride catalysts
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Phenols are directly converted to secondary amines in considerable yield via hydrogenation and amination tandem reaction over Al2O3 supported palladium hydride (PdHx) bi-functional catalyst. Note that this system proceeds efficiently with mild conditions under H2 atmosphere, which was difficult to achieve in previous reports. The catalyst and the mechanism of reaction are both studied. Furthermore, various secondary amines can be formed in good yields under this conversion system.
- Yan, Long,Liu, Xin-Xin,Fu, Yao
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p. 109702 - 109705
(2016/11/30)
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- An efficient method for the production of cyclohexylamine from cyclohexanone and ammonia over Cu-Cr-La/-Al2O3
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The reductive amination of cyclohexanone with ammonia over Cu-Cr-La/-Al2O3 was investigated. It was found that a proper solvent with high solubility of ammonia and 4A molecular sieves for the elimination of generated water contributed to the formation of cyclohexylamine in the premixing process. In addition, the addition of ammonia in the fixedbed reactor could obviously improve the conversion of cyclohexanone to cyclohexylamine. Finally, reaction conditions including reaction temperature, hydrogen pressure and charging rate of the premix were optimized. Under the optimized conditions, cyclohexylamine was obtained in 83.06% yield.
- Qin, Shuanglin,Wang, Pan,Huang, Shuangping,Liu, Shuai,Wang, Gaopeng,Wang, Liping,Sun, Meng,Wang, Xiaoji
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p. 493 - 498
(2016/01/12)
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- The distinct role of the flexible polymer matrix in catalytic conversions over immobilised nanoparticles
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Polymer resins with immobilized metal nanoparticles represent highly promising materials for attaining intelligent and ecologically friendly catalysts. Control of the dynamic swelling behaviour of the polymer resins enables the on/off-switching of the activity of the encapsulated metal nanoparticles, thereby allowing conversion and selectivity to be controlled at a specific time of the chemical reaction. This paper presents a study on the distinct role of the polymer support. Here, the hydrogenation of nitrobenzene was chosen as a model reaction, and nanoparticles of different metals were taken into account. The course of the reaction revealed the essential role of the polymer resins in controlling the diffusion, in particular of the reagents, to and from the catalytically active sites on the surface of the nanoparticles thereby influencing the catalytic activity of the metal and opening up a new approach to catalytic engineering.
- Martinuzzi, Stefano,Cozzula, Daniela,Centomo, Paulo,Zecca, Marco,Müller, Thomas E.
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p. 56181 - 56188
(2015/07/15)
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- Ruthenium-Na2CO3-catalyzed one-pot synthesis of ring-hydrogenated carbamates from aromatic amines and organic carbonates under H2
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A facile and efficient one-pot procedure for the synthesis of ring hydrogenated carbamates from aromatic amine and alkylene carbonate under H2 gas pressure has been developed using a heterogeneous catalyst system comprising ruthenium and alkali metal carbonates. The effects of temperature, H2 pressure, catalyst (types of loaded metal and their supports), molar ratio of substrate/catalyst, and solvent were also investigated. Among the alkali metal carbonates, the sodium carbonate was found as best promoter for nucleophilic attack and ring-opening (NARO) reaction and thus increased the yield of ring hydrogenated carbamate up to 88% when using Ru/C as ring hydrogenation (RH) catalyst. This catalyst system could be reused at least five times without signi?cant loss of activity, which makes this process cost-effective and eco-friendly.
- Cho, Jin Ku,Kim, Hoon Sik,Kim, Yong Jin,Mishra, Vivek,Shin, Seung-Han,Suh, Young-Woong
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