100-12-9Relevant articles and documents
Palladium-catalyzed cross-methylation of aryl chlorides by stabilized dimethylaluminium and -gallium reagents
Blum, Jochanan,Berlin, Olga,Milstein, David,Ben-David, Yehoshua,Wassermann, Birgit C.,Schutte, Stefan,Schumann, Herbert
, p. 571 - 575 (2000)
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.
Well-structured bimetallic surface capable of molecular recognition for chemoselective nitroarene hydrogenation
Furukawa, Shinya,Takahashi, Katsuya,Komatsu, Takayuki
, p. 4476 - 4484 (2016)
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.
Highly Efficient Ultralow Pd Loading Supported on MAX Phases for Chemoselective Hydrogenation
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.
, p. 5899 - 5908 (2020)
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.
Aromatic Substitution. 471. Acid-Catalyzed Transfer Nitration of Aromatics with N-Nitropyrazole, a Convenient New Nitrating Agent
Olah, George A.,Narang, Subhash C.,Fung, Alexander P.
, p. 2706 - 2709 (1981)
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.
Polymethylhydrosiloxane reduction of carbonyl function catalysed by titanium tetrachloride
Jumbam, Ndze D.,Makaluza, Siyavuya,Masamba, Wayiza
, p. 179 - 184 (2018)
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.
In Situ Construction of Pt–Ni NF?Ni-MOF-74 for Selective Hydrogenation of p-Nitrostyrene by Ammonia Borane
Feng, Jing,Liu, Yu,Long, Yan,Song, Shuyan,Xu, Jinhui,Yang, Xiangguang,Zhang, Hongjie,Zhang, Yibo,Zhu, Junjiang
, (2020)
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.
Poly(4-vinylpyridine)-nitrating mixture complex (PVP-NM): Solid nitrating mixture equivalent for safe and efficient aromatic nitration
Surya Prakash,Gurung, Laxman,Glinton, Kevin E.,Belligund, Kavita,Mathew, Thomas,Olah, George A.
, p. 3446 - 3451 (2015)
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.
PARA-SELECTIVE MONONITRATION OF ALKYLBENZENES UNDER MILD CONDITIONS BY USE OF BENZOYL NITRATE IN THE PRESENCE OF A ZEOLITE CATALYST
Smith, Keith,Fry, Karl,Butters, Michael,Nay, Barry
, p. 5333 - 5336 (1989)
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.
Nitrogen-enriched porous carbon supported Pd-nanoparticles as an efficient catalyst for the transfer hydrogenation of alkenes
Li, Jie,Zhou, Xin,Shang, Ning-Zhao,Feng, Cheng,Gao, Shu-Tao,Wang, Chun
, p. 16823 - 16828 (2018)
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.
Palladium-Catalyzed Cross-Coupling Reaction of Organoindiums with Aryl Halides in Aqueous Media
Takami, Kazuaki,Yorimitsu, Hideki,Shinokubo, Hiroshi,Matsubara, Seijiro,Oshima, Koichiro
, p. 1997 - 1998 (2001)
(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.
User-friendly methylation of aryl and vinyl halides and pseudohalides with DABAL-Me3
Cooper, Thea,Novak, Andrew,Humphreys, Luke D.,Walker, Matthew D.,Woodward, Simon
, p. 686 - 690 (2006)
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.
Amorphous/Crystalline Hetero-Phase Pd Nanosheets: One-Pot Synthesis and Highly Selective Hydrogenation Reaction
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
, (2018)
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.
Chemoselective hydrogenation of nitrostyrene to aminostyrene over Pd- and Rh-based intermetallic compounds
Furukawa, Shinya,Yoshida, Yurika,Komatsu, Takayuki
, p. 1441 - 1450 (2014)
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.
The First Friedel-Crafts Reaction of Nitrobenzene
Shen, Yu-sheng,Lui, Hong-xia,Chen, Yi-qiu
, p. 3961 - 3962 (1990)
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Preparation of microporous polymer-encapsulated Pd nanoparticles and their catalytic performance for hydrogenation and oxidation
Ishida, Tamao,Onuma, Yuta,Kinjo, Kota,Hamasaki, Akiyuki,Ohashi, Hironori,Honma, Tetsuo,Akita, Tomoki,Yokoyama, Takushi,Tokunaga, Makoto,Haruta, Masatake
, p. 6150 - 6155 (2014)
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.
Easily-controlled chemoselective hydrogenation by using palladium on boron nitride
Yabe, Yuki,Sawama, Yoshinari,Yamada, Tsuyoshi,Nagata, Saori,Monguchi, Yasunari,Sajiki, Hironao
, p. 2360 - 2366 (2013)
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.
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Hoshino et al.
, p. 718,719, 721 (1978)
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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
Cheng, Saisai,Meng, Xufeng,Shang, Ningzhao,Gao, Shutao,Feng, Cheng,Wang, Chun,Wang, Zhi
, p. 1771 - 1778 (2018)
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.
Silica-dendrimer core-shell microspheres with encapsulated ultrasmall palladium nanoparticles: Efficient and easily recyclable heterogeneous nanocatalysts
Biradar, Ankush V.,Biradar, Archana A.,Asefa, Tewodros
, p. 14408 - 14418 (2011)
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.
Pt Nanoparticles Supported over Porous Porphyrin Nanospheres for Chemoselective Hydrogenation Reactions
Modak, Arindam,Bhanja, Piyali,Bhaumik, Asim
, p. 1977 - 1985 (2019)
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.
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Vavon,Mitchovitch
, p. 966 (1929)
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Direct Deamination of Primary Amines via Isodiazene Intermediates
Berger, Kathleen J.,Driscoll, Julia L.,Yuan, Mingbin,Dherange, Balu D.,Gutierrez, Osvaldo,Levin, Mark D.
supporting information, p. 17366 - 17373 (2021/11/04)
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.
Method for continuously synthesizing 4-ethylnitrobenzene and 2-ethylnitrobenzene
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Paragraph 0081-0103, (2020/08/09)
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
