- Palladium-catalyzed cross-methylation of aryl chlorides by stabilized dimethylaluminium and -gallium reagents
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Two methods for palladium-catalyzed cross-methylation of aryl chlorides by intramolecularly stabilized dialkylaluminium and -gallium complexes 6-13 have been studied. In one method, in which either tetrakis(triphenylphosphine)palladium (1) or dichloro- bis(triphenylphosphine)palladium (2) is used as the catalyst at 80-90°C, the activation of the chlorine atom is affected by introduction of strong electron-withdrawing groups into the aromatic moiety. The second method is based on the application of either [1,3- bis(diisopropylphosphino)propane)]palladium (4) or homologous electron-rich palladium complexes as catalysts. Although 4 promotes smooth cross-alkylation of aryl chlorides it fails to activate simple aryl bromides.
- Blum, Jochanan,Berlin, Olga,Milstein, David,Ben-David, Yehoshua,Wassermann, Birgit C.,Schutte, Stefan,Schumann, Herbert
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- Increased conversion and selectivity of 4-nitrostyrene hydrogenation to 4-aminostyrene on Pt nanoparticles supported on titanium-tungsten mixed oxides
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A catalyst series consisting in platinum nanoparticles photodeposited on pure titania and on W/Ti mixed oxides, these latter prepared by the sol-gel method, were tested in the hydrogenation of 4-nitrostyrene. A remarkable increase in the reaction rate occurred when the catalyst support contained tungsten, with a parallel boosting in the selective reduction of the nitro group. With the selective W-containing catalysts, the reaction proceeded at constant rate (zero order rate law), while the tungsten-free catalyst showed a rate-dependence on the 4-nitrostyrene concentration (positive order reaction). The presence of tungsten in the support is beneficial not only because a higher surface area is obtained, thanks to the stabilization of anatase owing to the presence of tungsten, but also because it allows the photodeposition of smaller, better dispersed platinum particles, on which the adsorption of the aromatic part of 4-nitrostyrene is less favored. Tungsten not only substitutes titanium in the titania lattice, as revealed by HAAF-STEM analysis, but it is also present as WOx species partly covering the Pt nanoparticles photodeposited on the mixed oxide support, as revealed by an in depth distribution XPS analysis. This accounts for the progressively lower performance observed with increasing tungsten content in the catalysts, the highest conversion and selective hydrogenation of the 4-nitrostyrene nitro group having been achieved on the catalyst with a 1% W/Ti molar ratio.
- Carrus, Marco,Fantauzzi, Marzia,Riboni, Francesca,Makosch, Martin,Rossi, Antonella,Selli, Elena,Van Bokhoven, Jeroen A.
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- Well-structured bimetallic surface capable of molecular recognition for chemoselective nitroarene hydrogenation
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Unprecedented molecular recognition ability governed by a simple bimetallic surface is reported. A series of Rh-based ordered alloys supported on silica gel (RhxMy/SiO2, where M is Bi, Fe, Ga, Ge, In, Ni, Pb, Sb, Sn, or Zn) were tested in the hydrogenation of nitrostyrene to form aminostyrene. RhIn/SiO2 showed remarkably high catalytic activity and good selectivity under 1 atm H2 at room temperature. Moreover, various other nitroarenes containing carbonyl, cyano, or halo moieties were selectively hydrogenated into the corresponding amino derivatives using RhIn/SiO2. Kinetic study and density functional theory (DFT) calculations revealed that the high selectivity originates from RhIn/SiO2 adsorbing nitro groups much more favorably than vinyl groups. In addition, the DFT calculations indicated that the RhIn ordered alloy presents concave Rh rows and convex In rows on its surface, which are able to capture the nitro group with end-on geometry while effectively minimizing vinyl-π adsorption. Thus, the specific and highly ordered surface structure of RhIn enables the chemoselective molecular recognition of nitro groups over vinyl groups through geometric and chemical effects.
- Furukawa, Shinya,Takahashi, Katsuya,Komatsu, Takayuki
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- REGIOSELECTIVE NITRATION OF AROMATIC HYDROCARBONS BY METALLIC NITRATES ON THE K10 MONTMORILLONITE UNDER MENKE CONDITIONS
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Aromatic hydrocarbons are nitrated with good regioselectivities by clay-supported cupric nitrate in the presence of acetic anhydride.The procedure commends itself by its simplicity and gives useful yields (75-98percent).In each case, the predominant product can be predicted by consideration of the Hueckel HOMO for the aromatic ring.
- Laszlo, Pierre,Vandormael, Joseph
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- Highly Efficient Ultralow Pd Loading Supported on MAX Phases for Chemoselective Hydrogenation
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Palladium is one of the most efficient metals for the hydrogenation of organic compounds. However, when molecules, such as nitroaromatics, with several reducible functionalities, are hydrogenated, Pd, like any other very active metal, such as nickel or platinum, often behaves unselectively. One strategy to render Pd more selective is to choose the proper support. Herein, we show that MAX phase powders of Ti3SiC2, Ti2AlC, or Ti3AlC2 can chemoselectively hydrogenate 4-nitrostyrene to 4-aminostyrene, with 100% selectivity, at around 3-4% conversion. To boost the latter, we loaded Ti3SiC2 with 0.0005 wt % Pd and increased the conversion to 100% while maintaining the 4-AS selectivity at >90%. By optimizing the Pd loading, we were also able to increase the turnover frequency 100-fold relative to previous literature results. The identification of this highly efficient and chemoselective system has broad implications for the design of cost-effective, earth-abundant, nontoxic, metal catalysts, with ultralow noble metal loadings.
- Barsoum, Michel W.,Chirica, Iuliana M.,Cucolea, Elena I.,Florea, Mihaela,Kuncser, Andrei C.,Natu, Varun,Nea?u, ?tefan,Nea?u, Florentina,Trandafir, Mihaela M.
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- Highly efficient iron(0) nanoparticle-catalyzed hydrogenation in water in flow
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Highly efficient catalytic hydrogenations are achieved by using amphiphilic polymer-stabilized Fe(0) nanoparticle (Fe NP) catalysts in ethanol or water in a flow reactor. Alkenes, alkynes, aromatic imines and aldehydes were hydrogenated nearly quantitatively in most cases. Aliphatic amines and aldehydes, ketone, ester, arene, nitro, and aryl halide functionalities are not affected, which provides an interesting chemoselectivity. The Fe NPs used in this system are stabilized and protected by an amphiphilic polymer resin, providing a unique system that combines long-term stability and high activity. The NPs were characterized by TEM of microtomed resin, which established that iron remains in the zero-valent form despite exposure to water and oxygen. The amphiphilic resin-supported Fe(0) nanoparticles in water and in flow provide a novel, robust, cheap and environmentally benign catalyst system for chemoselective hydrogenations.
- Hudson, Reuben,Hamasaka, Go,Osako, Takao,Yamada, Yoichi M. A.,Li, Chao-Jun,Uozumi, Yasuhiro,Moores, Audrey
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- Aromatic Substitution. 471. Acid-Catalyzed Transfer Nitration of Aromatics with N-Nitropyrazole, a Convenient New Nitrating Agent
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N-Nitropyrazole in the presence of Lewis or Bronsted acid catalysts was found to be an effective transfer nitrating agent for aromatic substrates.The nature of the acid catalyst both substrate and positional selectivies of the nitration of alkylbenzenes.No relationship was found between substrate and positional selectivities, which are considered to be determined in two separate steps.
- Olah, George A.,Narang, Subhash C.,Fung, Alexander P.
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- Rational Control of the Selectivity of a Ruthenium Catalyst for Hydrogenation of 4-Nitrostyrene by Strain Regulation
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Tuning the selectivity of metal catalysts is of paramount importance yet a great challenge. A new strategy to effectively control the selectivity of metal catalysts, by tuning the lattice strain, is reported. A certain amount of Co atoms is introduced into Ru catalysts to compress the Ru lattice, as confirmed by aberration-corrected high-resolution transmission electron microscopy (HRTEM) and X-ray absorption fine structure (XAFS) measurements. We discover that the lattice strain of Ru catalysts can greatly affect their selectivity, and Ru with 3 % lattice compression exhibits extremely high catalytic selectivity for hydrogenation of 4-nitrostyrene to 4-aminostyrene compared to pristine Ru (99 % vs. 66 %). Theoretical studies confirm that the optimized lateral compressive strain facilitates hydrogenation of the nitro group but impedes the hydrogenation of the vinyl group. This study provides a new guideline for designing metal catalysts with high selectivity.
- Mao, Junjie,Chen, Wenxing,Sun, Wenming,Chen, Zheng,Pei, Jiajing,He, Dongsheng,Lv, Chunlin,Wang, Dingsheng,Li, Yadong
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- Polymethylhydrosiloxane reduction of carbonyl function catalysed by titanium tetrachloride
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Reduction of aromatic aldehydes and ketones into the corresponding methylene derivatives by polymethylhydrosiloxane in the presence of titanium tetrachloride as catalyst was achieved in good to excellent yields ranging from 55-90%. The reaction took place under relatively mild conditions and smoothly led to the desired target molecules in the presence of other functional groups such as halogens, hydroxyl, nitro and methoxy groups. However, in the reduction of the substrate with two methoxy groups in close proximity (1,2-positions), the reaction necessitated a larger amount of the titanium catalyst and a longer reaction time to complete the reduction of the carbonyl function due to a likely complex formation of titanium tetrachloride with the methoxy groups.
- Jumbam, Ndze D.,Makaluza, Siyavuya,Masamba, Wayiza
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- In Situ Construction of Pt–Ni NF?Ni-MOF-74 for Selective Hydrogenation of p-Nitrostyrene by Ammonia Borane
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Pt–Ni nanoframes (Pt–Ni NFs) exhibit outstanding catalytic properties for several reactions owing to the large numbers of exposed surface active sites, but its stability and selectivity need to be improved. Herein, an in situ method for construction of a core–shell structured Pt-Ni NF?Ni-MOF-74 is reported using Pt–Ni rhombic dodecahedral as self-sacrificial template. The obtained sample exhibits not only 100 % conversion for the selective hydrogenation of p-nitrostyrene to p-aminostyrene conducted at room temperature, but also good selectivity (92 %) and high stability (no activity loss after fifteen runs) during the reaction. This is attributed to the Ni-MOF-74 shell in situ formed in the preparation process, which can stabilize the evolved Pt–Ni NF and donate electrons to the Pt metals that facilitate the preferential adsorption of electrophilic NO2 group. This study opens up new vistas for the design of highly active, selective, and stable noble-metal-containing materials for selective hydrogenation reactions.
- Feng, Jing,Liu, Yu,Long, Yan,Song, Shuyan,Xu, Jinhui,Yang, Xiangguang,Zhang, Hongjie,Zhang, Yibo,Zhu, Junjiang
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- Regioselectivity of the mononitration of alkylbenzenes by immobilized acyl nitrates
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Mononitration of alkylbenzenes was studied using acyl nitrates and trimethylsilyl nitrate supported on clay-minerals. Chrysotile gave higher performance than other materials. High para-selectivity was obtained with the supported reagents. Nitration of tol
- Augusto,Rodrigues,Pedro Oliveira Filho,Moran, Paulo J. S.
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- Poly(4-vinylpyridine)-nitrating mixture complex (PVP-NM): Solid nitrating mixture equivalent for safe and efficient aromatic nitration
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Friedel-Crafts type aromatic nitration has served as an indispensable reaction within both industrial and academic applications. However, growing concern over the use of copious amounts of strong acids has prompted the search for more environmentally friendly alternatives. Polymer-bound Bronsted acids, on the other hand, have been shown useful as convenient alternatives to liquid acids. Nitric acid and sulfuric acids have, therefore, been combined, both individually and as a mixture, with poly(4-vinylpyridine). The new solid acid systems have been used to nitrate both activated and deactivated arenes under mild conditions and proved to be effective nitrating agent.
- Surya Prakash,Gurung, Laxman,Glinton, Kevin E.,Belligund, Kavita,Mathew, Thomas,Olah, George A.
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- Palladium-catalyzed cross-coupling alkylation of arenediazonium o-benzenedisulfonimides
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Arenediazonium o-benzenedisulfonimides were reacted with tetramethyltin, tetrabutyltin or trialkylboranes. The reactions, carried out in the presence of palladium(II) derivatives as precatalysts, gave the methylation and alkylation products with good over
- Barbero, Margherita,Cadamuro, Silvano,Dughera, Stefano
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- PARA-SELECTIVE MONONITRATION OF ALKYLBENZENES UNDER MILD CONDITIONS BY USE OF BENZOYL NITRATE IN THE PRESENCE OF A ZEOLITE CATALYST
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Toluene and other alkylbenzenes are mononitrated in essentially quantitative yield at ambient temperature by benzoyl nitrate in the presence of aluminium/proton exchanged large port mordenite; the reaction is highly para-selective.
- Smith, Keith,Fry, Karl,Butters, Michael,Nay, Barry
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- Preparation of a ternary Pd-Rh-P amorphous alloy and its catalytic performance in selective hydrogenation of alkynes
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Palladium-rhodium-phosphorus amorphous alloy nanoparticles (～5.2 nm) were prepared via a facile one-pot synthesis method, exhibiting excellent catalytic behaviour in selective hydrogenation of alkynes under mild conditions. The Royal Society of Chemistry 2014.
- Ren, Mengrui,Li, Changming,Chen, Jiale,Wei, Min,Shi, Shuxian
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- Nitrogen-enriched porous carbon supported Pd-nanoparticles as an efficient catalyst for the transfer hydrogenation of alkenes
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Ultrafine palladium nanoparticles were immobilized on nitrogen-enriched porous carbon nanosheets (NPC), which were fabricated with g-C3N4 as a nitrogen source and a self-sacrificial template. The prepared Pd@NPC exhibited superior catalytic activity and chemoselectivity for the catalytic transfer hydrogenation of alkenes under mild conditions with formic acid as a hydrogen donor. Moreover, the catalyst displays high structure stability, and can be reused for five runs without any significant decrease of its catalytic activity and obvious leaching of Pd species. This work provides a facile and feasible approach to fabricate nitrogen-enriched carbon nanosheets and to construct advanced Pd supported heterogeneous catalysts for achieving high catalytic activity.
- Li, Jie,Zhou, Xin,Shang, Ning-Zhao,Feng, Cheng,Gao, Shu-Tao,Wang, Chun
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- Synergistic effects for enhanced catalysis in a dual single-atom catalyst
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Synergistic effects have been discussed extensively in bimetallic heterogeneous catalysis, but it remains unclear how the effects function at the atomic scale. Here, we report a dual single-atom catalyst (DSAC) Ir1Mo1/TiO2 displaying much greater catalytic chemoselectivity (>96%, at 100% conversion) than comparable single-atom catalysts (SACs) Ir1/TiO2 (38%, at 87% conversion) and Mo1/TiO2 (no activity) for the hydrogenation of 4-nitrostyrene (4-NS) to 4-vinylaniline (4-VA). Activation of the TiO2-supported bimetallic carbonyl cluster Ir2Mo2(CO)10(η5- C5H5)2 in an Ar atmosphere affords the DSAC Ir1Mo1/TiO2. Characterization of the dual single-atom structure confirms that it consists of well-dispersed Ir single atoms (Ir1) and Mo single atoms (Mo1) on TiO2. Density functional theory studies reveal that Ir1 sites effect H2 activation while Mo1 sites are responsible for 4-NS adsorption, with synergistic cooperation between the two sets of single atoms contributing to the better catalytic performance for the hydrogenation of 4-NS. This work provides a deep understanding of synergistic effects in dual single-atom catalysis.
- Fu, Junhong,Dong, Jinhu,Si, Rui,Sun, Keju,Zhang, Junying,Li, Mingrun,Yu, Nana,Zhang, Bingsen,Humphrey, Mark G.,Fu, Qiang,Huang, Jiahui
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- Palladium-Catalyzed Cross-Coupling Reaction of Organoindiums with Aryl Halides in Aqueous Media
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(matrix presented) Diaryl-, divinyl-, and dialkylindium proved to be stable in aqueous media and to undergo a palladium-catalyzed cross-coupling reaction with aryl halides in aqueous THF. Treatment of 3-iodophenol with diphenylindium compound, generated from indium trichloride and two equimolar amounts of a phenyl Grignard reagent, in aqueous media under palladium catalysis provided the corresponding coupling product in excellent yield. Divinyl- and diethlindium can be used for the coupling reaction in the presence of water. A wide range of functional groups, including a hydroxy group and a formyl group, are compatible with this reaction.
- Takami, Kazuaki,Yorimitsu, Hideki,Shinokubo, Hiroshi,Matsubara, Seijiro,Oshima, Koichiro
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- A mild and efficient rhenium-catalyzed transfer hydrogenation of terminal olefins using alcoholysis of amine-borane adducts as a reducing system
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[ReBr2(NO)(CH3CN)(PTA)2] (PTA = 1, 3, 5-triaza-7-phosphaadamantane) catalyzes the alcoholysis of ammonia-borane and amine-boranes and the catalytic transfer hydrogenations of various terminal olefins. Excellent yields were achieved at 70 °C in isopropanol using tBuOK as a co-catalyst affording TOF values up to 396 h-1.
- Dong, Hailin,Berke, Heinz
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- User-friendly methylation of aryl and vinyl halides and pseudohalides with DABAL-Me3
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An extremely technically simple cross-methylation of aryl and vinyl halides and pseudohalides using an air-stable adduct of trimethylaluminium with a Pd(0) catalyst supported by commercially available biarylphosphines gives excellent yields of methylated products (mainly > 95%). Reactions can be run with either 0.5 mol% catalyst or without requiring the exclusion of atmospheric oxygen or the drying of solvents in some cases. A wide variety of functional groups is tolerated including CN, OH, CO2R, CHO and NO2.
- Cooper, Thea,Novak, Andrew,Humphreys, Luke D.,Walker, Matthew D.,Woodward, Simon
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- Chemoselective hydrogenation of unsaturated nitro compounds to unsaturated amines by Ni-Sn alloy catalysts
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Ni-Sn alloy catalysts were prepared and applied to the hydrogenation of 4-nitrostyrene at 383423 K using H2 gas as the hydrogen donor. Ni3Sn2 alloy showed a significantly high conversion and selectivity towards 4-aminostyrene (Conv. 100%, Sel. 99%). Various unsaturated nitro compounds were also successfully converted into their corresponding unsaturated amines.
- Yamanaka, Nobutaka,Hara, Takayoshi,Ichikuni, Nobuyuki,Shimazu, Shogo
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- Amorphous/Crystalline Hetero-Phase Pd Nanosheets: One-Pot Synthesis and Highly Selective Hydrogenation Reaction
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Similar to heterostructures composed of different materials, possessing unique properties due to the synergistic effect between different components, the crystal-phase heterostructures, one variety of hetero-phase structures, composed of different crystal phases in monometallic nanomaterials are herein developed, in order to explore crystal-phase-based applications. As novel hetero-phase structures, amorphous/crystalline heterostructures are highly desired, since they often exhibit unique properties, and hold promise in various applications, but these structures have rarely been studied in noble metals. Herein, via a one-pot wet-chemical method, a series of amorphous/crystalline hetero-phase Pd nanosheets is synthesized with different crystallinities for the catalytic 4-nitrostyrene hydrogenation. The chemoselectivity and activity can be fine-tuned by controlling the crystallinity of the as-synthesized Pd nanosheets. This work might pave the way to preparing various hetero-phase nanostructures for promising applications.
- Yang, Nailiang,Cheng, Hongfei,Liu, Xiaozhi,Yun, Qinbai,Chen, Ye,Li, Bing,Chen, Bo,Zhang, Zhicheng,Chen, Xiaoping,Lu, Qipeng,Huang, Jingtao,Huang, Ying,Zong, Yun,Yang, Yanhui,Gu, Lin,Zhang, Hua
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- Disilaruthena- and Ferracyclic Complexes Containing Isocyanide Ligands as Effective Catalysts for Hydrogenation of Unfunctionalized Sterically Hindered Alkenes
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Disilaferra- and disilaruthenacyclic complexes containing mesityl isocyanide as a ligand, 3′ and 4′, were synthesized and characterized by spectroscopy and crystallography. Both 3′ and 4′ showed excellent catalytic activity for the hydrogenation of alkenes. Compared with iron and ruthenium carbonyl analogues, 1′ and 2′, the isocyanide complexes 3′ and 4′ were more robust under the hydrogenation conditions, and were still active even at higher temperatures (～80 °C) under high hydrogen pressure (～20 atm). The iron complex 3′ exhibited the highest catalytic activity toward hydrogenation of mono-, di-, tri-, and tetrasubstituted alkenes among currently reported iron catalysts. Ruthenium complex 4′ catalyzed hydrogenation under very mild conditions, such as room temperature and 1 atm of H2. The remarkably high catalytic activity of 4′ for hydrogenation of unfunctionalized tetrasubstituted alkenes was especially notable, because it was comparable to the activity of iridium complexes reported by Crabtree and Pfaltz, which are catalysts with the highest activity in the literature. DFT calculations suggested two plausible catalytic cycles, both of which involved activation of H2 assisted by the metal-silicon bond through σ-bond metathesis of late transition metals (oxidative hydrogen migration). The linear structure of M C≡N - C (ipso carbon of the mesityl group) played an essential role in the efficient hydrogenation of sterically hindered tetrasubstituted alkenes.
- Sunada, Yusuke,Ogushi, Hajime,Yamamoto, Taiji,Uto, Shoko,Sawano, Mina,Tahara, Atsushi,Tanaka, Hiromasa,Shiota, Yoshihito,Yoshizawa, Kazunari,Nagashima, Hideo
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- Chemoselective hydrogenation of nitrostyrene to aminostyrene over Pd- and Rh-based intermetallic compounds
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A noble catalytic system based on intermetallic compounds was developed for the chemoselective hydrogenation of p-nitrostyrene (NS) to p-aminostyrene (AS). The main concept of the catalyst design was to construct polar active sites consisting of two types of metals with different electronegativities. We prepared a series of Pd- and Rh-based intermetallics and investigated their catalytic properties in detail in the catalytic transfer hydrogenation of nitrobenzene and NS in the presence of 4-methyl-1-cyclohexene (MC) or methanol as a hydrogen donor. FT-IR studies of adsorbed CO confirmed that the number of Pd ensembles exposed on a surface was greatly decreased by the formation of an intermetallic phase; hence, the particle surface consisted of two metal elements being coadjacent at the atomic level. The product distribution achieved with Pd catalysts was dependent on the electronegativity of the second metal element: more electronegative metals gave higher AS selectivity and lower p-ethylnitrobenzene selectivity. Rh catalysts selectively gave AS, and their AS yields increased as the electronegativity of the second metal increased. The results revealed that an increase in the electronegativity of the second metal element provided polar sites and enhanced the activation of methanol as a hydrogen donor, which accelerated the hydrogenation of the nitro group of NS and, hence, improved the yield of AS. The high selectivity of Rh catalysts was due to the absence of MC activation ability, which caused the hydrogenation of the vinyl group of NS. Pd13Pb9 exhibited the highest chemoselectivity toward AS (92%) among the investigated Pd catalysts. Moreover, RhPb2 exhibited not only high AS selectivity (93%) but also the highest NS conversion (94%) among the investigated catalysts. RhPb2 also exhibited high selectivity toward AS (91%), even when H2 was used as a hydrogen source. Thus, intermetallics that contain Pb, which was the most electronegative metal used in this study, afforded good catalytic performance and were observed to be good catalysts for the chemoselective hydrogenation of NS.
- Furukawa, Shinya,Yoshida, Yurika,Komatsu, Takayuki
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- On-Demand, Ultraselective Hydrogenation System Enabled by Precisely Modulated Pd-Cd Nanocubes
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The pursuit of efficient hydrogenation nanocatalysts with a desirable selectivity toward intricate substrates is state-of-the-art research but remains a formidable challenge. Herein, we report a series of novel PdCdx nanocubes (NCs) for ultraselective hydrogenation reactions with flexible tuning features. Obtaining a desirable conversion level of the substrates (e.g., 4-nitrophenylacetylene (NPA), 4-nitrobenzaldehyde (NBAD), and 4-nitrostyrene (NS)) and competitive selectivity for all potential hydrogenation products have been achieved one by one under optimized hydrogenation conditions. The performance of these PdCdx NCs displays an evident dependence on both the composition and the use of Cd and a need for a distinct hydrogen source (H2 or HCOONH4). Additionally, for the selectivity of hydrogen to be suitably high, the morphology of the NCs has a very well-defined effect. Density functional theory calculations confirmed the variation of adsorption energy for the substrate and hydrogenation products by carefully controlled introduction of Cd, leading to a desirable level of selectivity for all potential hydrogenation products. The PdCdx NCs also exhibit excellent reusability with negligible activity/selectivity decay and structural/composition changes after consecutive reactions. The present study provides an advanced strategy for the rational design of superior hydrogenation nanocatalysts to achieve a practical application for desirable and selective hydrogenation reaction efficiency.
- Feng, Yonggang,Xu, Weiwei,Huang, Bolong,Shao, Qi,Xu, Lai,Yang, Shize,Huang, Xiaoqing
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- Palladium nanoparticles in situ generated in metal-organic films for catalytic applications
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Palladium nanoparticles were first in situ generated in metal-organic films for catalytic applications. Layer-by-layer assembly of metal-organic films consisting of rigid-rod chromophores connected by terminal pyridine moieties to palladium centers on solid substrates was presented. Bipyridyl and polypyridyl ligands were used as building blocks to explore the influence of different ligand structures on catalytic properties. Metal-organic films were characterized by UV-Vis spectra, atomic force microscopy (AFM), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). The results show that the deposition mechanism of metal-organic films is perfect layer-by-layer self-assembling with complete surface coverage and regular growth. Moreover, the catalytic activity toward the hydrogenation of olefin was investigated. Based on XPS and TEM, the catalytic activity toward the hydrogenation of olefin was ascribed to the in situ formation of Pd nanoparticles from Pd ions in metal-organic films. This film material is an active catalyst for the hydrogenation of olefin under mild conditions. Furthermore, catalytic results indicated that monodentate bipyridyl ligands exhibited superior catalytic activity than tridentate polypyridyl ligands. Catalytic activity is related to the loading amount of catalysts and permeability. More importantly, this study points toward the potential application of metal-organic films as heterogeneous catalysts with easy separation and good recyclability. This journal is the Partner Organisations 2014.
- Gao, Shuiying,Cao, Minna,Li, Weijin,Cao, Rong
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- Preparation of microporous polymer-encapsulated Pd nanoparticles and their catalytic performance for hydrogenation and oxidation
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Palladium nanoparticles (Pd NPs) encapsulated by conjugated microporous polymers (CMPs) were prepared by the Pd-catalyzed polymerization followed by a thermal treatment with N2or H2. The Pd catalysts were embedded in the porous network during polymerization and used as a precursor for the generation of Pd NPs in CMP. Although no Pd NPs were formed in the as-synthesized Pd/CMPs, Pd NPs with 1.6-3.5 nm size were formed after the thermal treatment. The obtained Pd/CMP-N2and -H2catalysts were highly selective in the hydrogenation of 4-nitrostyrene to 4-ethylnitrobenzene, whereas Pd NPs supported on carbon (Ketjen black) gave a fully reduced product, 4-ethylaniline. Substituents in CMP framework could change the catalytic activity of Pd NPs; hydroxy-substituted CMP encapsulated Pd NPs showed higher catalytic activity than Pd/CMP-H2for benzyl alcohol oxidation.
- Ishida, Tamao,Onuma, Yuta,Kinjo, Kota,Hamasaki, Akiyuki,Ohashi, Hironori,Honma, Tetsuo,Akita, Tomoki,Yokoyama, Takushi,Tokunaga, Makoto,Haruta, Masatake
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- Mild and selective hydrogenation of nitro compounds using palladium nanoparticles supported on amino-functionalized mesocellular foam
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We present the utilization of a heterogeneous catalyst comprised of Pd nanoparticles supported on aminopropyl-functionalized siliceous mesocellular foam (Pd0-AmP-MCF) for the selective hydrogenation of aromatic, aliphatic, and heterocyclic nitro compounds to the corresponding amines. In general, the catalytic protocol exclusively affords the desired amine products in excellent yields within short reaction times with the reactions performed at room temperature under ambient pressure of H2. Moreover, the reported Pd nanocatalyst displayed excellent structural integrity for this transformation as it could be recycled multiple times without any observable loss of activity or leaching of metal. In addition, the Pd nanocatalyst could be easily integrated into a continuous-flow device and used for the hydrogenation of 4-nitroanisole on a 2.5 g scale, where the product p-anisidine was obtained in 95% yield within 2 h with a Pd content of less than 1 ppm.
- Verho, Oscar,Gustafson, Karl P. J.,Nagendiran, Anuja,Tai, Cheuk-Wai,B?ckvall, Jan-E.
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- Easily-controlled chemoselective hydrogenation by using palladium on boron nitride
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The hydrogenation catalyzed heterogeneously by palladium on boron nitride (Pd/BN) in methanol realized the chemoselective hydrogenation of only azides, alkenes, and alkynes in the presence of other reducible functionalities such as benzyl ethers, aryl halides, aryl ketones, and nitro groups. Furthermore, the totally chemoselective semihydrogenation of alkynes could also be achieved without the reduction of other coexisting reducible functionalities, which include azides and alkenes, by using Pd/BN in pyridine as a solvent. Be unique, be selective: The chemoselective hydrogenation of azides, alkenes, and alkynes was achieved without the reduction of other reducible functionalities by the use of a heterogeneous palladium on boron nitride (Pd/BN) catalyst. Furthermore, Pd/BN was applicable to the unique and chemoselective semihydrogenation of alkynes without the reduction of azido functionalities in the presence of pyridine or diethylenetriamine.
- Yabe, Yuki,Sawama, Yoshinari,Yamada, Tsuyoshi,Nagata, Saori,Monguchi, Yasunari,Sajiki, Hironao
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- Chloride-free and water-soluble Au complex for preparation of supported small nanoparticles by impregnation method
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A novel simple and easy impregnation method for preparation of small gold (Au) nanoparticle (NP) catalysts (3+. Lower decomposition and reduction temperature of the chloride-free Au complex prevented Au atoms from aggregating and from following growth of Au particles. The prepared Au/SiO2 showed high selectivity for hydrogenation of 1-nitro-4-vinylbenzene into 1-ethyl-4-nitorobenzene and good performance for removal of unpalatable aroma by means of adsorption of polysulfide molecules.
- Murayama, Haruno,Hasegawa, Takayuki,Yamamoto, Yusuke,Tone, Misaki,Kimura, Moemi,Ishida, Tamao,Honma, Tetsuo,Okumura, Mitsutaka,Isogai, Atsuko,Fujii, Tsutomu,Tokunaga, Makoto
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- Application of Pd Nanoparticles Supported on Mesoporous Hollow Silica Nanospheres for the Efficient and Selective Semihydrogenation of Alkynes
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Herein, the preparation of a heterogeneous catalyst consisting of 1-2 nm sized Pd nanoparticles supported on amino-functionalized mesoporous hollow silica nanospheres and its use for the semihydrogenation of mono- And disubstituted alkynes is reported. By utilizing this Pd nanocatalyst together with the green poisoning agent DMSO, high yields of the desired alkenes could be achieved, while suppressing the degree of over-reduction to alkanes. To our delight, the Pd nanocatalyst displayed remarkable chemoselectivity towards the alkyne moiety, allowing the transformation to be carried out in the presence of other reducible functionalities, such as halogens, carbonyl, and nitro groups.
- Verho, Oscar,Zheng, Haoquan,Gustafson, Karl P. J.,Nagendiran, Anuja,Zou, Xiaodong,B?ckvall, Jan-E.
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- Pd supported on g-C3N4 nanosheets: Mott-Schottky heterojunction catalyst for transfer hydrogenation of nitroarenes using formic acid as hydrogen source
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Well-dispersed Pd nanoparticles were anchored on g-C3N4 nanosheets, which were prepared by a liquid-phase exfoliation method. The hybrid material displayed excellent catalytic activity for the transfer hydrogenation of nitroarenes. The reactions can be conducted smoothly in water at room temperature with formic acid as hydrogen source. Aniline was produced in excellent yield (>99%; turnover frequency: 853), surpassing the majority of reported heterogeneous catalysts using formic acid or formates as hydrogen source. The increased activity of such a hybrid catalyst can be ascribed to the nitrogen-rich and amphipathic property of the carbon nitride support, the stable and uniform dispersed Pd nanoparticles and the Mott-Schottky effect between the g-C3N4 nanosheets and the metal nanoparticles. The heterogeneous Mott-Schottky catalyst can be reused for five cycles without any obvious loss of its catalytic activity.
- Cheng, Saisai,Meng, Xufeng,Shang, Ningzhao,Gao, Shutao,Feng, Cheng,Wang, Chun,Wang, Zhi
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- Silica-dendrimer core-shell microspheres with encapsulated ultrasmall palladium nanoparticles: Efficient and easily recyclable heterogeneous nanocatalysts
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We report the synthesis, characterization, and catalytic properties of novel monodisperse SiO2@Pd-PAMAM core-shell microspheres containing SiO2 microsphere cores and PAMAM dendrimer-encapsulated Pd nanoparticle (Pd-PAMAM) shells. First, SiO2 microspheres, which were prepared by the Stoeber method, were functionalized with vinyl groups by grafting their surfaces with vinyltriethoxysilane (VTS). The vinyl groups were then converted into epoxides by using m-chloroperoxybenzoic acid. Upon treatment with amine-terminated G4 poly(amidoamine) (PAMAM) dendrimers, the SiO 2-supported epoxides underwent ring-opening and gave SiO 2@PAMAM core-shell microspheres. Pd nanoparticles within the cores of the SiO2-supported PAMAM dendrimers were synthesized by letting Pd(II) ions complex with the amine groups in the cores of the dendrimers and then reducing them into Pd(0) with NaBH4. This produced the SiO 2@Pd-PAMAM core-shell microspheres. The presence of the different functional groups on the materials was monitored by following the changes in FTIR spectra, elemental analyses, and weight losses on thermogravimetric traces. Transmission electron microscopy (TEM) images showed the presence of Pd nanoparticles with average size of 1.56 ± 0.67 nm on the surface of the monodisperse SiO2@Pd-PAMAM core-shell microspheres. The SiO 2@Pd-PAMAM core-shell microspheres were successfully used as an easily recyclable catalyst for hydrogenation of various olefins, alkynes, keto, and nitro groups, giving ～100% conversion and high turnover numbers (TONs) under 10 bar H2 pressure, at room temperature and in times ranging from 10 min to 3 h. In addition, the SiO2@Pd-PAMAM core-shell microspheres were proven to be recyclable catalysts up to five times with barely any leaching of palladium into the reaction mixture.
- Biradar, Ankush V.,Biradar, Archana A.,Asefa, Tewodros
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- THE SELECTIVITY OF ELECTROPHILIC AROMATIC NITRATION AND THE EFFECT OF THE ORGANIC SOLVENTS
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The nitrating agent prepared by mixing Bu4NNO3 and (CF3CO)2O has been used to nitrate in homogeneous conditions eight aromatic substrates, ranging in reactivity from benzene to mesitylene, in several organic solvents.From competitive kinetic experiments and glc analysis, partial rate factors were obtained.The nature of the solvent significantly affects selectivity in the whole activation range.Selectivity was quantitatively measured by the selectivity factor for toluene, and, more properly, by the slopes in the correlations between log values of partial rate factors in a given solvent and the corresponding values in a reference solvent.Good correlations were obtained also including ortho positions and polysubstituted substrates, and the following order of relative selectivity could be established: MeNO2 MeCN /= sulfolane CH2ClCH2Cl CH2Cl2 /= EtOAc /= i-PrBr = n-BuCl = n-BuBr /= CHCl3.Correlation between partial rate factors has been extended to compare the selectivity of different nitrating agents in the same solvent, and the method can be used to ascertain whether the same electrophilic species actually operates in the two systems.
- Masci, Bernardo
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- Pt Nanoparticles Supported over Porous Porphyrin Nanospheres for Chemoselective Hydrogenation Reactions
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Optimizing the chemoselectivity in a chemical reaction catalyzed by metallic nanoparticles (NPs) hosted over a solid support is a big challenge, especially in the context of the sustainability of the process. Here we showed that chemoselectivity in the hydrogenation of 4-nitrostyrene can be tailored on Pt-loaded porphyrin nanospheres through the functionalization with sulfonic acid groups at the catalyst surface. 4-Nitrostyrene is transformed to 4-aminostyrene over sulfonated Pt-POP-SO3H, with ～77.8 % selectivity at conversion of ～90 %, whereas the pristine catalyst selectively produced ～80 % 4-ethylnitrobenezene at almost complete conversion level. The reversal of the selectivity could be attributed to the effect of the introduction of sulfonic acid group over the supported Pt NPs. Presence of sulfonic acid groups in the functionalized Pt-porphyrin material has been confirmed from XPS, FT-IR and elemental analysis data. Moreover, these catalysts are recyclable, suggesting their durability and chemical-stability for long-term sustainable operations.
- Modak, Arindam,Bhanja, Piyali,Bhaumik, Asim
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- Alkylation of nitroaromatics with trialkyborane
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When p-dinitrobenzene is reacted with Et3B in t-BuOH or THF in the presence oft-BuOK, it yields p-nitroethylbenzene. In this report we examine the scope of this transformation by monitoring the effect of various parameters on the reaction. It has been found that the reaction is extremely sensitive to temperature and rather insensitive to the base-solvent combination used. It is also insensitive to the steric hindrance of the base: good yields were obtained using sodium 2,6-diisopropylphenoxide or when using NaH. Alkylation was obtained With a large variety of alkylboranes ranging from linear to polycyclic. Yields drop significantly if one of the nitro groups is replaced by another electron-withdrawing group. In all cases studied (CHO, PHCO, SO2Ph, and CN), it is the latter group which was preferentially displaced by the alkyl group. According to the suggested mechanism, the radical anion of the substrate combines with the alkyl radical released from the boranyl radical to form a Meisenheimer complex. The reaction takes place at the ring carbon bearing the highest spin density in accordance with ab initio calculations at the B3LYP/ 6-31+G level.
- Palani,Jayaprakash, Karamil,Hoz, Shmaryahu
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- Reduction of carbonyl to methylene: Organosilane-Ga(OTf)3 as an efficient reductant system
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Direct carbonyl reduction to methylene has been achieved by mild reductant system obtained from the combination of organosilane and gallium (III) trifluoromethanesulfonate {Ga(OTf)3}, a water tolerant, recyclable, catalyst. Among a series of organosilanes studied, dimethylchlorosilane (Me 2SiHCl, DMCS) showed the highest efficiency. Both aromatic and aliphatic ketones were effectively reduced to the corresponding methylene products with high functional groups tolerance, under very mild conditions in a relatively short period of time with good to excellent yields. Graphical Abstract: [Figure not available: see fulltext.]
- Surya Prakash,Do, Clement,Mathew, Thomas,Olah, George A.
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- Direct Deamination of Primary Amines via Isodiazene Intermediates
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We report here a reaction that selectively deaminates primary amines and anilines under mild conditions and with remarkable functional group tolerance including a range of pharmaceutical compounds, amino acids, amino sugars, and natural products. An anomeric amide reagent is uniquely capable of facilitating the reaction through the intermediacy of an unprecedented monosubstituted isodiazene intermediate. In addition to dramatically simplifying deamination compared to existing protocols, our approach enables strategic applications of iminium and amine-directed chemistries as traceless methods. Mechanistic and computational studies support the intermedicacy of a primary isodiazene which exhibits an unexpected divergence from previously studied secondary isodiazenes, leading to cage-escaping, free radical species that engage in a chain, hydrogen-atom transfer process involving aliphatic and diazenyl radical intermediates.
- Berger, Kathleen J.,Driscoll, Julia L.,Yuan, Mingbin,Dherange, Balu D.,Gutierrez, Osvaldo,Levin, Mark D.
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supporting information
p. 17366 - 17373
(2021/11/04)
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- Solar-accelerated chemoselective hydrogenation of 4-nitrostyrene to 4-vinylaniline with carbon dot-induced Cu over Cu3P in the absence of any sacrificial reagent
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We present an efficient method toward rational design and fabrication of multicomponent photocatalysts using carbon dots (CDs) for solar-driven chemical reactions with super selectivity and activity. CDs act not only as a reductant to enable metallic Cu formation but also as a hole trapping agent to hinder side reactions. By simple pyrolysis of the mixture of the Cu source, CDs and NaH2PO2, the Cu3P-CDs-Cu nanocomposite is produced and shows a good sunlight harvesting property. Under one sun irradiation, Cu3P-CDs-Cu can catalyze ammonia borane (AB) for selective hydrogenation of 4-nitrostyrene (4-NS) to 4-aminostyrene (4-AS) in an aqueous solvent at room temperature, achieving 100% selectivity and beyond 99% conversion rate within a few short minutes of reaction time. The superior performance of Cu3P-CDs-Cu is attributed to the formation of the all-solid-state Z-scheme photocatalytic system, eliminating the high-energy holes - active species attacking CC groups in 4-NS - from Cu3P. Meanwhile, metallic Cu promotes the migration and transport of excited electrons from the interior to the surface and interface, accelerating the activation of AB for selective reduction of 4-NS to 4-AS.
- Chang, Qing,Hao, Caihong,Hu, Shengliang,Li, Ning,Ren, Yuqi,Yang, Jinlong
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supporting information
p. 25374 - 25380
(2021/12/07)
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- Method for continuously synthesizing 4-ethylnitrobenzene and 2-ethylnitrobenzene
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The invention belongs to the technical field of chemical engineering, and particularly relates to a method for continuously synthesizing 4-ethylnitrobenzene and 2-ethylnitrobenzene by adopting a micro-channel reactor. The method sequentially comprises the
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Paragraph 0081-0103
(2020/08/09)
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- Hydrogenation reaction method
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The invention relates to a hydrogenation reaction method, and belongs to the technical field of organic synthesis. The hydrogenation reaction method provided by the invention comprises the following steps: carrying out a hydrogen transfer reaction on a hydrogen acceptor compound, pinacol borane and a catalyst in a solvent in the presence of proton hydrogen, so that the hydrogen acceptor compound is subjected to a hydrogenation reaction; the catalyst is one or more than two of a palladium catalyst, an iridium catalyst and a rhodium catalyst; the hydrogen acceptor compound comprises one or morethan two functional groups of carbon-carbon double bonds, carbon-carbon triple bonds, carbon-oxygen double bonds, carbon-nitrogen double bonds, nitrogen-nitrogen double bonds, nitryl, carbon-nitrogentriple bonds and epoxy. The method is mild in reaction condition, easy to operate, high in yield, short in reaction time, wide in substrate application range, suitable for carbon-carbon double bonds,carbon-carbon triple bonds, carbon-oxygen double bonds, carbon-nitrogen double bonds, nitrogen-nitrogen double bonds, nitryl, carbon-nitrogen triple bonds and epoxy functional groups, good in selectivity and high in reaction specificity.
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Paragraph 0034; 0165-0168
(2020/05/14)
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- Generalized Chemoselective Transfer Hydrogenation/Hydrodeuteration
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A generalized, simple and efficient transfer hydrogenation of unsaturated bonds has been developed using HBPin and various proton reagents as hydrogen sources. The substrates, including alkenes, alkynes, aromatic heterocycles, aldehydes, ketones, imines, azo, nitro, epoxy and nitrile compounds, are all applied to this catalytic system. Various groups, which cannot survive under the Pd/C/H2 combination, are tolerated. The activity of the reactants was studied and the trends are as follows: styrene'diphenylmethanimine'benzaldehyde'azobenzene'nitrobenzene'quinoline'acetophenone'benzonitrile. Substrates bearing two or more different unsaturated bonds were also investigated and transfer hydrogenation occurred with excellent chemoselectivity. Nano-palladium catalyst in situ generated from Pd(OAc)2 and HBPin extremely improved the TH efficiency. Furthermore, chemoselective anti-Markovnikov hydrodeuteration of terminal aromatic olefins was achieved using D2O and HBPin via in situ HD generation and discrimination. (Figure presented.).
- Wang, Yong,Cao, Xinyi,Zhao, Leyao,Pi, Chao,Ji, Jingfei,Cui, Xiuling,Wu, Yangjie
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supporting information
p. 4119 - 4129
(2020/08/10)
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- Copper-catalyzed formal transfer hydrogenation/deuteration of aryl alkynes
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A copper-catalyzed reduction of alkynes to alkanes and deuterated alkanes is described under transfer hydrogenation and transfer deuteration conditions. Commercially available alcohols and silanes are used interchangeably with their deuterated analogues as the hydrogen or deuterium sources. Transfer deuteration of terminal and internal aryl alkynes occurs with high levels of deuterium incorporation. Alkyne-containing complex natural product analogues undergo transfer hydrogenation and transfer deuteration selectively, in high yield. Mechanistic experiments support the reaction occurring through a cis-alkene intermediate and demonstrate the possibility for a regioselective alkyne transfer hydrodeuteration reaction.
- Sloane, Samantha E.,Reyes, Albert,Vang, Zoua Pa,Li, Lingzi,Behlow, Kiera T.,Clark, Joseph R.
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supporting information
p. 9139 - 9144
(2020/11/30)
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- Base promoted peroxide systems for the efficient synthesis of nitroarenes and benzamides
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A useful and efficient approach for the synthesis of nitroarenes from several aromatic amines (including heterocycles) using peroxide and base has been developed. This oxidative reaction is very easy to handle and afforded the products in good yields. Formation of benzamides from benzylamine was also successfully carried out with this metal-free catalytic system in good to excellent yields.
- Gupta, Sampa,Ansari, Alisha,Sashidhara, Koneni V.
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supporting information
(2019/09/07)
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- Spirobifluorene-based Porous Organic Polymers as Efficient Porous Supports for Pd and Pt for Selective Hydrogenation
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Spirobifluorene-based porous organic polymers (POP) were synthesized following two different protocols; the acetylenic coupling reaction conditions and the Sonogashira cross-coupling reaction. These were utilized as support for the hydrogenation of a series of species containing unsaturated C=C and C=O bonds (4-nitrostyrene, 4-bromobenzophenone, acetophenone, 7-nitro-1-tetralone and 1,2-naphtoquinone confirmed their efficiency). POP1 prepared via a copper-catalysis protocol was completely inactive, while POP2-4 containing residual Pd exhibited different activities in accordance to the accessibility of the substrates to the metal. Further deposition of 0.5 wt% Pd led to active and stable catalysts. They were easily separated by filtration, and after re-dispersion, afforded the same performances for ten successive cycles. This study also evidenced the specific role of the support in these reactions by comparing the behavior of Pd/POP with that of a Pd/C catalyst with the same loading of palladium. The deposition of Pt on these supports led to sub-nanometric particles and, in accordance, to a different catalytic behavior reflected merely by differences in the selectivity.
- Trandafir, Mihaela Mirela,Pop, Lidia,H?dade, Niculina D.,Hristea, Ioana,Teodorescu, Cristian Mihail,Krumeich, Frank,van Bokhoven, Jeroen A.,Grosu, Ion,Parvulescu, Vasile I.
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p. 538 - 549
(2018/10/09)
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- Iridium-Catalyzed Alkene-Selective Transfer Hydrogenation with 1,4-Dioxane as Hydrogen Donor
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The iridium-catalyzed transfer hydrogenation of alkenes using 1,4-dioxane as a hydrogen donor is described. The use of 1,2-bis(dicyclohexylphosphino)ethane (DCyPE), featuring bulky and highly electron-donating properties, led to high catalytic activity. A polystyrene-cross-linking bisphosphine PS-DPPBz produced a reusable heterogeneous catalyst. These homogeneous and heterogeneous protocols achieved chemoselective transfer hydrogenation of alkenes over other potentially reducible functional groups such as carbonyl, nitro, cyano, and imino groups in the same molecule.
- Zhang, Deliang,Iwai, Tomohiro,Sawamura, Masaya
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supporting information
p. 5867 - 5872
(2019/08/26)
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- Catalytic Materials Based on Surface Coating with Poly(ethyleneimine)-Stabilized Gold Nanoparticles
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Gold nanoparticles (AuNPs) can be obtained from HAuCl4 by using poly(ethyleneimine) (PEI) as both reductant and stabilizing agent. However, the known affinity of PEI for different materials has not been exploited to coat them and turn their surface catalytic. We demonstrate that the irradiation of a solution of HAuCl4 and branched PEI 1800 (bPEI2K) with microwave (MW) yields PEI-stabilized AuNPs (MW-PEI@AuNPs) with an average size of 7.6 nm that are catalytically active in the reduction with NaBH4 of different nitroarenes functionalized with a variety of functional groups. Moreover, the as-prepared MW-PE@-AuNPs show affinity for different materials such as polystyrene (standard spectrophotometry disposal cuvettes), polypropylene (Falcon-type tubes), and silica (Silica gel 60), turning their surface catalytic without any additional synthetic step. This feature was exploited to transform standard tubing (Tygon, poly(ether ether ketone), and stainless steel) into flow reactors by simple passage of a solution of MW-PEI@AuNPs. This straightforward functionalization is especially appealing in the case of the stainless-steel tubing, one of the materials more widely used in HPLC, which is of interest for flow nanocatalysis.
- Ortega-Mu?oz, Mariano,Blanco, Victor,Hernandez-Mateo, Fernando,Lopez-Jaramillo, F. Javier,Santoyo-Gonzalez, Francisco
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p. 3965 - 3973
(2017/09/14)
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- Regioselective mononitration of aromatic compounds with N2O5 by acidic ionic liquids via continuous flow microreactor
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We employed N2O5 as highly active nitrating reagents and a host of acidic ionic liquid as catalysts in these reactions which were conducted in a continuous flow microreactor. When we utilized PEG400-DAIL as catalysts, the conversion of toluene was increased to 95.5 % and the yield of mononitration product (o/p ratio reached 1.10) significantly improved to 99 %, meanwhile the reaction time was drastically shortened to 1/120 of the conventional reactor. Nitration in ionic liquids was surveyed using a host of aromatic substrates with similar reactivity. The ionic liquid recycling procedures had also been devised.
- Liu, Jianhua,Li, Bindong,Wang, Huan
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p. 513 - 516
(2016/01/20)
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- NITRATION OF AROMATIC COMPOUNDS
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The present invention provides a process for nitrating aromatic compounds without the need for a solid catalyst and/or any organic solvents and/or any other additives. A typical process includes combining or admixing a nitric acid and an anhydride compound under conditions sufficient to produce a reactive intermediate. The aromatic compound to be nitrated is then added to this reactive intermediate to produce a nitroaromatic compound. The nitroaromatic compound can be substituted with one or more, typically, one to three, and often one or two nitrate (-NO2) groups.
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Paragraph 0049
(2016/08/17)
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- Tetrahydroxydiboron-Mediated Palladium-Catalyzed Transfer Hydrogenation and Deuteriation of Alkenes and Alkynes Using Water as the Stoichiometric H or D Atom Donor
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There are few examples of catalytic transfer hydrogenations of simple alkenes and alkynes that use water as a stoichiometric H or D atom donor. We have found that diboron reagents efficiently mediate the transfer of H or D atoms from water directly onto unsaturated C-C bonds using a palladium catalyst. This reaction is conducted on a broad variety of alkenes and alkynes at ambient temperature, and boric acid is the sole byproduct. Mechanistic experiments suggest that this reaction is made possible by a hydrogen atom transfer from water that generates a Pd-hydride intermediate. Importantly, complete deuterium incorporation from stoichiometric D2O has also been achieved.
- Cummings, Steven P.,Le, Thanh-Ngoc,Fernandez, Gilberto E.,Quiambao, Lorenzo G.,Stokes, Benjamin J.
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supporting information
p. 6107 - 6110
(2016/06/09)
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- Eco-friendly nitration of benzenes over zeolite-β-SBA-15 composite catalyst
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Direct synthesis of microporous-mesoporous zeolite-β-SBA-15 (ZBS-15) composite catalyst from the synthetic precursors of SBA-15and zeolite-β seeds under acidic hydrothermal conditions through the simultaneous self-assembly of mesoporous silica SBA-15 and zeolite-β has been accomplished and characterized the ZBS-15 catalyst by XRD, N2 sorption, FT-IR, TPD of ammonia and SEM techniques. The activity of the ZBS-15 composite catalyst for the nitration of benzenes under solvent-free conditions has been investigated, which revealed that there is a significant synergistic influence of both zeolite-β and SBA-15 materials on the activity of the ZBS-15 catalyst.
- Ganjala, Venkata Siva Prasad,Neeli, Chinna Krishna Prasad,Pramod, Chodimella Venkata,Khagga, Mukkanti,Rao, Kamaraju Seetha Rama,Burri, David Raju
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- Bismuth triflate catalyzed mononitration of aromatic compounds with N 2O5
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This page isvestigated that bismuth triflate catalysed the nitration of a range of simple aromatic compounds in good to excellent yields at 0-30 °C within 2 h using N2O5 and the catalyst can be recycled without apparent loss of activity. Mechanistic insights demonstrate that triflic acid is generated and that, at least, when two competing catalytic cycles are operating at the same time: a rapid one involving triflic acid and a slower one involving the bismuth triflate.
- Qian, Hua,Wang, Ya,Liu, Dabin,Lv, Chunxu
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p. 509 - 512
(2014/05/20)
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- Regioselective dinitration of simple aromatics over zeolite Hβ/nitric acid/acid anhydride systems
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Various nitration systems comprising nitric acid, acid anhydride and zeolite H￡] in the absence of solvent are described. Direct double nitration of toluene with a nitric acid, propanoic anhydride and zeolite Hβ system has been developed to give 2,4-dinitrotoluene in 98% yield, with a 2,4-:2,6-dinitrotoluene ratio of 123:1. This system also nitrates activated mono-substituted benzenes (anisole and phenetole) and moderately activated mono-substituted benzenes (ethylbenzene and propylbenzene) to give mainly 2,4-dinitro derivatives. The zeolite can be recovered, regenerated and reused to give almost the same yield as that given when fresh zeolite is used. ARKAT-USA, Inc.
- Smith, Keith,Alotaibi, Mohammad Hayal,El-Hiti, Gamal A.
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p. 107 - 123
(2014/04/17)
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- Preparation of microporous polymer-encapsulated Pd nanoparticles and their catalytic performance for hydrogenation and oxidation
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Palladium nanoparticles (Pd NPs) encapsulated by conjugated microporous polymers (CMPs) were prepared by the Pd-catalyzed polymerization followed by a thermal treatment with N2 or H2. The Pd catalysts were embedded in the porous network during polymerization and used as a precursor for the generation of Pd NPs in CMP. Although no Pd NPs were formed in the as-synthesized Pd/CMPs, Pd NPs with 1.6-3.5 nm size were formed after the thermal treatment. The obtained Pd/CMP-N2 and -H2 catalysts were highly selective in the hydrogenation of 4-nitrostyrene to 4-ethylnitrobenzene, whereas Pd NPs supported on carbon (Ketjen black) gave a fully reduced product, 4-ethylaniline. Substituents in CMP framework could change the catalytic activity of Pd NPs; hydroxy-substituted CMP encapsulated Pd NPs showed higher catalytic activity than Pd/CMP-H2 for benzyl alcohol oxidation.
- Ishida, Tamao,Onuma, Yuta,Kinjo, Kota,Hamasaki, Akiyuki,Ohashi, Hironori,Honma, Tetsuo,Akita, Tomoki,Yokoyama, Takushi,Tokunaga, Makoto,Haruta, Masatake
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p. 6150 - 6155
(2015/03/30)
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- Regioselective nitration of aromatics with nanomagnetic solid superacid SO42-/ZrO2-MxOy-Fe 3O4 and its theoretical studies
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A series of micro- and nanosulfated zirconia loaded on Fe3O 4 or other metal oxides (SO42-/ZrO 2-MxOy-Fe3O4 (M=Ti 4+, V5+, and Zn2+)) was prepared, characterized, and used in nitration. The nitration conditions with these solid superacids were then optimized to achieve the best regioselectivity and improve the performances of the catalysts as well. In the experimental results, SZTF (SO42-/ZrO2-TiO2-Fe 3O4) showed excellent catalytic activity and it increased the surface area of SO42-/ZrO2 by up to 15 %. The increase not only facilitated the generation of NO2+, but also provided more opportunities for metal ions to interact with aromatic compounds. With chlorobenzene as substrate, theoretical research on its geometric parameters, electron clouds, and electron spin density was used to investigate the interaction between transition metals and chlorobenzene.
- Wang, Peng Cheng,Zhu, Jie,Liu, Xiang,Lu, Ting Ting,Lu, Ming
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p. 310 - 317
(2013/08/23)
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- Preparation of heteropoly acid based amphiphilic salts supported by nano oxides and their catalytic performance in the nitration of aromatics
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A series of Keggin heteropoly acid anion based amphiphilic salts supported by nano oxides were synthesized and used as catalysts in the nitration of aromatic compounds with HNO3. The reaction conditions in the nitration of toluene were optimized and both 92.6% conversion and good para selectivity (ortho:para = 1.09) were obtained.
- Wang, Peng-Cheng,Yao, Kai,Lu, Ming
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p. 2197 - 2202
(2013/03/14)
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- Preparation, catalytic performance and theoretical study of porous sulfated binary metal oxides shell (SO42 -/M1xO y-M2xOy) using pollen grain templates
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Porous micro-sized particles of binary metal oxide (SO4 2 -/M1xOy-M2xOy) shell were prepared by template-directed synthesis method employing HCl-treated pollen grains. With 150 m2/g high surface area, these solid acids could provide more acid sites and thus obtain better catalytic activity. Using aromatic nitration as the typical reaction, their catalytic performances were evaluated and showed a significant improvement in both conversion and regioselectivity. Then, with chlorobenzene as substrate, theoretical studies were performed to investigate the interaction between transition metals and chlorobenzene. The results showed that the excellent para-selectivity was closely relative to the metal ion in these solid acids.
- Wang, Peng Cheng,Yao, Kai,Zhu, Jie,Liu, Xiang,Lu, Ting Ting,Lu, Ming
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- Efficient palladium-catalyzed C-O hydrogenolysis of benzylic alcohols and aromatic ketones with polymethylhydrosiloxane
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A simple method has been developed for the reductive deoxygenation of aromatic ketones and benzylic alcohols in the presence of polymethylhydrosiloxane (PMHS). The reductive deoxygenation of aromatic ketones and benzylic alcohols, including secondary alcohols, to the corresponding methylene hydrocarbons has been achieved in good to excellent yields using palladium chloride (PdCl2) as catalyst and PMHS as hydride source. Such deoxygenations were successfully with aryl alkyl ketones and diaryl ketones, as exemplified by the reductive deoxygenation of acetophenone and benzopheneone, respectively. The corresponding benzylic alcohols and secondary alcohol analogues could also be converted into their respective methylene hydrocarbons by the PdCl2/PMHS system.
- Wang, Hu,Li, Li,Bai, Xing-Feng,Shang, Jun-Yan,Yang, Ke-Fang,Xu, Li-Wen
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supporting information
p. 341 - 347
(2013/05/08)
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- Highly regioselective dinitration of toluene over reusable zeolite Hβ
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A nitration system comprising nitric acid, propanoic anhydride, and zeolite Hβ has been developed for dinitration of toluene to give 2,4-dinitrotoluene in 98% yield, with a 2,4-:2,6-dinitrotoluene ratio of over 120. This represents the most selective quantitative method for 2,4-dinitration of toluene; the catalyst is reusable, solvent is not needed, and an aqueous work-up is not required.
- Smith, Keith,Alotaibi, Mohammad Hayal,El-Hiti, Gamal A.
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p. 244 - 247
(2013/02/22)
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- Rare earth metal triflates catalyzed electrophilic nitration using N 2O5
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A mild, efficient and eco-friendly process for the electrophilic nitration is described using N2O5 as a green nitrating agent in the presence of rare earth metal triflates [RE(OTf)3] under mild conditions.
- Ma, Xiao Ming,Li, Bin Dong,Lu, Ming,Lv, Chun Xu
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experimental part
p. 73 - 76
(2012/03/26)
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- Selective nitration of aromatic compounds catalyzed by Hβ zeolite using N2O5
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A selective and efficient process for the electrophilic nitration is described using N2O5 as a green nitrating agent, Hβ zeolite as a solid acid catalyst and shape controlling agent under mild conditions.
- Ma, Xiao Ming,Li, Bin Dong,Chen, Lei,Lu, Ming,Lv, Chun Xu
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scheme or table
p. 809 - 812
(2012/08/08)
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- Aromatic nitration with bismuth nitrate in ionic liquids and in molecular solvents: A comparative study of Bi(NO3)3·5H 2O/[bmim][PF6] and Bi(NO3)3· 5H2O/1,2-DCE systems
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A suspension of bismuth nitrate pentahydrate (BN) in [bmim][PF6] or [bmim][BF4] imidazolium ionic liquid (IL) is an effective reagent for ring nitration of activated aromatics under mild conditions without the need for external promoters. Nitration can also be effected in 1,2-DCE, MeCN, or MeNO2 without additives. Nitration of activated arenes (anisole, toluene, ethylbenzene, cumene, p-xylene, mesitylene, durene, and 1,3-dimethoxybenzene) is considerably faster (time to completion) in BN/[bmim][PF6] relative to BN/1,2-DCE and there are also differences in isomer distributions (for anisole, toluene, and ethylbenzene). With introduction of strongly deactivating substituents (-CHO; -MeCO; -NO 2) the BN/IL system is no longer active but reactions still proceed with BN/1,2-DCE in reasonable yields. The ready availability and low cost of BN, simple operation, and absence of promoters, coupled to recycling and reuse of the IL, provide an attractive alternative to classical nitration methods for activated arenes. Switching from Bi(NO3)3·5H 2O/[bmim][PF6] to Bi(NO3)3· 5H2O/1,2-DCE increases the scope of the substrates that can be nitrated.
- Jacoway, Jonathan,Kumar, G. G. K. S. Narayana,Laali, Kenneth K.
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p. 6782 - 6785,4
(2012/12/12)
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- Reusable and efficient polystryrene-supported acidic ionic liquid catalyst for mononitration of aromatic compounds
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A series of polystyrene-supported 1-(propyl-3-sulfonate)-3-methyl- imidazolium hydrosulfate acidic ionic liquid (PS-[SO3H-PMIM][HSO 4]) catalysts were prepared and tested for mononitration of simple aromatics compounds with nitric acid. It was found that the reactivity of the catalysts increased with increasing [SO3HPMIM][ HSO4] content. The para-selectivity was not only related to the [SO 3H-PMIM][HSO4] content but also the substituent groups in aromatics. A reaction mechanism of nitration over this new catalyst was proposed. The catalytic activity of this catalyst decreased slightly after fifth runs in the synthesis of nitrotoluene.
- Li, Li Xia,Ling, Qi Long,Liu, Zu Liang,Xing, Xiao Dong,Zhu, Xiao Qin,Meng, Xiao
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p. 3373 - 3377
(2013/01/15)
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