- Reaction of Phospholes with Aldimines: A One-Step Synthesis of Chelating, Alpha-C2-Bridged Biphospholes
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Phospholes react with aldimines at 170°C in the presence of mild Lewis acids to give C2-bridged biphospholes in good yields. The mechanism includes a series of [1,5] shifts of the P-substituents around the phosphole ring, a P-H + aldimine condensation, and the formation of a transient three-membered ring that dimerizes.
- Hu, Zhengsong,Li, Zongyang,Zhao, Kang,Tian, Rongqiang,Duan, Zheng,Mathey, Fran?ois
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- A Selective Electrocatalytic Cleavage of the Benzyloxycarbonyl Group from Peptides
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An electrosynthetic procedure for the cleavage of the benzyloxycarbonyl group from protected amino acids and peptides is described.It is based on the use of a high surface area palladium cathode in methanol/acetic acid and gives an excellent selectivity under very mild conditions.
- Casadei, M. Antonietta,Pletcher, D.
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- Formal asymmetric biocatalytic reductive amination
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All for one: A combination of three biocatalysts (ω-transaminase, alanine dehydrogenase, and an enzyme such as formate dehydrogenase for cofactor recycling) catalyze a cascade to achieve the asymmetric transformation of a ketone into a primary α-chiral unprotected amine through a formal stereoselective reductive amination (see scheme). Only ammonia and the reducing agent (formate) are consumed during this reaction. (Chemical Equation Presented).
- Koszelewski, Dominik,Lavandera, Ivan,Clay, Dorina,Guebitz, Georg M.,Rozzell, David,Kroutil, Wolfgang
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- Commercial catalysts screening for liquid phase nitrobenzene hydrogenation
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In this work, a series of commercially available materials was screened for the catalytic hydrogenation of nitrobenzene (NB). The materials revealed different performances, particularly different activities in what concerns the NB conversion, and notably diverse selectivities towards the industrially desired reaction product, aniline (ANL). The catalysts' active phases are based on Pd and Ni (respectively groups I and II), namely 1 wt.% Pd/Al2O3 (catalyst I.1), 0.3 wt.% Pd/Al2O3 (catalyst I.2), 0.3 wt.% Pd/Al2O3 (catalyst I.3), and 50 wt.% NiO/(Al2O3 + SiO2) (catalyst II.1). The fresh and used materials were characterized by several physical-chemical techniques, specifically scanning electron microscopy (SEM), high resolution transmission electron microscopy (HRTEM), nitrogen adsorption (with BET surface area determination), X-ray diffraction (XRD), H2 temperature-programmed reduction (TPR), inductively coupled plasma mass spectrometry (ICP-MS) and elemental (CHNS) analysis. It was shown that the catalysts are stable in the conditions studied and no deactivation was found. The characterization results allowed explaining the catalytic behavior of the tested materials. In particular, catalyst I.1 was found to be the less active, probably due to its much lower BET surface area (and larger Pd particle size). On the other hand, catalyst I.2 was the more active, which was well correlated to the smaller average particle size (along with narrower Pd particle size distribution) and smaller pellet size, although the active metal content is low. Finally, it was observed that catalyst II.1 is the most selective towards light by-products (benzene (Bz), cyclohexylamine (CHA), cyclohexanol (CHOL) and cyclohexanone (CHONA)), probably due to its lower pore size dimensions.
- Couto, Clara Sá,Madeira, Luis M.,Nunes, Clemente Pedro,Araújo, Paulo
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- Anti-Markovnikov Hydroamination of Alkenes with Aqueous Ammonia by Metal-Loaded Titanium Oxide Photocatalyst
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A completely new route was established to synthesize valuable primary amines from alkenes by using aqueous ammonia, that is, a simple photocatalytic hydroamination of alkenes using aqueous ammonia with a metal-loaded TiO2 photocatalyst. Although the photochemical hydroamination prefers to form amines according to the Markovnikov rule, the new photocatalytic hydroamination gives anti-Markovnikov products predominantly. With an Au-loaded TiO2 photocatalyst, the amine yield reached up to 93% and the regioselectivity of anti-Markovnikov products was above 98%. The reaction mechanism was proposed for the new photocatalytic hydroamination.
- Park, Soyeong,Jeong, Jaeyoung,Fujita, Ken-Ichi,Yamamoto, Akira,Yoshida, Hisao
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- Poly(propylene sulfide)-borane: Convenient and versatile reagent for organic synthesis
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Poly(trimethylene sulfide)-borane adduct has been used as an efficient borane reagent in hydroboration reactions to produce various organoboranes, which have then been used without isolation in further reactions that involve single, double and triple migrations of alkyl groups. The presence of the polymer causes no problems, but there are practical advantages associated with its use, including lack of odour and easy recoverability.
- Smith, Keith,Balakit, Asim A.,El-Hiti, Gamal A.
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- Doped ordered mesoporous carbons as novel, selective electrocatalysts for the reduction of nitrobenzene to aniline
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Ordered mesoporous carbons (OMCs) doped with nitrogen, phosphorus or boron were synthesised through a two-step nanocasting method and studied as electrocatalysts for the reduction of nitrobenzene to aniline in a half-cell setup. The nature of the dopant played a crucial role in the electrocatalytic performance of the doped OMCs, which was monitored by LSV with a rotating disk electrode setup. The incorporation of boron generated the electrocatalysts with the highest kinetic current density, whereas the incorporation of phosphorus led to the lowest overpotential. Doping with nitrogen led to intermediate behaviour in terms of onset potential and kinetic current density, but provided the highest selectivity towards aniline, thus resulting in the most promising electrocatalyst developed in this study. Density functional theory calculations allowed explaining the observed difference in the onset potentials between the various doped OMCs, and indicated that both graphitic N and pyrdinic N can generate active sites in the N-doped electrocatalyst. A chronoamperometric experiment over N-doped OMC performed at -0.75 V vs. Fc/Fc+ in an acidic environment, resulted in a conversion of 61% with an overall selectivity of 87% to aniline. These are the highest activity and selectivity ever reported for an electrocatalyst for the reduction of nitrobenzene to aniline, making N-doped OMC a promising candidate for the electrochemical cogeneration of this industrially relevant product and electricity in a fuel cell setup.
- Daems, Nick,Risplendi, Francesca,Baert, Kitty,Hubin, Annick,Vankelecom, Ivo F. J.,Cicero, Giancarlo,Pescarmona, Paolo P.
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- Selective reductions. Part 60: Chemoselective reduction of organyl azides with dichloroborane-dimethyl sulfide
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The rate and stoichiometry of the reduction of an organyl azide with BH3·THF was examined under standardized conditions at room temperature. Borane derivatives, such as dialkyl-, alkoxy-, and haloboranes were also examined for the reduction of azides. This study revealed BHCl2·SMe2 to be the most suitable reagent for the reduction of azides. The chemoselectivity of this reagent was also studied by reducing n-hexyl azide in the presence of representative series of functional groups, including esters, halides, nitriles, and nitro groups. BHCl2·SMe2 reduces azides in the presence of all of the above functional groups as well as olefins. Taking advantage of the differences in reactivity of BHCl2·SMe2 and BH3·THF or BH3·SMe2, it is now possible to reduce selectively an azide in the presence of olefins or to hydroborate an olefin in the presence of azides by a judicious choice of the reagent.
- Salunkhe, Ashok M.,Veeraraghavan Ramachandran,Brown, Herbert C.
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- LIQUID PHASE CO-AMMONOLYSIS OF PHENOL AND CYCLOHEXANOL WITH PALLADIUM-ON-CARBON CATALYST
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In the presence of Pd/C catalyst, phenol and cyclohexanol are aminated simultaneously to aniline and cyclohexylamine by ammonolysis, while conversion of phenol or cyclohexanol alone is very poor.It is suggested that this amination is caused by hydrogen transfer between phenol and cyclohexanol.Ru/C, Rh/C, and Pt/C are ineffective for this co-amination.
- Hamada, Hideaki,Yamamoto, Makoto,Matsuzaki, Takehiko,Wakabayashi, Katsuhiko
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- Fe/Fe2O3@N-dopped Porous Carbon: A High-Performance Catalyst for Selective Hydrogenation of Nitro Compounds
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Herein, we designed and prepared a novel Fe/Fe2O3-based catalyst, in which a remarkable synergistic effect has been revealed between Fe and Fe2O3 encapsulated in N-doping porous carbon. The Fe-based catalysts were fabricated via pyrolysis a mixture of MIL-101(Fe) and melamine. The catalyst exhibits exceptionally high catalytic activity (TOFs up to 8898 h?1 which is about 100 times higher than the similar kinds of catalysts) and chemoselectivity for nitroarene reduction under mild conditions.
- Yun, Ruirui,Hong, Lirui,Ma, Wanjiao,Jia, Weiguo,Liu, Shoujie,Zheng, Baishu
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- Perbrominated 2-nitrotetraphenylporphyrins: Electrochemical and axial ligation properties
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A new series of perbrominated 2-nitro-5,10,15,20-tetraphenylporphyrins, H2TPPBrn(NO2) (n = 6 and 7) and their metal (CuII and ZnII) complexes have been synthesised and characterised. The presence of mixed electron withdrawing (bromo- and nitro-) substituents at the β-pyrrole positions induces interesting electrochemical and axial ligation properties. Perbrominated nitroporphyrins exhibit two successive one electron redox potentials with a positive shift of >100 mV relative to their corresponding octabromotetraphenylporphyrin (MTPPBr8) complexes. Axial ligation of various nitrogenous bases to ZnTPPBrn(NO2) complexes showed facile ligand binding with >50% enhancement in the equilibrium constants, Keq, relative to ZnTPPBr8. Surprisingly, MTPPBrn(NO2) complexes show similar axial ligation and electrochemical redox behaviour. The anodic shift in electrochemical redox potentials and enhanced Keq of MTPPBrn(NO2) complexes have been attributed to the increased electron deficiency of the porphyrin π-system.
- Bhyrappa, Puttaiah,Purushothaman, Bhavana
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- Amberlyst-15(H+)-NaBH4-LiCl: An effective reductor for oximes and hydrazones
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A simple and mild procedure reduces oximes and hydrazones on amberlyst 15(H+) support with LiCl-NaBH4 to the corresponding amines and hydrazines respectively in high yield and purity.
- Baruah, Bipul,Dutta, Manu P.,Boruah, Anima,Prajapati, Dipak,Sandhu, Jagir S.
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- Ligand-accelerated activation of strong C-H bonds of alkanes by a (salen)ruthenium(VI)-nitrido complex
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Kinetic and mechanistic studies on the intermolecular activation of strong C-H bonds of alkanes by a (salen)ruthenium(VI) nitride were performed. The initial, rate-limiting step, the hydrogen atom transfer (HAT) from the alkane to RuVI≡N, generates RuV=NH and RC.HCH 2R. The following steps involve N-rebound and desaturation. Copyright
- Man, Wai-Lun,Lam, William W. Y.,Kwong, Hoi-Ki,Yiu, Shek-Man,Lau, Tai-Chu
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- New Photolabile Amino Protecting Groups: Photogeneration of Amines from carbonyl Carbamates
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A novel class of photolabile amino protecting groups, based on carbonyl groups, is presented and their scope and versatility demonstrated by the photogeneration of free primary and secondary amines.
- Cameron, James F.,Willson, C. Grant,Frechet, Jean M. J.
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- Synthesis of 1,4-diaminocyclohexane in supercritical ammonia
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The amination of 1,4-cyclohexanediol in supercritical ammonia has been studied in a continuous fixed-bed reactor at 135 bar. An unsupported cobalt catalyst stabilized by 5 wt% Fe afforded the main reaction products 4-aminocyclohexanol and 1,4-diaminocyclohexane with a cumulative selectivity of 97% at 76% conversion. Excess of ammonia and short contact time favored the desired reactions. At low and high conversions the amination selectivity decreased due to the formation of dimers and oligomers and degradation products. Recycling of the unreacted diol and amino alcohol intermediate can provide an alternative economic process for the synthesis of 1,4-diaminocyclohexane.
- Fischer,Mallat,Baiker
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- Noble metal nanoparticles stabilized by hyper-cross-linked polystyrene as effective catalysts in hydrogenation of arenes
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This work is addressing the arenes’ hydrogenation—the processes of high importance for petrochemical, chemical and pharmaceutical industries. Noble metal (Pd, Pt, Ru) nanoparticles (NPs) stabilized in hyper-cross-linked polystyrene (HPS) were shown to be active and selective catalysts in hydrogenation of a wide range of arenes (monocyclic, condensed, substituted, etc.) in a batch mode. HPS effectively stabilized metal NPs during hydrogenation in different medium (water, organic solvents) and allowed multiple catalyst reuses.
- Bakhvalova, Elena S.,Bykov, Alexey V.,Demidenko, Galina N.,Kiwi-Minsker, Lioubov,Mikheev, Alexey V.,Nikoshvili, Linda Z.,Pinyukova, Arina O.,Sulman, Mikhail G.
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- Instantaneous SmI2/H2O/amine mediated reduction of nitroalkanes and α,β-unsaturated nitroalkenes
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A rapid method for efficient reduction of nitroalkanes and α,β-unsaturated nitroalkenes using SmI2/H2O/amine has been developed.
- Ankner, Tobias,Hilmersson, G?ran
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- Reductive amination of ketones: Novel one-step transfer hydrogenations in batch and continuous-flow mode
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Various ketones were efficiently transformed into the corresponding amines using ammonium formate in the presence of Zn dust or 10% Pd/C. The low-cost Zn dust method proved to be effective in amine formation from carbonyl groups at the benzylic side-chain position of aromatic systems, whereas 10% Pd/C was an efficient catalyst in the reductive aminations of carbonyl groups non-conjugated with any π-system. The 10% Pd/C-catalyzed reductions were performed more effectively in a continuous-flow X-Cube reactor than in the batch system.
- Falus, Péter,Boros, Zoltán,Hornyánszky, Gábor,Nagy, József,Darvas, Ferenc,ürge, László,Poppe, László
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- Essential role of heterocyclic structure of N-alkylated 2-pyrrolidone derivatives for recycling uranium from spent nuclear fuels
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In a simple and versatile reprocessing method for recycling U and Pu from spent nuclear fuels, cyclic amides like Nalkylated 2-pyrrolidone derivatives (NRPs) are exclusively employed. However, there has been no convincing rational to explain why such a heterocyclic structure is required. To answer this question, we employed N-cyclohexyl-2-pyrrolidone (NCP) and N-cyclohexylformamide (NCF) as cyclic and acyclic monodentate amides, and focused on the following 3 topics in this study; (1) structural chemistry of their uranyl dinitrato complexes, (2) precipitation behavior of UO22+ from HNO3(aq) by using these amides, and (3) their chemical stability in HNO3(aq) simulating the reprocessing conditions for spent nuclear fuels. Fundamental coordination chemistry of UO2(NO3)2(L)2 (L = NCP, NCF) was found to be common to both L, regardless of the presence or absence of the pyrrolidone ring. Furthermore, both L exhibit comparable capability in precipitation of UO22+ from HNO3(aq). The most critical difference between NCP and NCF was found in their chemical stability in HNO3(aq), where NCF was gradually decomposed through acid-catalyzed hydrolysis, while NCP remained intact for at least 4 h. In conclusion, the pyrrolidone ring of NRPs plays an important role to sterically protect the carbonyl C from nucleophilic hydrolysis which initiates the amide C(=O)N bond cleavage.
- Inoue, Tsubasa,Kazama, Hiroyuki,Takao, Koichiro,Tsushima, Satoru
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- Synthesis of polycyclic tertiary carbinamines by samarium diiodide mediated cyclizations of indolyl sulfinyl imines
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Samarium diiodide mediated cyclizations of N-acylated indole derivatives bearing sulfinyl imine moieties afforded polycyclic tertiary carbinamines with moderate to excellent diastereoselectivities. Lithium bromide and water turned out to be the best additives to achieve these transformations in good yields. Using enantiopure sulfinyl imines the outcome strongly depends on the reactivity of the indole moiety. Whereas with unactivated indole derivatives desulfinylation and formation of racemic products was observed, indoles bearing electron-withdrawing substituents at C-3 afforded the polycyclic products with intact N-sulfinyl groups and with excellent diastereoselectivity, finally allowing the preparation of enantiopure tertiary carbinamines. The mechanisms of these processes are discussed.
- Rao, Chintada Nageswara,Lentz, Dieter,Reissig, Hans-Ulrich
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- New and mild allyl carbamate deprotection method catalyzed by electrogenerated nickel complexes
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A Ni(II)-catalyzed electrochemical procedure for the simple and mild deprotection of allyl carbamates to the corresponding amines is described. The amines are obtained in yields of 40-99% and the method is compatible with several functional groups. Electrolyses are carried out in DMF or in THF in single-compartment cells in the presence of a consumable zinc anode. (C) 2000 Elsevier Science Ltd.
- Franco,Dunach
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- A ruthenium and palladium bimetallic system superior to a rhodium co-catalyst for TiO2-photocatalyzed ring hydrogenation of aniline to cyclohexylamine
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Cyclohexylamine (CHA) is used as an important raw material in chemical industries. Since the production of CHA requires a high temperature and excess amounts of hydrogen gas (H2) and ammonia, the development of a simple reaction operated under milder conditions using a safe compound is indispensable for achieving sustainable chemistry. A highly selective ring hydrogenation of aniline (AN) to CHA over a titanium(IV) oxide photocatalyst having a co-catalyst in water at room temperature, in which oxalic acid was used as the hydrogen source in place of H2, is described in this paper. Among TiO2 photocatalysts having co-catalysts, Rh-TiO2 showed high activity for CHA production, while Pd-TiO2 and Ru-TiO2 showed negligible activity. When a bimetallic photocatalyst, Ru/Pd-TiO2, was used, the yield was larger than that when Rh-TiO2 was used. Metal particles loaded on TiO2 were observed by using TEM, and electronic states of Ru and Pd were evaluated by using XPS. Interactions among metal, AN and CHA were investigated through adsorption experiments. Based on the results, active sites for AN hydrogenation are discussed.
- Araki, Sakae,Kominami, Hiroshi,Nakanishi, Kousuke,Tanaka, Atsuhiro
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- A magnetically separable gold catalyst for chemoselective reduction of nitro compounds
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Magnetically separable gold-nanoparticle catalyst was prepared, and it showed excellent activity for chemoselective reduction of nitroarenes with hydrosilanes. The Royal Society of Chemistry 2013.
- Park, Sungho,Lee, In Su,Park, Jaiwook
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- Reduction of O-acyl oximes with sodium borohydride/iodine system
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O-acyl derivatives of aldoximes and ketoximes are reduced in good yields to the corresponding amines with sodium borohydride-iodine system.
- Barbry,Champagne
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- O-(DIPHENYLPHOSPHINYL)HYDROXYLAMINE: A NEW REAGENT FOR ELECTROPHILIC C-AMINATION
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O-(Diphenylphosphinyl)hydroxylamine efficiently aminates a variety of stabilised carbanions and certain Grignard reagents.
- Colvin, Ernest W.,Kirby, Gordon W.,Wilson, Arthur C.
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- Low-temperature deacylation of N-monosubstituted amides
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(Chemical Equation Presented) The (PhO)3P-Cl2 reagent, prepared in situ by titrating a solution of triphenyl phosphite with chlorine, is used to convert N-monosubstituted amides into their corresponding amines. The reaction, if compared to other traditional methods, shows the advantage of very mild conditions and low temperature (-30°C→rt).
- Spaggiari, Alberto,Blaszczak, Larry C.,Prati, Fabio
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- Highly selective one-step hydrogenation of nitrobenzene to cyclohexylamine over the supported 10% Ni/carbon catalysts doped with 3‰ Rh
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The carbon supported 10% Ni catalysts doped with 3‰ Rh have been prepared by an impregnation method. These catalysts have been used to catalyze the one-step hydrogenation of nitrobenzene to cyclohexylamine. The results show that the 3‰ Rh-10% Ni/CSC (biocarbon) catalyst exhibits an excellent performance to achieve 100 mol% conversion of nitrobenzene and 91.6% selectivity of cyclohexylamine under reaction conditions of 3.5 MPa and 140 °C. The recycling tests reveal recyclable stability of 3‰ Rh-10% Ni/CSC. This catalyst is active for the hydrogenation of a series of electron-deficient nitrobenzenes. Some factors such as the type of carriers, the content of Ni and Rh, the type of metals and additives play important roles in controlling the selective hydrogenation.
- Lu, Xinhuan,Chen, Yang,Zhao, Zhenshuang,Deng, Hao,Zhou, Dan,Wei, Changcheng,Nie, Renfeng,Xia, Qinghua
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- Highly-dispersed and size-controlled ruthenium nanoparticles on carbon nanofibers: Preparation, characterization, and catalysis
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Facile synthesis of ruthenium nanoparticles supported on the carbon nanofibers (CNFs) is accomplished by thermal decomposition of Ru 3(CO)12; ruthenium species on the platelet-type CNF are dispersed homogeneously and selectively on the edge of the graphite layers with narrow size distributions and behaves as an excellent catalyst for arene hydrogenation. Copyright
- Motoyama, Yukihiro,Takasaki, Mikihiro,Higashi, Kenji,Yoon, Seong-Ho,Mochida, Isao,Nagashima, Hideo
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- Unprecedented efficient hydrogenation of arenes in biphasic liquid-liquid catalysis by re-usable aqueous colloidal suspensions of rhodium
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A reduced aqueous colloidal suspension of rhodium shows efficient activity for the catalytic hydrogenation of various benzene derivatives under biphasic conditions at room temperature and under atmospheric hydrogen pressure; the aqueous phase containing the Rh(0) particles can be re-used for further runs with a complete conservation of activity.
- Schulz, Juergen,Roucoux, Alain,Patin, Henri
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- Fe/Fe3C Encapsulated in N-Doped Carbon Tubes: A Recyclable Catalyst for Hydrogenation with High Selectivity
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Herein, a series of Fe-based catalysts have been designed and prepared by grinding a mixture of MIL-88d and melamine, and then the mixture was followed by pyrolysis. An unusual Fe/Fe3C-activated site is uniformly encapsulated in the N-doped carbon tubes obtained by pyrolysis of the film-like nanocrystals of MIL-88d. Experimental characterizations and theoretical calculations demonstrate that the surface N sites can effectively trap the nitrobenzene and aniline by their phenyl groups with the formation of three C-N bonds that made the catalyst exhibit excellent catalytic activity (turnover frequencies of ≤11268 h-1 calculated on the basis of nitrobenzene) and chemoselectivity for the reduction of nitro derivatives under facile conditions.
- Yun, Ruirui,Zhang, Shi,Ma, Wanjiao,Lv, Xiao,Liu, Shoujie,Sheng, Tian,Wang, Suna
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- Asymmetric synthesis of primary amines catalyzed by thermotolerant fungal reductive aminases
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Chiral primary amines are important intermediates in the synthesis of pharmaceutical compounds. Fungal reductive aminases (RedAms) are NADPH-dependent dehydrogenases that catalyse reductive amination of a range of ketones with short-chain primary amines supplied in an equimolar ratio to give corresponding secondary amines. Herein we describe structural and biochemical characterisation as well as synthetic applications of two RedAms fromNeosartoryaspp. (NfRedAm andNfisRedAm) that display a distinctive activity amongst fungal RedAms, namely a superior ability to use ammonia as the amine partner. Using these enzymes, we demonstrate the synthesis of a broad range of primary amines, with conversions up to >97% and excellent enantiomeric excess. Temperature dependent studies showed that these homologues also possess greater thermal stability compared to other enzymes within this family. Their synthetic applicability is further demonstrated by the production of several primary and secondary amines with turnover numbers (TN) up to 14 000 as well as continous flow reactions, obtaining chiral amines such as (R)-2-aminohexane in space time yields up to 8.1 g L?1h?1. The remarkable features ofNfRedAmand NfisRedAm highlight their potential for wider synthetic application as well as expanding the biocatalytic toolbox available for chiral amine synthesis.
- Cosgrove, Sebastian C.,Grogan, Gideon,Mangas-Sanchez, Juan,Marshall, James R.,Palmer, Ryan B.,Ramsden, Jeremy I.,Sharma, Mahima,Thorpe, Thomas W.,Turner, Nicholas J.
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- ELECTROCATALYTIC HYDROGENATION OF ORGANIC COMPOUNDS ON DEVARDA COPPER AND RANEY NICKEL ELECTRODES IN BASIC MEDIA
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Using Devarda copper and Raney nickel electrodes, nitrobenzene, nitrocyclohexane, p-nitroacetophenone, N-methyl-p-anisaldehyde imine, benzophenone, and phenanthrene have been electrocatalytically hydrogenated with high chemical and current efficiency.
- Belot, Gerard,Desjardins, Sylvie,Lessard, Jean
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- Synthesis of aziridinosteroids
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11α,12α-aziridinosteroids (2a, b, c) were prepared from 5β-H-11-pregnene-3, 20-dione (1) using different iminophenyliodinanes and cloramine aziridination reagents.
- Di Chenna,Dauban,Ghini,Burton,Dodd
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- Post-functionalized iridium-Zr-MOF as a promising recyclable catalyst for the hydrogenation of aromatics
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The multifunctional heterogeneous catalyst iridium-Zr-based MOF is able to effectively catalyze the hydrogenation of aromatic compounds in high yields under mild conditions. The catalyst was found to be highly active and reusable, giving similar reactivity and selectivity after at least five catalytic uses. This journal is the Partner Organisations 2014.
- Rasero-Almansa, Antonia M.,Corma, Avelino,Iglesias, Marta,Sanchez, Felix
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- A simple and reproducible method for the synthesis of silica-supported rhodium nanoparticles and their investigation in the hydrogenation of aromatic compounds
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Colloidal suspensions of rhodium nanoparticles have been easily prepared in aqueous solution by chemical reduction of the precursor RhCl 3·3H2O in the presence of the surfactant N,N-dimethyl-N-cetyl-N-(2-hydroxyethyl)ammonium chloride (HEA16Cl) and further used to immobilize rhodium nanoparticles on silica by simple impregnation. The obtained silica-supported rhodium nanoparticles have been investigated by adapted characterization methods such as transmission electron microscopy and X-ray photoelectron spectroscopy. A particle size increase from 2.4 to 5 nm after the silica immobilization step and total elimination of the surfactant has been observed. This "heterogeneous" catalyst displayed good activities for the hydrogenation of mono-, di- alkylsubstituted and/or functionalized aromatic derivatives in water under atmospheric hydrogen pressure and at room temperature. In all cases, the catalyst could be recovered several times after a simple decantation or filtration and reused without any significant loss in catalytic activity. This supported catalyst has also been tested under higher hydrogen pressure giving rise to TOFs reaching 6430 h -1 at 30 bar and in terms of catalytic lifetime 30 000 TTO in 8.5 h for pure anisole hydrogenation at 40 bar. the Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2006.
- Mevellec, Vincent,Nowicki, Audrey,Roucoux, Alain,Dujardin, Christophe,Granger, Pascal,Payen, Edmond,Philippot, Karine
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- VERSATILE POLYMER-BOUND RHODIUM CATALYSTS. FACILE HYDROGENATION OF AROMATIC COMPOUNDS IN THE LIQUID PHASE
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Immobilized complexes prepared from 2 (nbd=norbornadiene) and phosphinated polydiacetylene or silica are efficient catalysts for the hydrogenation of arenes under mild conditions.However, the homologous catalyst supported on a phosphinated polystyrene is not active.
- Okano, Tamon,Tsukiyama, Katsunori,Konishi, Hisatoshi,Kiji, Jitsuo
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- Green Synthesis of Rhodium Nanoparticles that are Catalytically Active in Benzene Hydrogenation and 1-Hexene Hydroformylation
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Rhodium nanoparticles (Rh NPs) were prepared according to a green method based on the reduction of (acetylacetonato)dicarbonylrhodium(I), Rh(acac)(CO)2, in water at 80 °C. The nanoparticles, which were obtained without the addition of a reducing agent, were stabilized by polyvinylpyrrolidone (PVP) or polyvinyl alcohol (PVA) polymers and characterized by TEM (transmission electron microscopy), XPS (X-ray photoelectron spectroscopy), and XRD (X-ray powder diffraction) methods. The excellent catalytic activity of these Rh NPs was evidenced in the hydrogenation of benzene to cyclohexane. In the presence of PPh3, Rh NPs formed a highly active system in the hydroformylation of 1-hexene. In this system, they acted as a source of soluble rhodium species. Rh NPs were also synthesized in water using rhodium(II) acetate, Rh2(OAc)4, and rhodium(III) chloride, RhCl3, as rhodium sources, and their catalytic activity was compared with that of the rhodium precursors.
- Alsalahi, Waleed,Tylus, Wlodzimierz,Trzeciak, Anna M.
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- N,N-Chelate nickel(II) complexes bearing Schiff base ligands as efficient hydrogenation catalysts for amine synthesis
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Five N, N-chelate nickel (II) complexes bearing N-(2-pyridinylmethylene)-benzylamine ligands with different substituent groups were synthesized in good yields. The nickel complexes exhibited prominent catalytic efficiency toward amine synthesis from nitro compounds by using NaBH4 or H2 as hydrogen source through two catalytic systems. Various amines with different substituents were obtained in moderate to excellent yields. All substrates with electron-donating and electron-withdrawing properties were tolerated in the two reduction systems. Given the efficient catalytic activity, broad substance scope, and mild reduction conditions, the nickel catalysts have potential applications in industrial production.
- Xu, Mengyin,Wang, Yang,Zhou, Yifeng,Yao, Zi-Jian
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- MATERIALS COMPRISING CARBON-EMBEDDED COBALT NANOPARTICLES, PROCESSES FOR THEIR MANUFACTURE, AND USE AS HETEROGENEOUS CATALYSTS
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The present invention relates to catalytically active material, comprising grains of non-graphitizing carbon with cobalt nanoparticles dispersed therein, wherein dP, the average diameter of cobalt nanoparticles in the non-graphitizing carbon grains, is in the range of 1 nm to 20 nm, D, the average distance between cobalt nanoparticles in the non-graphitizing carbon grains, is in the range of 2 nm to 150 nm, and ω, the combined total mass fraction of metal in the non-graphitizing carbon grains, is in the range of 30 wt% to 70 wt% of the total mass of the non-graphitizing carbon grains, and wherein dP, D and ω conform to the following relation: 4.5 dP / ω > D ≥ 0.25 dP / ω. The present invention, further, relates to a process for the manufacture of material according to the invention, as well as its use as a catalyst.
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Page/Page column 17; 19-20
(2021/03/13)
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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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- Chemoselective and Tandem Reduction of Arenes Using a Metal–Organic Framework-Supported Single-Site Cobalt Catalyst
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The development of heterogeneous, chemoselective, and tandem catalytic systems using abundant metals is vital for the sustainable synthesis of fine and commodity chemicals. We report a robust and recyclable single-site cobalt-hydride catalyst based on a porous aluminum metal–organic framework (DUT-5 MOF) for chemoselective hydrogenation of arenes. The DUT-5 node-supported cobalt(II) hydride (DUT-5-CoH) is a versatile solid catalyst for chemoselective hydrogenation of a range of nonpolar and polar arenes, including heteroarenes such as pyridines, quinolines, isoquinolines, indoles, and furans to afford cycloalkanes and saturated heterocycles in excellent yields. DUT-5-CoH exhibited excellent functional group tolerance and could be reusable at least five times without decreased activity. The same MOF-Co catalyst was also efficient for tandem hydrogenation–hydrodeoxygenation of aryl carbonyl compounds, including biomass-derived platform molecules such as furfural and hydroxymethylfurfural to cycloalkanes. In the case of hydrogenation of cumene, our spectroscopic, kinetic, and density functional theory (DFT) studies suggest the insertion of a trisubstituted alkene intermediate into the Co–H bond occurring in the turnover limiting step. Our work highlights the potential of MOF-supported single-site base–metal catalysts for sustainable and environment-friendly industrial production of chemicals and biofuels.
- Akhtar, Naved,Begum, Wahida,Chauhan, Manav,Manna, Kuntal,Newar, Rajashree,Rawat, Manhar Singh
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supporting information
(2022/01/19)
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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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- Self-regulated catalysis for the selective synthesis of primary amines from carbonyl compounds
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Most current processes for the general synthesis of primary amines by reductive amination are performed with enormously excessive amounts of hazardous ammonia. It remains unclear how catalysts should be designed to regulate amination reaction dynamics at a low ammonia-to-substrate ratio for the quantitative synthesis of primary amines from the corresponding carbonyl compounds. Herein we show a facile control of the reaction selectivity in the layered boron nitride supported ruthenium catalyzed reductive amination reaction. Specifically, locating ruthenium to the edge surface of layered boron nitride leads to an increased hydrogenation activity owing to the enhanced interfacial electronic effects between ruthenium and the edge surface of boron nitride. This enables self-accelerated reductive amination reactions which quantitatively synthesize structurally diverse primary amines by reductive amination of carbonyl compounds with twofold ammonia. This journal is
- Fan, Xiaomeng,Gao, Jin,Gao, Mingxia,Jia, Xiuquan,Ma, Jiping,Xu, Jie
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supporting information
p. 7115 - 7121
(2021/09/28)
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- Generation of Oxidoreductases with Dual Alcohol Dehydrogenase and Amine Dehydrogenase Activity
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The l-lysine-?-dehydrogenase (LysEDH) from Geobacillus stearothermophilus naturally catalyzes the oxidative deamination of the ?-amino group of l-lysine. We previously engineered this enzyme to create amine dehydrogenase (AmDH) variants that possess a new hydrophobic cavity in their active site such that aromatic ketones can bind and be converted into α-chiral amines with excellent enantioselectivity. We also recently observed that LysEDH was capable of reducing aromatic aldehydes into primary alcohols. Herein, we harnessed the promiscuous alcohol dehydrogenase (ADH) activity of LysEDH to create new variants that exhibited enhanced catalytic activity for the reduction of substituted benzaldehydes and arylaliphatic aldehydes to primary alcohols. Notably, these novel engineered dehydrogenases also catalyzed the reductive amination of a variety of aldehydes and ketones with excellent enantioselectivity, thus exhibiting a dual AmDH/ADH activity. We envisioned that the catalytic bi-functionality of these enzymes could be applied for the direct conversion of alcohols into amines. As a proof-of-principle, we performed an unprecedented one-pot “hydrogen-borrowing” cascade to convert benzyl alcohol to benzylamine using a single enzyme. Conducting the same biocatalytic cascade in the presence of cofactor recycling enzymes (i.e., NADH-oxidase and formate dehydrogenase) increased the reaction yields. In summary, this work provides the first examples of enzymes showing “alcohol aminase” activity.
- Tseliou, Vasilis,Schilder, Don,Masman, Marcelo F.,Knaus, Tanja,Mutti, Francesco G.
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supporting information
p. 3315 - 3325
(2020/12/11)
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- Biochemical and Structural Characterization of an (R)-Selective Transaminase in the Asymmetric Synthesis of Chiral Hydroxy Amines
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An (R)-selective transaminase RbTA with excellent stereoselectivity (>99% ee) in the asymmetric amination of hydroxy ketones was identified. Biochemical characterization showed that RbTA exhibited the highest activity toward 4-hydroxy-2-butanone among reported enzymes, and that it has broad substrate specificity, including for aliphatic, aromatic, and alicyclic ketones. Crystallization of RbTA were performed, as were molecular docking and mutagenesis studies. Residue Tyr125 plays a key role in substrate recognition by forming a hydrogen bond with hydroxy ketone. The applicability of the enzyme was determined in preparative-scale synthesis of (R)-3-amino-1-butanol, demonstrating the potential of RbTA as a green biocatalyst for production of value-added chiral hydroxy amines. This study provides an efficient tool for enzymatic synthesis of chiral hydroxy amines, as well as structural insight into substrate recognition by transaminases in the asymmetric amination of hydroxy ketones. (Figure presented.).
- Li, Fulong,Liang, Youxiang,Wei, Yuwen,Zheng, Yukun,Du, Yan,Yu, Huimin
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supporting information
p. 4582 - 4589
(2021/08/07)
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- Synthesis of Chiral Amines via a Bi-Enzymatic Cascade Using an Ene-Reductase and Amine Dehydrogenase
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Access to chiral amines with more than one stereocentre remains challenging, although an increasing number of methods are emerging. Here we developed a proof-of-concept bi-enzymatic cascade, consisting of an ene reductase and amine dehydrogenase (AmDH), to afford chiral diastereomerically enriched amines in one pot. The asymmetric reduction of unsaturated ketones and aldehydes by ene reductases from the Old Yellow Enzyme family (OYE) was adapted to reaction conditions for the reductive amination by amine dehydrogenases. By studying the substrate profiles of both reported biocatalysts, thirteen unsaturated carbonyl substrates were assayed against the best duo OYE/AmDH. Low (5 %) to high (97 %) conversion rates were obtained with enantiomeric and diastereomeric excess of up to 99 %. We expect our established bi-enzymatic cascade to allow access to chiral amines with both high enantiomeric and diastereomeric excess from varying alkene substrates depending on the combination of enzymes.
- Fossey-Jouenne, Aurélie,Jongkind, Ewald P. J.,Mayol, Ombeline,Paul, Caroline E.,Vergne-Vaxelaire, Carine,Zaparucha, Anne
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- Palladium supported on magnesium hydroxyl fluoride: An effective acid catalyst for the hydrogenation of imines and N-heterocycles
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Palladium catalysts supported on acidic fluorinated magnesium hydroxide Pd/MgF2-x(OH)x were prepared through precipitation or impregnation methods. Applications to the hydrogenation of various aldimines and ketimines resulted in good catalytic activities at mild temperatures using one atmosphere of hydrogen. Quinolines, pyridines and other N-heterocycles were successfully hydrogenated at higher temperature and hydrogen pressure using low palladium loadings and without the use of any acid additive. Such reactivity trend confirmed the positive effect of the Br?nsted and Lewis acid sites from the fluorinated magnesium hydroxide support resulting in the effective pre-activation of N-heterocycle substrates and therefore in the good catalytic activity of the palladium nanoparticles during the hydrogenations. As demonstrated in the hydrogenation of imines, the catalyst was recycled up to 10 times without either loss of activity or palladium leaching. This journal is
- Agbossou-Niedercorn, Francine,Corre, Yann,Dongare, Mohan K.,Kemnitz, Erhard,Kokane, Reshma,Michon, Christophe,Umbarkar, Shubhangi B.
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supporting information
p. 19572 - 19583
(2021/11/04)
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- PRODUCTION METHOD OF CYCLIC COMPOUND
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PROBLEM TO BE SOLVED: To provide an industrially simple production method of a cyclic compound. SOLUTION: A production method of a cyclic compound includes a step to obtain a reduced form (B) by reducing an unsaturated bond in a ring structure of an aromatic compound (A) by means of catalytic hydrogenation of the aromatic compound (A) or its salt using palladium carbon as a catalyst under a normal pressure, in which the aromatic compound (A) has one or more ring structures selected from a group consisting of a five membered-ring, a six membered-ring, and a condensed ring of the five membered-ring or the six membered-ring with another six membered-ring, a hetero atom can be included in the ring structure, and the aromatic compound (A) can have one or two side chains bonded to the ring structure and does not have any carbon-carbon triple bond in the side chain. SELECTED DRAWING: None COPYRIGHT: (C)2021,JPOandINPIT
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Paragraph 0057; 0060; 0062; 0065
(2021/05/05)
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- Method for preparing amine through catalytic reduction of nitro compound by cyclic (alkyl) (amino) carbene chromium complex
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The cyclic (alkyl) (amino) carbene chromium complex is prepared from corresponding ligand salt, alkali and CrCl3 and used for catalyzing pinacol borane to reduce nitro compounds in an ether solvent under mild conditions to generate corresponding amine. The method for preparing amine has the advantages of cheap and accessible raw materials, mild reaction conditions, wide substrate application range, high selectivity and the like, and is simple to operate.
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Paragraph 0015
(2021/04/17)
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- Indirect reduction of CO2and recycling of polymers by manganese-catalyzed transfer hydrogenation of amides, carbamates, urea derivatives, and polyurethanes
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The reduction of polar bonds, in particular carbonyl groups, is of fundamental importance in organic chemistry and biology. Herein, we report a manganese pincer complex as a versatile catalyst for the transfer hydrogenation of amides, carbamates, urea derivatives, and even polyurethanes leading to the corresponding alcohols, amines, and methanol as products. Since these compound classes can be prepared using CO2as a C1 building block the reported reaction represents an approach to the indirect reduction of CO2. Notably, these are the first examples on the reduction of carbamates and urea derivatives as well as on the C-N bond cleavage in amides by transfer hydrogenation. The general applicability of this methodology is highlighted by the successful reduction of 12 urea derivatives, 26 carbamates and 11 amides. The corresponding amines, alcohols and methanol were obtained in good to excellent yields up to 97%. Furthermore, polyurethanes were successfully converted which represents a viable strategy towards a circular economy. Based on control experiments and the observed intermediates a feasible mechanism is proposed.
- Liu, Xin,Werner, Thomas
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p. 10590 - 10597
(2021/08/20)
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- RhNPs supported onN-functionalized mesoporous silica: effect on catalyst stabilization and catalytic activity
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Amine and nicotinamide groups grafted on ordered mesoporous silica (OMS) were investigated as stabilizers for RhNPs used as catalysts in the hydrogenation of several substrates, including carbonyl and aryl groups. Supported RhNPs on functionalized OMS were prepared by controlled decomposition of an organometallic precursor of rhodium under dihydrogen pressure. The resulting materials were characterized thoroughly by spectroscopic and physical techniques (FTIR, TGA, BET, SEM, TEM, EDX, XPS) to confirm the formation of spherical rhodium nanoparticles with a narrow size distribution supported on the silica surface. The use of nicotinamide functionalized OMS as a support afforded small RhNPs (2.3 ± 0.3 nm), and their size and shape were maintained after the catalyzed acetophenone hydrogenation. In contrast, amine-functionalized OMS formed RhNP aggregates after the catalytic reaction. The supported RhNPs could selectively reduce alkenyl, carbonyl, aryl and heteroaryl groups and were active in the reductive amination of phenol and morpholine, using a low concentration of the precious metal (0.07-0.18 mol%).
- Pulido-Díaz, Israel T.,Serrano-Maldonado, Alejandro,López-Suárez, Carlos César,Méndez-Ocampo, Pedro A.,Portales-Martínez, Benjamín,Gutiérrez-Alejandre, Aída,Salas-Martin, Karla P.,Guerrero-Ríos, Itzel
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p. 3289 - 3298
(2021/03/16)
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- Development and Application of Efficient Ag-based Hydrogenation Catalysts Prepared from Rice Husk Waste
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The development of strategies for the sustainable management and valorization of agricultural waste is of outmost importance. With this in mind, we report the use of rice husk (RH) as feedstock for the preparation of heterogeneous catalysts for hydrogenation reactions. The catalysts were prepared by impregnating the milled RH with a silver nitrate solution followed by carbothermal reduction. The composition and morphology of the prepared catalysts were fully assessed by IR, AAS, ICP-MS, XPS, XRD and STEM techniques. This novel bio-genic silver-based catalysts showed excellent activity and remarkable selectivity in the hydrogenation of nitro groups in both aromatic and aliphatic substrates, even in the presence of reactive functionalities like halogens, carbonyls, borate esters or nitriles. Recycling experiments showed that the catalysts can be easily recovered and reused multiple times without significant drop in performance and without requiring re-activation.
- Unglaube, Felix,Kreyenschulte, Carsten Robert,Mejía, Esteban
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p. 2583 - 2591
(2021/04/09)
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- Rhodium-terpyridine Catalyzed Transfer Hydrogenation of Aromatic Nitro Compounds in Water
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A rhodium terpyridine complex catalyzed transfer hydrogenation of nitroarenes to anilines with i-PrOH as hydrogen source and water as solvent has been developed. The catalytic system can work at a substrate/catalyst (S/C) ratio of 2000, with a turnover frequency (TOF) up to 3360 h?1, which represents one of the most active catalytic transfer hydrogenation systems for nitroarene reduction. The catalytic system is operationally simple and the protocol could be scaled up to 20 gram scale. The water-soluble catalyst bearing a carboxyl group could be recycled 15 times without significant loss of activity.
- Liu, Yuxuan,Miao, Wang,Tang, Weijun,Xue, Dong,Xiao, Jianliang,Wang, Chao,Li, Changzhi
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supporting information
p. 1725 - 1729
(2021/06/01)
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- Synthesis, Structure, and Catalytic Hydrogenation Activity of [NO]-Chelate Half-Sandwich Iridium Complexes with Schiff Base Ligands
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A series of N,O-coordinate iridium(III) complexes with a half-sandwich motif bearing Schiff base ligands for catalytic hydrogenation of nitro and carbonyl substrates have been synthesized. All iridium complexes showed efficient catalytic activity for the hydrogenation of ketones, aldehydes, and nitro-containing compounds using clean H2 as reducing reagent. The iridium catalyst displayed the highest TON values of 960 and 950 in the hydrogenation of carbonyl and nitro substrates, respectively. Various types of substrates with different substituted groups afforded corresponding products in excellent yields. All N,O-coordinate iridium(III) complexes 1-4 were well characterized by IR, NMR, HRMS, and elemental analysis. The molecular structure of complex 1 was further characterized by single-crystal X-ray determination.
- Lv, Wen-Rui,Li, Rong-Jian,Liu, Zhen-Jiang,Jin, Yan,Yao, Zi-Jian
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p. 8181 - 8188
(2021/05/26)
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- Highly Efficient and Chemoselective Hydrogenation of Nitro Compounds into Amines by Nitrogen-Doped Porous Carbon-Supported Co/Ni Bimetallic Nanoparticles
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A novel Co/Ni bimetallic nanoparticle supported by nitrogen-doped porous carbon (NPC), Co5/Ni@NPC-700, exhibits high conversion, chemoselectivity, and recyclability in the hydrogenation of 16 different nitro compounds into desired amines with hydrazine hydrate under mild conditions. The synergistic effects of Co/Ni bimetal nanoparticles and the NPC-supported porous honeycomb structure with more accessible active sites may be responsible for the high catalytic hydrogenation performance.
- Shen, Zeyu,Hong, Lirui,Zheng, Baishu,Wang, Guanyu,Zhang, Beibei,Wang, Zhaoxu,Zhan, Feiyang,Shen, Shaohua,Yun, Ruirui
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supporting information
p. 16834 - 16839
(2021/11/17)
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- A Pod-like Core-Shell Catalyst with High Reduction Performance Under Mild Conditions
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Recent years, tubular structure as the carrier loading nanoparticles has been reported more and more frequently which is synthesized by pyrolysis polyhedral MOFs. However, the construct mechanism has not been referred. Herein, a tubular structure has been designed by calcining modified ZIF-8 under different temperature to reveal the formation process of tubular carbon from the polyhedron. As a result, a pod-like core-shell catalyst of Fe/Fe3C-900 has been obtained and exhibits a high activity and excellent substituent tolerance for the reduction of nitro groups under mild conditions.
- Du, Liting,He, Lei,Li, Tuanhui,Luo, Shizhou,Xu, Fagong,Yun, Ruirui,Zhan, Feiyang,Zhang, Beibei,Zheng, Baishu
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- Catalytic Hydrogenation of Urea Derivatives and Polyureas
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We present herein the catalytic hydrogenation of various urea derivatives to amines and methanol. The reaction is catalyzed by a ruthenium or an iridium Macho pincer complex and produces amine and methanol in very good to excellent yields. Moreover, we also expand this concept to demonstrate the first example of the hydrogenative depolymerization of polyureas to produce diamines and methanol in moderate yields.
- Kumar, Amit,Luk, James
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supporting information
p. 4546 - 4550
(2021/08/30)
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- A convenient Hofmann reaction of carboxamides and cyclic imides mediated by trihaloisocyanuric acids
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A simple, efficient and pot-economic approach in a single vessel has been developed for conversion of aromatic and aliphatic carboxamides into primary amines with one fewer carbom atom (Hofmann reaction) in 38–89 % yield by reacting with trichloro- or tribromoisocyanuric acid and sodium hydroxide in aqueous acetonitrile. Under the same reaction conditions, cyclic imides gave amino acids (69–83 %). The role of the trihaloisocyanuric acids is the in situ generation of N-haloamides, key-intermediates for the Hofmann reaction. The scalability of the methodology was demonstrated by a multigram-scale transformation of phthalimide into anthranilic acid in 77 % yield.
- Bastos, Gustavo A.,de Mattos, Marcio C.S.
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- Ambient-Temperature Synthesis of Primary Amines via Reductive Amination of Carbonyl Compounds
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Efficient synthesis of primary amines via low-temperature reductive amination of carbonyl compounds using NH3 and H2 as the nitrogen and hydrogen resources is highly desired and challenging in the chemistry community. Herein, we employed naturally occurring phytic acid as a renewable precursor to fabricate titanium phosphate (TiP)-supported Ru nanocatalysts with different reduction degrees of RuO2 (Ru/TiP-x, x represents the reduction temperature) by combining ball milling and molten-salt processes. Very interestingly, the obtained Ru/TiP-100 had good catalytic performance for the reductive amination of carbonyl compounds at ambient temperature, resulting from the synergistic cooperation of the support (TiP) and the Ru/RuO2 with a suitable proportion of Ru0 (52%). Various carbonyl compounds could be efficiently converted into the corresponding primary amines with high yields. More importantly, the conversion of other substrates with reducible groups could also be achieved at ambient temperature. Detailed investigations indicated that the partially reduced Ru and the support (TiP) were indispensable. The high activity and selectivity of Ru/TiP-100 catalyst originates from the relatively high acidity and the suitable electron density of metallic Ru0.
- Xie, Chao,Song, Jinliang,Hua, Manli,Hu, Yue,Huang, Xin,Wu, Haoran,Yang, Guanying,Han, Buxing
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p. 7763 - 7772
(2020/08/21)
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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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p. 1884 - 1893
(2020/04/07)
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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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- Iridium nanoparticles deposited on hypercrosslinked polystyrene: synthesis and application in the hydrogenation of aromatic compounds
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A novel method for the incorporation of iridium nanoparticles into a hypercrosslinked polystyrene matrix is developed using supercritical CO2 as reaction medium. The composite has regularly distributed iridium nanoparticles with monomodal size of ca 5?nm. The catalyst shows high activity in the hydrogenation of benzene and can be recycled ten times without any decrease in productivity. The catalyst gave a full conversion in the hydrogenation of toluene to methylcyclohexane and fluoro- and chlorobenzene to cyclohexane.
- Lyubimov, Sergey E.,Sokolovskaya, Marina V.,Korlyukov, Alexander A.,Parenago, Oleg P.,Davankov, Vadim A.
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p. 1283 - 1287
(2020/02/15)
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- Ru/g-C3N4as an efficient catalyst for selective hydrogenation of aromatic diamines to alicyclic diamines
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A series of Ru/g-C3N4materials with highly dispersed Ru were firstly prepared by an ultrasonic impregnation method using carbon nitride as a support. The catalysts were characterized by various techniques including BET and elemental analysis, ICP-AES, XPS, XRD, CO2-TPD and TEM. The results demonstrated that Ru/g-C3N4materials with a mesoporous structure and highly dispersed Ru were successfully prepared. The chemo-selective hydrogenation ofp-phenylenediamine (PPDA) to 1,4-cyclohexanediamine (CHDA) over Ru/g-C3N4as a model reaction was investigated in detail. PPDA conversion of 100% with a CHDA selectivity of more than 86% could be achieved under mild conditions. It can be inferred that the carbon nitride support possessed abundant basic sites and the Ru/g-C3N4-Tcatalysts provided suitable basicity for the aromatic ring hydrogenation. Compared to the N-free Ru/C catalyst, the involvement of nitrogen species in Ru/g-C3N4remarkably improved the catalytic performance. In addition, the recyclability of the catalyst demonstrated that the aggregation of Ru nanoparticles was responsible for the decrease of the catalytic activity. Furthermore, this strategy also could be expanded to the selective hydrogenation of other aromatic diamines to alicyclic diamines.
- Cao, Junya,Cao, Yan,Chen, Jiaqiang,Han, Fenggang,He, Peng,Huang, Xiaoyu,Li, Huiquan,Wang, Liguo,Yang, Huanhuan
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p. 16515 - 16525
(2020/05/13)
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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 0037
(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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- Selective hydrogenation of lignin-derived compounds under mild conditions
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A key challenge in the production of lignin-derived chemicals is to reduce the energy intensive processes used in their production. Here, we show that well-defined Rh nanoparticles dispersed in sub-micrometer size carbon hollow spheres, are able to hydrogenate lignin derived products under mild conditions (30 °C, 5 bar H2), in water. The optimum catalyst exhibits excellent selectivity and activity in the conversion of phenol to cyclohexanol and other related substrates including aryl ethers.
- Chen, Lu,Van Muyden, Antoine P.,Cui, Xinjiang,Laurenczy, Gabor,Dyson, Paul J.
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p. 3069 - 3073
(2020/06/17)
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- General and selective synthesis of primary amines using Ni-based homogeneous catalysts
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The development of base metal catalysts for industrially relevant amination and hydrogenation reactions by applying abundant and atom economical reagents continues to be important for the cost-effective and sustainable synthesis of amines which represent highly essential chemicals. In particular, the synthesis of primary amines is of central importance because these compounds serve as key precursors and central intermediates to produce value-added fine and bulk chemicals as well as pharmaceuticals, agrochemicals and materials. Here we report a Ni-triphos complex as the first Ni-based homogeneous catalyst for both reductive amination of carbonyl compounds with ammonia and hydrogenation of nitroarenes to prepare all kinds of primary amines. Remarkably, this Ni-complex enabled the synthesis of functionalized and structurally diverse benzylic, heterocyclic and aliphatic linear and branched primary amines as well as aromatic primary amines starting from inexpensive and easily accessible carbonyl compounds (aldehydes and ketones) and nitroarenes using ammonia and molecular hydrogen. This Ni-catalyzed reductive amination methodology has been applied for the amination of more complex pharmaceuticals and steroid derivatives. Detailed DFT computations have been performed for the Ni-triphos based reductive amination reaction, and they revealed that the overall reaction has an inner-sphere mechanism with H2metathesis as the rate-determining step.
- Beller, Matthias,Chandrashekhar, Vishwas G.,Jagadeesh, Rajenahally V.,Jiao, Haijun,Murugesan, Kathiravan,Wei, Zhihong
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p. 4332 - 4339
(2020/05/18)
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- Preparation method of cyclohexanone-oxime
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The invention relates to a preparation method of cyclohexanone-oxime, which mainly comprises the following steps: (1) oxidizing cyclohexane and molecular oxygen under the action of a solid catalyst, carrying out one-step reaction to generate KA oil, and performing separation to obtain the KA oil; (2) directly aminating the KA oil with ammonia and hydrogen under the action of a solid catalyst to generate cyclohexylamine and a small amount of byproduct-A, and performing separation to obtain cyclohexylamine; (3) carrying out partial oxidation on cyclohexylamine and molecular oxygen under the action of a solid catalyst to obtain an oxidation product mainly composed of cyclohexanone-oxime, a small amount of byproduct-B and cyclohexylamine which may not be completely converted; and (4) aminatingthe oxidation product, namely, directly carrying out amination reaction on the oxidation product obtained in the step (3), ammonia and hydrogen under the action of a solid catalyst without separation, converting the byproduct-B into cyclohexylamine, and performing separation to obtain cyclohexanone-oxime. The method is short in technological process, small in occupied area and investment, low incost and environmentally friendly.
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Paragraph 0036
(2020/06/05)
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- Facile synthesis of controllable graphene-co-shelled reusable Ni/NiO nanoparticles and their application in the synthesis of amines under mild conditions
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The primary objective of many researchers in chemical synthesis is the development of recyclable and easily accessible catalysts. These catalysts should preferably be made from Earth-abundant metals and have the ability to be utilised in the synthesis of pharmaceutically important compounds. Amines are classified as privileged compounds, and are used extensively in the fine and bulk chemical industries, as well as in pharmaceutical and materials research. In many laboratories and in industry, transition metal catalysed reductive amination of carbonyl compounds is performed using predominantly ammonia and H2. However, these reactions usually require precious metal-based catalysts or RANEY nickel, and require harsh reaction conditions and yield low selectivity for the desired products. Herein, we describe a simple and environmentally friendly method for the preparation of thin graphene spheres that encapsulate uniform Ni/NiO nanoalloy catalysts (Ni/NiO?C) using nickel citrate as the precursor. The resulting catalysts are stable and reusable and were successfully used for the synthesis of primary, secondary, tertiary, and N-methylamines (more than 62 examples). The reaction couples easily accessible carbonyl compounds (aldehydes and ketones) with ammonia, amines, and H2 under very mild industrially viable and scalable conditions (80 °C and 1 MPa H2 pressure, 4 h), offering cost-effective access to numerous functionalized, structurally diverse linear and branched benzylic, heterocyclic, and aliphatic amines including drugs and steroid derivatives. We have also demonstrated the scale-up of the heterogeneous amination protocol to gram-scale synthesis. Furthermore, the catalyst can be immobilized on a magnetic stirring bar and be conveniently recycled up to five times without any significant loss of catalytic activity and selectivity for the product.
- Cui, Zhibing,Liu, Jianguo,Liu, Qiying,Ma, Longlong,Singh, Thishana,Wang, Chenguang,Wang, Nan,Zhu, Yuting
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supporting information
p. 7387 - 7397
(2020/11/19)
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- Highly efficient one-pot multi-directional selective hydrogenation and N-alkylation catalyzed by Ru/LDH under mild conditions
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Atomic economy, non-toxicity, harmlessness and multidirectional selectivity advocated by green chemistry have increasingly become a hot and difficult research topic. Herein, we present a highly efficient, one-pot tandem and easy-to-operate method through which we could directly produce a broad range of multi-directional selective hydrogenated amines or N-alkyl aliphatic amines using aromatic nitro compounds as raw materials. Ru/LDH with characteristics of layered mesoporous structure, well dispersed small Ru nanoparticles and LDH stabilization to the Ru NPs was employed as the catalyst. It is remarkable that multi-directional superb chemoselectivity to aromatic amines, alicyclic amines as well as N-alkyl aliphatic amines could be achieved with excellent catalytic activity and recyclability by tuning reaction conditions over 5wt%Ru/LDH-2. Additionally, this catalytic system also exhibited attractive activity and multi-directional chemoselectivity in the hydrogenation of quinoline and its derivatives with solvents of different polarity. Chemoselectivity to 5,6,7,8-tetrahydroquinoline derivatives could reach as high as 95.6 %.
- Zhang, Sishi,Xu, Jie,Cheng, Hongmei,Zang, Cuicui,Sun, Bin,Jiang, Heyan,Bian, Fengxia
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supporting information
(2020/03/30)
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- Copper(II) complex with oxazoline ligand: Synthesis, structures and catalytic activity for nitro compounds reduction
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The Cu(II) complexes bearing bisoxazolines, tridentate pincer pybox and terpyridine ligands have been synthesized and fully characterized. The molecular structures of copper complexes 1a and 1c were confirmed by single-crystal X-ray diffraction methods. These copper complexes highly catalyzed nitro compounds reduction to aniline and its derivatives in the presence of NaBH4 reducing agent in water solvent. The complex 1e was an efficient catalyst toward nitro compounds reduction with wide functional group substrate scope and aliphatic nitro compounds.
- Du, Jun,Gao, Li-Li,Jia, Wei-Guo,Li, Mei,Zhi, Xue-Ting
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- Synthesis, characterization, and catalytic activity of half-sandwich ruthenium complexes with pyridine/phenylene bridged NHC = E (NHC = N-heterocyclic carbene, E = S, Se) ligands
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Three half-sandwichruthenium(II) complexes with pyridine/phenylene bridged NHC = E (NHC = N-heterocyclic carbene, E = S, Se) ligands [Ru(p-cymene)L](PF6)1–2 (1a–1c, L = ligand) were synthesized and characterized. All ruthenium complexes were fully characterized by 1H and 13C NMR spectra, mass spectrometry, and single-crystalX-ray diffraction methods. Moreover, the half-sandwich ruthenium complexes with NHC = E ligands showed highly catalytic activities towards to the tandem dehydrogenation of ammonia borane (AB) and hydrogenation of R–NO2 to R–NH2 at 353 K in water.
- Jia, Wei-Guo,Du, Teng-Teng,Gao, Li-Li,Du, Jun
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- Cerium-Catalyzed C-H Functionalizations of Alkanes Utilizing Alcohols as Hydrogen Atom Transfer Agents
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Modern photoredox catalysis has traditionally relied upon metal-to-ligand charge-transfer (MLCT) excitation of metal polypyridyl complexes for the utilization of light energy for the activation of organic substrates. Here, we demonstrate the catalytic application of ligand-to-metal charge-transfer (LMCT) excitation of cerium alkoxide complexes for the facile activation of alkanes utilizing abundant and inexpensive cerium trichloride as the catalyst. As demonstrated by cerium-catalyzed C-H amination and the alkylation of hydrocarbons, this reaction manifold has enabled the facile use of abundant alcohols as practical and selective hydrogen atom transfer (HAT) agents via the direct access of energetically challenging alkoxy radicals. Furthermore, the LMCT excitation event has been investigated through a series of spectroscopic experiments, revealing a rapid bond homolysis process and an effective production of alkoxy radicals, collectively ruling out the LMCT/homolysis event as the rate-determining step of this C-H functionalization.
- An, Qing,Chen, Yuegang,Liu, Weimin,Pan, Hui,Wang, Xin,Wang, Ziyu,Zhang, Kaining,Zuo, Zhiwei
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p. 6216 - 6226
(2020/04/27)
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- Hydrogen-Bond Catalysis of Imine Exchange in Dynamic Covalent Systems
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The reversibility of imine bonds has been exploited to great effect in the field of dynamic covalent chemistry, with applications such as preparation of functional systems, dynamic materials, molecular machines, and covalent organic frameworks. However, acid catalysis is commonly needed for efficient equilibration of imine mixtures. Herein, it is demonstrated that hydrogen bond donors such as thioureas and squaramides can catalyze the equilibration of dynamic imine systems under unprecedentedly mild conditions. Catalysis occurs in a range of solvents and in the presence of many sensitive additives, showing moderate to good rate accelerations for both imine metathesis and transimination with amines, hydrazines, and hydroxylamines. Furthermore, the catalyst proved simple to immobilize, introducing both reusability and extended control of the equilibration process.
- Schaufelberger, Fredrik,Seigel, Karolina,Ramstr?m, Olof
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p. 15581 - 15588
(2020/10/02)
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- Modulation of imine chemistry with intramolecular hydrogen bonding: Effects from ortho-OH to NH
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Salicylaldehyde derivatives and their imines are important building blocks in organic and supramolecular chemistry. In an effort to expand structural diversity in the current work we changed ortho-OH in salicylaldehyde to NH of amide/sulfonamide and investigated the effect of resulting intramolecular hydrogen bonds on imine dynamic covalent chemistry (DCC). A suite of ortho-aminobenzaldehydes were readily synthesized, and X-ray and NMR data validated the existence of NH?O intramolecular hydrogen bonds. The formation and exchange of imines were then studied in acetonitrile, and the acidity of OH/NH significantly influenced the thermodynamics and kinetics of imine reactions. Furthermore, the role of OH/NH?N hydrogen bonds on imines was elucidated by the shift of aldehyde exchange equilibrium. Finally, the formation of imines was achieved in aqueous solutions. The mechanistic insights could pave the way for future applications in assembly and labelling.
- Chen, Hang,Feng, Zelin,Jia, Shuaipeng,You, Lei
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supporting information
(2020/03/24)
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- Mild deprotection of the: N-tert -butyloxycarbonyl (N -Boc) group using oxalyl chloride
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We report a mild method for the selective deprotection of the N-Boc group from a structurally diverse set of compounds, encompassing aliphatic, aromatic, and heterocyclic substrates by using oxalyl chloride in methanol. The reactions take place under room temperature conditions for 1-4 h with yields up to 90percent. This mild procedure was applied to a hybrid, medicinally active compound FC1, which is a novel dual inhibitor of IDO1 and DNA Pol gamma. A broader mechanism involving the electrophilic character of oxalyl chloride is postulated for this deprotection strategy. This journal is
- Awuah, Samuel G.,George, Nathaniel,Ofori, Samuel,Parkin, Sean
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p. 24017 - 24026
(2020/07/23)
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- One-pot reductive amination of carboxylic acids: a sustainable method for primary amine synthesis
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The reductive amination of carboxylic acids is a very green, efficient and sustainable method for the production of (bio-based) amines. However, with current technology, this reaction requires two to three reaction steps. Here, we report the first (heterogeneous) catalytic system for the one-pot reductive amination of carboxylic acids to amines, with solely H2 and NH3 as the reactants. This reaction can be performed with relatively cheap ruthenium-tungsten bimetallic catalysts in the green and benign solvent cyclopentyl methyl ether (CPME). Selectivities of up to 99% for the primary amine could be achieved at high conversions. Additionally, the catalyst is recyclable and tolerant for common impurities such as water and cations (e.g. sodium carboxylate).
- Coeck, Robin,De Vos, Dirk E.
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supporting information
p. 5105 - 5114
(2020/08/25)
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- Na2S-promoted reduction of azides in water: Synthesis of pyrazolopyridines in one pot and evaluation of antimicrobial activity
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Reduction of various azides using Na2S has been accomplished in water, and, in situ, the resulting amines on reaction with various ketones lead to pyrazolo[3,4-b]pyridines in one pot. Thus, a number of new trifluoromethyl-substituted pyrazolo[3,4-b]pyridine compounds have been prepared and screened for antimicrobial activity against different Gram-positive and Gram-negative strains. A good number of compounds, 4a, 4b, 4d, 4f, 4i, 4k, 4l, 4m, 4r and 4s, were found to possess promising activity. Notably, Na2S on hydrolysis in water generates H2S and NaOH, which facilitate the reduction of azides followed by intramolecular cyclization leading to the title compounds. To the best of our knowledge, this is the first report of the synthesis of the title compounds in aqueous medium in a one-pot reaction.
- Kale, Ashok,Medishetti, Nagaraju,Kanugala, Sirisha,Ganesh Kumar,Atmakur, Krishnaiah
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p. 3186 - 3194
(2019/03/26)
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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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