52 research outputs found

    Graphenes in the absence of metals as carbocatalysts for selective acetylene hydrogenation and alkene hydrogenation

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    Catalysis makes possible a chemical reaction by increasing the transformation rate. Hydrogenation of carbon-carbon multiple bonds is one of the most important examples of catalytic reactions. Currently, this type of reaction is carried out in petrochemistry at very large scale, using noble metals such as platinum and palladium or first row transition metals such as nickel. Catalysis is dominated by metals and in many cases by precious ones. Here we report that graphene (a single layer of one-atom-thick carbon atoms) can replace metals for hydrogenation of carbon-carbon multiple bonds. Besides alkene hydrogenation, we have shown that graphenes also exhibit high selectivity for the hydrogenation of acetylene in the presence of a large excess of ethylene.This study was financially supported by the Spanish Ministry of Economy and Competitiveness (Severo Ochoa and CTQ2012-32315); and Generalidad Valenciana (Prometeo 21/013) is gratefully acknowledged.Primo Arnau, AM.; Neatu, F.; Florea, M.; Parvulescu, V.; García Gómez, H. (2014). Graphenes in the absence of metals as carbocatalysts for selective acetylene hydrogenation and alkene hydrogenation. Nature Communications. 5:1-9. https://doi.org/10.1038/ncomms6291S195Dreyer, D. R. & Bielawski, C. W. Carbocatalysis: heterogeneous carbons finding utility in synthetic chemistry. Chem. Sci. 2, 1233–1240 (2011).Machado, B. F. & Serp, P. Graphene-based materials for catalysis. Catal. Sci. Technol. 2, 54–75 (2012).Schaetz, A., Zeltner, M. & Stark, W. J. Carbon modifications and surfaces for catalytic organic transformations. ACS Catal. 2, 1267–1284 (2012).Su, D. S. et al. Metal-free heterogeneous catalysis for sustainable chemistry. ChemSusChem 3, 169–180 (2010).Chauhan, S. M. S. & Mishra, S. Use of graphite oxide and graphene oxide as catalysts in the synthesis of dipyrromethane and calix[4]pyrrole. Molecules 16, 7256–7266 (2011).Dreyer, D. R., Jarvis, K. A., Ferreira, P. J. & Bielawski, C. W. Graphite oxide as a carbocatalyst for the preparation of fullerene-reinforced polyester and polyamide nanocomposites. Polym. Chem. 3, 757–766 (2012).Dreyer, D. R., Park, S., Bielawski, C. W. & Ruoff, R. S. The chemistry of graphene oxide. Chem. Soc. Rev. 39, 228–240 (2010).Pyun, J. Graphene oxide as catalyst: application of carbon materials beyond nanotechnology. Angew. Chem. Int. Ed. 50, 46–48 (2011).Rourke, J. P. et al. The real graphene oxide revealed: stripping the oxidative debris from the graphene-like sheets. Angew. Chem. Int. Ed. 50, 3173–3177 (2011).Sun, H. et al. Reduced graphene oxide for catalytic oxidation of aqueous organic pollutants. ACS Appl. Mater. Interf. 4, 5466–5471 (2012).Dreyer, D. R., Jia, H. P. & Bielawski, C. W. Graphene oxide: a convenient carbocatalyst for facilitating oxidation and hydration reactions. Angew. Chem. Int. Ed. 49, 6813–6816 (2010).Dreyer, D. R., Jia, H. P., Todd, A. D., Geng, J. X. & Bielawski, C. W. Graphite oxide: a selective and highly efficient oxidant of thiols and sulfides. Org. Biomol. Chem. 9, 7292–7295 (2011).Hayashi, M. Oxidation using activated carbon and molecular oxygen system. Chem. Rec. 8, 252–267 (2008).Jia, H. P., Dreyer, D. R. & Bielawski, C. W. C-H oxidation using graphite oxide. Tetrahedron 67, 4431–4434 (2011).Kumar, A. V. & Rao, K. R. Recyclable graphite oxide catalyzed Friedel-Crafts addition of indoles to alpha, beta-unsaturated ketones. Tetrahedron Lett. 52, 5188–5191 (2011).Soria-Sanchez, M. et al. Carbon nanostructure materials as direct catalysts for phenol oxidation in aqueous phase. Appl. Catal. B Environ. 104, 101–109 (2011).Verma, S. et al. Graphene oxide: an efficient and reusable carbocatalyst for aza-Michael addition of amines to activated alkenes. Chem. Commun. 47, 12673–12675 (2011).Yu, H. et al. Solvent-free catalytic dehydrative etherification of benzyl alcohol over graphene oxide. Chem. Phys. Lett. 583, 146–150 (2013).Holschumacher, D., Bannenberg, T., Hrib, C. G., Jones, P. G. & Tamm, M. Heterolytic dihydrogen activation by a frustrated carbene-borane Lewis pair. Angew. Chem. Int. Ed. 47, 7428–7432 (2008).Staubitz, A., Robertson, A. P. M., Sloan, M. E. & Manners, I. Amine- and phosphine-borane adducts: new interest in old molecules. Chem. Rev. 110, 4023–4078 (2010).Stephan, D. W. & Erker, G. Frustrated Lewis Pairs: Metal-free Hydrogen Activation and More. Angew. Chem. Int. Ed. 49, 46–76 (2010).Poh, H. L., Sanek, F., Sofer, Z. & Pumera, M. High-pressure hydrogenation of graphene: towards graphane. Nanoscale 4, 7006–7011 (2012).Sofo, J. O., Chaudhari, A. S. & Barber, G. D. Graphane: A two-dimensional hydrocarbon. J. Phys. Chem. B 75, 153401 (2007).Elias, D. C. et al. Control of graphene’s properties by reversible hydrogenation: evidence for graphane. Science 323, 610–613 (2009).Despiau-Pujo, E. et al. Elementary processes of H2 plasma-graphene interaction: a combined molecular dynamics and density functional theory study. J. Appl. Phys. 113, 114302 (2013).Xu, L. & Ge, Q. Effects of defects and dopants in graphene on hydrogen interaction in graphene-supported NaAlH4. Int. J. Hydrogen Energy 38, 3670–3680 (2013).Perhun, T. I., Bychko, I. B., Trypolsky, A. I. & Strizhak, P. E. Catalytic properties of graphene material in the hydrogenation of ethylene. Theor. Exp. Chem. 48, 367–370 (2013).Hummers, W. S. & Offeman, R. E. Preparation of graphitic oxide. J. Am. Chem. Soc. 80, 1339 (1958).Dhakshinamoorthy, A., Primo, A., Concepcion, P., Alvaro, M. & Garcia, H. Doped graphene as a metal-free carbocatalyst for the selective aerobic oxidation of benzylic hydrocarbons, cyclooctane and styrene. Chem. Eur. J. 19, 7547–7554 (2013).Latorre-Sanchez, M., Primo, A. & Garcia, H. P-doped graphene obtained by pyrolysis of modified alginate as a photocatalyst for hydrogen generation from water-methanol mixtures. Angew. Chem. Int. Ed. 52, 11813–11816 (2013).Primo, A., Sanchez, E., Delgado, J. M. & Garcia, H. High-yield production of N-doped graphitic platelets by aqueous exfoliation of pyrolyzed chitosan. Carbon N. Y. 68, 777–783 (2014).Stankovich, S. et al. Synthesis of graphene-based nanosheets via chemical reduction of exfoliated graphite oxide. Carbon N. Y. 45, 1558–1565 (2007).Pumera, M. & Wong, C. H. A. Graphane and hydrogenated graphene. Chem. Soc. Rev. 42, 5987–5995 (2013).Teschner, D. et al. The roles of subsurface carbon and hydrogen in palladium-catalyzed alkyne hydrogenation. Science 320, 86–89 (2008).Bridier, B., Lopez, N. & Perez-Ramirez, J. Molecular understanding of alkyne hydrogenation for the design of selective catalysts. Dalton Trans. 39, 8412–8419 (2010).Flick, K., Herion, C. & Allmann, H. Palladium-haltiger Trägerkatalysator zur selektiven katalytischen Hydrierung von Acetylen in Kohlenwasserstoffströmen. EP764463-A; EP764463-A2; DE19535402-A1; JP9141097-A; CA2185721-A; KR97014834-A; MX9604031-A1; US5847250-A; US5856262-A; TW388722-A; MX195137-B; CN1151908-A; EP764463-B1; DE59610365-G; ES2197222-T3; KR418161-B; CN1081487-C; JP3939787-B2; CA2185721-C (1997).Gartside, R. J. et al. Improved olefin plant recovery system employing a combination of catalytic distillation and fixed bed catalytic steps. WO2005080530-A1; EP1711581-A1; BR200418414-A; MX2006008045-A1; JP2007518864-W; KR2007005565-A; CN1961059-A; IN200604063-P1; KR825662-B1; JP4376908-B2; CA2553962-C; IN251202-B; SG124072-A1; SG124072-B; CN1961059-B (2005).Wegerer, D. A., Bussche, K. V. & Vandenbussche, K. M. Selective Co oxidation for acetylene converter feed Co CONTROL. US2012294774-A1; US8431094-B2 (2102).Chernichenko, K. et al. A frustrated-Lewis-pair approach to catalytic reduction of alkynes to cis-alkenes. Nat. Chem. 5, 718–723 (2013).Vile, G., Bridier, B., Wichert, J. & Perez-Ramirez, J. Ceria in hydrogenation catalysis: high selectivity in the conversion of alkynes to olefins. Angew. Chem. Int. Ed. 51, 8620–8623 (2012).Ambrosi, A. et al. Metallic impurities in graphenes prepared from graphite can dramatically influence their properties. Angew. Chem. Int. Ed. 51, 500–503 (2012).Ambrosi, A. et al. Chemical reduced graphene contains inherent metallic impurities present in parent natural and synthetic graphite. Proc. Natl Acad. Sci. USA 109, 12899–12904 (2012).Vile, G., Almora-Barrios, N., Mitchell, S., Lopez, N. & Perez-Ramirez, J. From the lindlar catalyst to supported ligand-modified palladium nanoparticles: selectivity patterns and accessibility constraints in the continuous-flow three-phase hydrogenation of acetylenic compounds. Chemistry 20, 5849–5849 (2014).Gurrath, M. et al. Palladium catalysts on activated carbon supports—Influence of reduction temperature, origin of the support and pretreatments of the carbon surface. Carbon N. Y. 38, 1241–1255 (2000).Stephan, D. W. ‘Frustrated Lewis pairs’: a concept for new reactivity and catalysis. Org. Biomol. Chem. 6, 1535–1539 (2008).Stephan, D. W. Frustrated Lewis pairs: a new strategy to small molecule activation and hydrogenation catalysis. Dalton Trans. 17, 3129–3136 (2009).Chase, P. A., Jurca, T. & Stephan, D. W. Lewis acid-catalyzed hydrogenation: B(C6F5)3-mediated reduction of imines and nitriles with H2. Chem. Commun. 14, 1701–1703 (2008).Hounjet, L. J. & Stephan, D. W. Hydrogenation by frustrated Lewis pairs: main group alternatives to transition metal catalysts? Org. Process Res. Dev. 18, 385–391 (2014).Spies, P. et al. Metal-free catalytic hydrogenation of enamines, imines, and conjugated phosphinoalkenylboranes. Angew. Chem. Int. Ed. 47, 7543–7546 (2008).Greb, L. et al. Metal-free catalytic olefin hydrogenation: low-temperature H2 activation by frustrated Lewis pairs. Angew. Chem. Int. Ed. 51, 10164–10168 (2012)

    Estimated rate constants for hydrogen abstraction from n-heterocyclic carbene-borane complexes by an alkyl radical

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    Rate constants for hydrogen abstraction by a nonyl radical from 20 complexes of N-heterocyclic carbenes and boranes (NHC-boranes) have been determined by the pyridine-2-thioneoxycarbonyl (PTOC) competition kinetic method at a single concentration point. The rate constants range from <1 × 104 to 8 × 104 M-1 s-1. They show little dependence on the electronic properties of the carbene core, but there is a trend for increasing rate constants with decreasing size of the carbene N-substituents. Two promising new reagents with small N-substituents (R = Me) have been identified. © 2010 American Chemical Society

    Suzuki-miyaura coupling of NHC-Boranes: A new addition to the C-C coupling toolbox

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    Complexes of triaryl- and trialkylboranes with N-heterocyclic carbenes (NHCs) participate In Suzuki-Miyaura cross-coupling reactions and provide coupled products In good yields under base-free conditions. The reaction can be applied to Csp2-Csp2 and Csp2-Csp3 carbon-carbon bond formation with triflates, iodides, bromides, and chlorides. These results enrich the utility of NHC-borane complexes, which can be added to the toolkit of Suzukl-Miyaura cross-couplings, along with boronlc acids and organotrlfluoroborates. © 2009 American Chemical Society

    Metal-free hydrogen activation by the frustrated Lewis Pairs of ClB(C6F5)2 and HB(C6F5)2 and bulky Lewis bases

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    The frustrated Lewis pair (FLP) derived from ClB(C6F5)2 and the bulky Lewis bases 2,2,6,6-tetramethylpiperidine (TMP), tri-tert-butylphosphine, and tris(2,4,6-trimethylphenyl)phosphine cleaved H2 heterolytically to form the intermediate anion [HClB(C6F5)2]−, which quickly underwent hydride/chloride exchange with the remaining ClB(C6F5)2 to give the known compound [HB(C6F5)2]n (n = 1 or 2) and the anion [Cl2B(C6F5)2]− present in the products [TMPH][Cl2B(C6F5)2] (1a), [t-Bu3PH][Cl2B(C6F5)2] (2a), and [Mes3PH][Cl2B(C6F5)2] (3a). [HB(C6F5)2]n forms Lewis adducts with TMP and t-Bu3P: TMP-BH(C6F5)2 (1b) and t-Bu3P-BH(C6F5)2 (2b). The Lewis adduct t-Bu3P-BH(C6F5)2 was found capable of generating a FLP at elevated temperature and was reacted with H2, producing the splitting product [t-Bu3PH][H2B(C6F5)2] (2c). Mes3P forms no Lewis adduct with [HB(C6F5)2]n, but a FLP, which was also capable of splitting H2 to yield initially [Mes3PH][H2B(C6F5)2]. The [H2B(C6F5)2]− anion underwent disproportionation to form [Mes3PH][HB(C6F5)3] (3b), Mes3P, [H2B(C6F5)]2, and H2. Similarly, 2,4,6-tri-tert-butylpyridine (TTBP) and [HB(C6F5)2]n gave in the presence of H2 the final products [TTBPH][HB(C6F5)3] salt and [H2B(C6F5)]2. The contrasting reactivities of the t-Bu3P/[BH(C6F5)2]n, Mes3P/[HB(C6F5)2]n, and TTBP/[HB(C6F5)2]n pairs were explained on the basis of the different pKa’s of the [LBH]+ cations. After disproportionation of the [H2B(C6F5)2]− anion to give [Mes3PH][HB(C6F5)3] (3b) or [TTBPH][HB(C6F5)3] (4a), the also formed [H3B(C6F5)]− anion reacted with the more acidic cations ([Mes3PH]+, [TTBPH]+) to give H2 and syn- and anti-[H2B(C6F5)]2 (3c). 1a, 2a, 3a, and 4a were studied by single-crystal X-ray diffraction analysis