100-41-4

Solubilities and Hydrophobic Interactions in Aqueous Solutions of Monoalkylbenzene Molecules

Ben-Naim, A.,Wilf, J.

, p. 583 - 586 (1980)

Solubilities of a series of monoalkylbenzene molecules in water were determined spectroscopically at several temperatures.The standard free energies of transferring these solutes from the gas into the liquid phase were calculated.From these data we have estimated hydrophobic interaction between a methane molecule and the various alkyl residues of these solutes.

EFFECT OF COMPOSITION AND CALCINATION TEMPERATURE ON THE CATALYTIC PROPERTIES OF ULTRAHIGH-SILICA ZEOLITE IN ISOBUTYLENE CONVERSIONS

Minachev, Kh. M.,Kondrat'ev, D. A.,Nefedov, B. K.,Khodakov, Yu. S.,Bondarenko, T. N.,et al.

, p. 1042 - 1047 (1981)

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NHC complexes of cobalt(II) relevant to catalytic C-C coupling reactions

Przyojski, Jacob A.,Arman, Hadi D.,Tonzetich, Zachary J.

, p. 723 - 732 (2013)

Alkyl compounds of cobalt(II) containing aryl-substituted N-heterocyclic carbene ligands have been prepared by reaction of the precursor chloro complexes [CoCl2(IMes)2] and [Co2Cl2(μ-Cl) 2(IPr)2] (IMes = 1,3-dimesityl-imidazol-2-ylidene; IPr = 1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene) with Grignard reagents. Examples of alkyl complexes possessing both four-coordinate and three-coordinate geometries are reported. The chloro complex [CoCl2(IMes) 2] adopts a pseudotetrahedral geometry displaying an S = 3/2 ground state, whereas the alkyl complex [Co(CH 3)2(IMes)2] adopts a square-planar geometry consistent with an S = 1/2 ground state. In contrast to [Co(CH3)2(IMes)2], [Co(CH2SiMe 3)2(IPr)] exhibits a three-coordinate trigonal-planar geometry displaying an S = 3/2 ground state. The catalytic efficacy of [CoCl2(IMes)2] in Kumada couplings is examined, as is the chemistry of the alkyl complexes toward CO. The structure and reactivity of these compounds is discussed in the context of C-C coupling reactions catalyzed by cobalt NHCs.

Ni/HZSM-5 catalyst preparation by deposition-precipitation. Part 2. Catalytic hydrodeoxygenation reactions of lignin model compounds in organic and aqueous systems

Barton,Carrier,Segura,Fierro,Park,Lamb,Escalona,Peretti

, p. 294 - 309 (2018)

Nickel metal supported on HZSM-5 (zeolite) is a promising catalyst for lignin depolymerization. In this work, the ability of catalysts prepared via deposition-precipitation (DP) to perform hydrodeoxygenation (HDO) on two lignin model compounds in organic and aqueous solvents was evaluated; guaiacol in dodecane and 2-phenoxy-1-phenylethanol (PPE) in aqueous solutions. All Ni/HZSM-5 catalysts were capable of guaiacol HDO into cyclohexane at 523 K. The role of the HZSM-5 acid sites was confirmed by comparison with Ni/SiO2 (inert support) which exhibited incomplete deoxygenation of guaiacol due to the inability to perform the cyclohexanol dehydration step. The catalyst prepared with 15 wt% Ni, a DP time of 16 h, and a calcination temperature of 673 K (Ni(15)/HZSM-5 DP16_Cal673), performed the guaiacol conversion with the greatest selectivity towards HDO products, with an intrinsic rate ratio (HDO rate to conversion rate) of 0.31, and 90% selectivity to cyclohexane. Catalytic activity and selectivity of Ni/HZSM-5 (15 wt%) in aqueous environments (water and 0.1 M NaOH solution) was confirmed using PPE reactions at 523 K. After 30 min reaction time in water, Ni/HZSM-5 exhibited ～100% conversion of PPE, and good yield of the desired products; ethylbenzene and phenol (～35% and 23% of initial carbon, respectively). Ni/HZSM-5 in NaOH solution resulted in significantly higher ring saturation compared to the Ni/HZSM-5 in water or the NaOH solution control.

Specific Inhibition of the Hydrogenolysis of Benzylic C?O Bonds Using Palladium Nanoparticles Supported on Nitrogen-Doped Carbon Nanofibers

Motoyama, Yukihiro,Morii, Koshi,Ishizuka, Shoya,Inomoto, Sou,Zhang, Zhenzhong,Yoon, Seong-Ho

, p. 505 - 509 (2018)

Palladium nanoparticles supported on 5 %-nitrogen-doped, herringbone-type carbon nanofibers (Pd/N-CNF-H), which are prepared by thermally decomposing [Pd2(dba)3?CHCl3] (dba=dibenzylideneacetone) in toluene in the presence of N-CNF-H, were found to be an efficient catalyst for the chemoselective hydrogenation of alkenyl and nitro moieties in benzyl-protected alcohols and carboxylic acid derivatives with high turnover frequencies: the hydrogenation reactions of these functional groups proceeded smoothly even at ambient temperature under atmospheric H2 pressure, and the benzyl protecting groups in the molecules remained intact. Moreover, the recovered Pd/N-CNF-H catalyst could be reused without loss of its catalytic activity or chemoselectivity. The Pd/N-CNF-H catalyst also acted as an effective hydrogenation catalyst for the reduction of aromatic ketones to the corresponding benzyl alcohol derivatives with good to high product selectivity.

Redox-active ligand-mediated oxidative addition and reductive elimination at square planar cobalt(III): Multielectron reactions for cross-coupling

Smith, Aubrey L.,Hardcastle, Kenneth I.,Soper, Jake D.

, p. 14358 - 14360 (2010)

Square planar cobalt(III) complexes with redox-active amidophenolate ligands are strong nucleophiles that react with alkyl halides, including CH 2Cl2, under gentle conditions to generate stable square pyramidal alkylcobalt(III) complexes. The net electrophilic addition reactions formally require 2e- oxidation of the metal fragment, but there is no change in metal oxidation state because the reaction proceeds with 1e - oxidation of each amidophenolate ligand. Although the four-coordinate complexes are very strong nucleophiles, they are mild outer-sphere reductants. Accordingly, addition of alkyl- or phenylzinc halides to the five-coordinate organometallic complexes regenerates the square planar starting materials and extrudes C-C coupling products. The net 2e- reductive elimination reaction also occurs without a oxidation state change at the cobalt(III) center. Together these reactions comprise a complete, well-defined cycle for cobalt Negishi-like cross-coupling of alkyl halides with organozinc reagents.

Supported palladium nanomaterials as catalysts for petroleum chemistry: 2. Kinetics and specific features of the mechanism of selective hydrogenation of phenylacetylene in the presence of carbon-supported palladium nanocatalyst

Berenblyum,Al-Wadhaf,Katsman

, p. 118 - 126 (2015)

The selective hydrogenation of phenylacetylene (PhA) into styrene (St) in the presence of a palladium nanocatalyst has been investigated. Salient features of this reaction have been revealed, such as independence of the PhA hydrogenation and St hydrogenat

Studies of the decomposition of the ethylene hydrophenylation catalyst TpRu(CO)(NCMe)Ph

Joslin, Evan E.,McKeown, Bradley A.,Cundari, Thomas R.,Gunnoe, T. Brent

, p. 289 - 293 (2017)

TpRu(CO)(NCMe)Ph is a catalyst for the conversion of benzene and ethylene to ethylbenzene. Previously, the formation of ethylbenzene has been shown to occur through a pathway that involves ethylene coordination to Ru, insertion of ethylene into the Ru–phe

Liquid-phase alkylation of benzene with ethylene over postsynthesized MCM-56 analogues

Zhang, Bin,Ji, Yongjun,Wang, Zhendong,Liu, Yueming,Sun, Hongmin,Yang, Weimin,Wu, Peng

, p. 103 - 110 (2012)

MCM-56 analogues were postsynthesized via a mild acid treatment technique from hydrothermally synthesized MCM-22 lamellar precursors with Si/Al ratios of 15-45. The physicochemical properties of MCM-56 were characterized by XRD, SEM, N2 adsorption, XPS, 29Si and 27Al MAS NMR, NH3-TPD and pyridine adsorption IR techniques. In comparison to MCM-22 with 3-dimensional MWW topology, the postsynthesized MCM-56 showed a broad X-ray diffraction of emerged 1 0 1 and 1 0 2 reflections and possessed a structural disorder along the layer stacking direction. Composed of partially delaminated MWW nanosheets, MCM-56 analogues had a larger external surface than MCM-22. The MCM-56 and MCM-22 catalysts were employed in the liquid-phase alkylation of benzene with ethylene. MCM-56 analogues exhibited a higher yield of ethylated benzenes and a higher catalytic stability than MCM-22, proving to serve as promising solid-acid catalysts for processing bulky molecules in petrochemical industry.

Reduced graphene oxide supported nickel-palladium alloy nanoparticles as a superior catalyst for the hydrogenation of alkenes and alkynes under ambient conditions

?etinkaya, Yasin,Metin, ?nder,Balci, Metin

, p. 28538 - 28542 (2016)

Addressed herein is the superior catalytic performance of reduced graphene oxide supported Ni30Pd70 alloy nanoparticles (rGO-Ni30Pd70) for the direct hydrogenation of alkenes and alkynes to alkanes, which surpasses the commercial Pd/C catalyst both in activity and stability. A variety of cyclic or aromatic alkenes and alkynes (a total of 17 examples) were rapidly reduced to the corresponding alkanes with high yields (>99%) via the presented direct hydrogenation protocol under ambient conditions. Compared to the commercially available Pd/C (10 wt%) catalyst, the rGO-Ni30Pd70 catalyst provided higher yields in shorter reaction times under the optimized conditions. Moreover, the rGO-Ni30Pd70 catalysts were more stable and durable than the commercial Pd/C catalysts by preserving their initial activity after five consecutive runs in the hydrogenation reactions.

Ketone Coupling on Reduced TiO2 (001) Surfaces: Evidence of Pinacol Formation

Pierce, Keith G.,Barteau, Mark A.

, p. 2405 - 2410 (1995)

Reductive coupling of acetone and acetophenone was investigated in temperature-programmed desorption (TPD) studies on both reduced (Ar(1+)-bombarded) and oxidized TiO2 (001) surfaces.The principal reaction product of either ketone on the reduced surface was a symmetric olefin with twice the carbon number of the reactant. 2,3-Diphenyl-2-butene comprised over 65percent of the volatile carbon-containing species desorbed from the reduced surface following acetophenone adsorption.The main side reactions which yielded products of the same carbon number as the reactants included deoxygenation to form olefins and deoxygenation plus hydrogenation to yield saturated species.The yield of reduction products was greatly diminished on the oxidized TiO2 (001) surface; the yield of 2,3-dimethyl-2-butene, the reductive coupling product of acetone, decreased 10-fold with respect to the yield from the reduced surface.This decrease in activity for reductive coupling is similar in scale to that observed for benzaldehyde coupling on the same surfaces, supporting the conclusion that both ketone and aldehyde coupling reactions occur at ensembles of Ti cations able to undergo a four-electron oxidation.Phenyl groups adjacent to the carbonyl carbon have the greatest effect on the carbonyl coupling reaction, giving significantly higher yield of the coupled olefin product.The observation of a small amount of the pinacol, 2,3-diphenyl-2,3-butanediol, during acetophenone TPD is the first direct evidence that the carbonyl coupling reaction on reduced TiO2 surfaces proceeds through a pinacolate intermediate, as it does for the McMurry reaction carried out in liquid-solid slurries.

Lanthanide assisted cross-coupling of aryl bromides with triethylaluminum

Shenglof, Margarita,Gelman, Dmitri,Molander, Gary A.,Blum, Jochanan

, p. 8593 - 8595 (2003)

Cerium trichloride, as well as some other lanthanide salts, promote the palladium-catalyzed cross-coupling of triethylaluminum with bromoarenes. The lanthanide compounds also increase the selectivity by diminishing the undesired hydrodebromination process

Photocatalytic properties of BiVO4 prepared by the co-precipitation method: Degradation of rhodamine B and possible reaction mechanisms under visible irradiation

Martínez-de la Cruz,Pérez, U.M. García

, p. 135 - 141 (2010)

Bismuth vanadate (BiVO4) was synthesized by the co-precipitation method at 200 °C. The photocatalytic activity of the oxide was tested for the photodegradation of rhodamine B under visible light irradiation. The analysis of the total organic carbon showed that the mineralization of rhodamine B over a BiVO4 photocatalyst (～40% after 100 h of irradiation) is feasible. In the same way, a gas chromatography analysis coupled with mass spectroscopy revealed the existence of organic intermediates during the photodegradation process such as ethylbenzene, o-xylene, m-xylene, and phthalic anhydride. The modification of variables such as dispersion pH, amount of dissolved O2, and irradiation source was studied in order to know the details about the photodegradation mechanism.

Blau,Willard

, p. 3330 (1953)

ELECTROCATALYTIC REDUCTION USING RANEY NICKEL.

Chiba,Okimoto,Nagai,Takata

, p. 719 - 723 (1983)

The Raney nickel catalyst was employed as a catalytic electrode in the electrohydrogenation of various unsaturated compounds, including ketones, aromatic aldehydes, Schiff's bases, oximes, nitriles, aromatic nitro compounds, olefins, and acetylenes. The hydrogen generated electrochemically was adsorbed and activated at the surface of the catalyst; it effectively hydrogenated these compounds, affording products which are very similar to those obtained in a normal catalytic hydrogenation with Raney nickel.

High Loading of Pd Nanoparticles by Interior Functionalization of MOFs for Heterogeneous Catalysis

Gole, Bappaditya,Sanyal, Udishnu,Banerjee, Rahul,Mukherjee, Partha Sarathi

, p. 2345 - 2354 (2016)

In this report, the issue related to nanoparticle (NP) agglomeration upon increasing their loading amount into metal-organic frameworks (MOFs) has been addressed by functionalization of MOFs with alkyne groups. The alkynophilicity of the Pd2+ (or other noble metals) ions has been utilized successfully for significant loading of Pd NPs into alkyne functionalized MOFs. It has been shown here that the size and loading amount of Pd NPs are highly dependent on the surface area and pore width of the MOFs. The loading amount of Pd NPs was increased monotonically without altering their size distribution on a particular MOF. Importantly, the distinct role of alkyne groups for Pd2+ stabilization has also been demonstrated by performing a control experiment considering a MOF without an alkyne moiety. The preparation of NPs involved two distinct steps viz. adsorption of metal ions inside MOFs and reduction of metal ions. Both of these steps were monitored by microscopic techniques. This report also demonstrates the applicability of Pd@MOF NPs as extremely efficient heterogeneous catalysts for Heck-coupling and hydrogenation reactions of aryl bromides or iodides and alkenes, respectively.

Size-controlled synthesis of MCM-49 zeolites and their application in liquid-phase alkylation of benzene with ethylene

Shi, Yanchun,Xing, Enhui,Xie, Wenhua,Zhang, Fengmei,Mu, Xuhong,Shu, Xingtian

, p. 13420 - 13429 (2015)

Size-controlled synthesis of MCM-49 zeolites was achieved via topology reconstruction from NaY zeolites with different sizes. SEM images showed that the sizes of the reconstructed H-MCM-49 zeolites were controlled by those of the parent NaY zeolites. Smal

Metal-ligand core-shell nanocomposite catalysts for the selective semihydrogenation of alkynes

Mitsudome, Takato,Takahashi, Yusuke,Ichikawa, Satoshi,Mizugaki, Tomoo,Jitsukawa, Koichiro,Kaneda, Kiyotomi

, p. 1481 - 1485 (2013)

Catalysts with a sheltered upbringing: Novel core-shell nanocomposite catalysts consisting of active metal nanoparticles encapsulated by macroligands have been prepared. They have Pd nanoparticles (PdNPs) as an active core and shell ligands having sulfoxide moieties coordinated to the PdNPs. The shell protects the catalyst from coordination by alkenes and allows the lead-free selective semihydrogenation of a wide range of alkynes without any additives (see scheme). Copyright

PHASE-TRANSFER CATALYSIS IN COBALT CATALYZED CARBONYLATION OF SECONDARY BENZYL HALIDES

Francalanci, F.,Foa, M.

, p. 59 - 70 (1982)

Application of the phase-transfer technique to the cobalt carbonyl-catalyzed carbonylation of secondary benzyl halides gives either monocarbonyl and double carbonyl insertion or coupling of organic halides as the major reaction, depending on the experimental conditions.Alcohols or ethers mainly give salts of carboxylic acids.Use of higher pressures of CO association with a hydrocarbon organic phase, favours coupling rather than carbonylation.A possible reaction mechanism is discussed.

Formal Cross-Coupling of Diaryl Ethers with Ammonia by Dual C(Ar)-O Bond Cleavages

Cao, Dawei,Zeng, Huiying,Li, Chao-Jun

, p. 8873 - 8878 (2018)

The conversion of renewable resources and inexpensive inorganic chemicals directly into higher value-added organic chemicals is becoming more and more important for our society's future sustainable development. Lignin, being the second most abundant organic carbon renewable resource on Earth, has been treated as waste in the pulp and paper industry. The 4-O-5 linkage diaryl ether bond is the strongest among the three types of ether linkages in lignins. Selective cleavage of this linkage can potentially generate smaller processable bio-based aromatic polymeric materials and compounds. Furthermore, there has been a long synthetic interest in coupling reactions with aryl ethers via C(Ar)-O bond cleavage, for example, for polyphenylene oxide (PPO) waste recycling. On the other hand, ammonia is a very inexpensive industrial inorganic chemical. Herein, we report a direct conversion of diaryl ethers and ammonia into aniline derivatives and arenes, providing a model for selective lignin 4-O-5 linkage modification and PPO recycling with inexpensive ammonia. Both symmetrical and unsymmetrical diaryl ethers were successfully cross-coupled with ammonia via dual C(Ar)-O bond cleavages, generating the corresponding cyclohexylanilines and arenes.

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Hession,Senior

, p. 163,164, 165 (1976)

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Cavitation chemistry of polychlorinated biphenyls: Decomposition mechanisms and rates

Zhang, Guangming,Hua, Inez

, p. 1529 - 1534 (2000)

Polychlorinated biphenyls (PCBs) are pollutants of environmental concern due to their widespread presence and persistence. The sonolytic destruction of aqueous polychlorinated biphenyls (PCBs) is reported in this article. The kinetics and transformation p

Pd@Pt Core-Shell Nanoparticles with Branched Dandelion-like Morphology as Highly Efficient Catalysts for Olefin Reduction

Datta, Kasibhatta Josena,Datta, Kasibhatta Kumara Ramanatha,Gawande, Manoj B.,Ranc, Vaclav,?épe, Klára,Malgras, Victor,Yamauchi, Yusuke,Varma, Rajender S.,Zboril, Radek

, p. 1577 - 1581 (2016)

A facile synthesis based on the addition of ascorbic acid to a mixture of Na2PdCl4, K2PtCl6, and Pluronic P123 results in highly branched core-shell nanoparticles (NPs) with a micro-mesoporous dandelion-like morphology comprising Pd core and Pt shell. The slow reduction kinetics associated with the use of ascorbic acid as a weak reductant and suitable Pd/Pt atomic ratio (1:1) play a principal role in the formation mechanism of such branched Pd@Pt core-shell NPs, which differs from the traditional seed-mediated growth. The catalyst efficiently achieves the reduction of a variety of olefins in good to excellent yields. Importantly, higher catalytic efficiency of dandelion-like Pd@Pt core-shell NPs was observed for the olefin reduction than commercially available Pt black, Pd NPs, and physically admixed Pt black and Pd NPs. This superior catalytic behavior is not only due to larger surface area and synergistic effects but also to the unique micro-mesoporous structure with significant contribution of mesopores with sizes of several tens of nanometers.

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Kuivila et al.

, p. 3584 (1962)

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Flash vacuum pyrolysis over magnesium. Part 1 - Pyrolysis of benzylic, other aryl/alkyl and aliphatic halides

Aitken, R. Alan,Hodgson, Philip K.G.,Morrison, John J.,Oyewale, Adebayo O.

, p. 402 - 415 (2002)

Flash vacuum pyrolysis over a bed of freshly sublimed magnesium on glass wool results in efficient coupling of benzyl halides to give the corresponding bibenzyls. Where an ortho halogen substituent is present further dehalogenation gives some dihydroanthracene and anthracene. Efficient coupling is also observed for halomethylnaphthalenes and halodiphenylmethanes while chlorotriphenylmethane gives 4,4′-bis(diphenylmethyl)biphenyl. By using α,α′-dihalo-o-xylenes, benzocyclobutenes are obtained in good yield, while the isomeric α,α′-dihalo-p-xylenes give a range of high thermal stability polymers by polymerisation of the initially formed p-xylylenes. Other haloalkylbenzenes undergo largely dehydrohalogenation where this is possible, in some cases resulting in cyclisation. Deoxygenation is also observed with haloalkyl phenyl ketones to give phenylalkynes as well as other products. With simple alkyl halides there is efficient elimination of HCl or HBr to give alkenes. For aliphatic dihalides this also occurs to give dienes but there is also cyclisation to give cycloalkanes and dehalogenation with hydrogen atom transfer to give alkenes in some cases. For 5-bromopent-1-ene the products are those expected from a radical pathway but for 6-bromohex-1-ene they are clearly not. For 2,2-dichloropropane and 1,1-dichloropropane elimination of HCl occurs but for 1,1-dichlorobutane, -pentane and -hexane partial hydrolysis followed by elimination of HCl gives E, E-, E,Z- and Z,Z- isomers of the dialk-1-enyl ethers and fully assigned 13C NMR data are presented for these. With 6-chlorohex-1-yne and 7-chlorohept-1-yne there is cyclisation to give methylenecycloalkanes and -cycloalkynes. The behaviour of 1,2-dibromocyclohexane and 1,2-dichlorocyclooctane under these conditions is also examined. Various pieces of evidence are presented that suggest that these processes do not involve generation of free gas-phase radicals but rather surface-adsorbed organometallic species.

Facile access to: N -substituted anilines via dehydrogenative aromatization catalysis over supported gold-palladium bimetallic nanoparticles

Taniguchi, Kento,Jin, Xiongjie,Yamaguchi, Kazuya,Mizuno, Noritaka

, p. 3929 - 3937 (2016)

N-Substituted anilines are widely utilized important compounds, and the development of their diverse synthetic procedures is of great significance. Herein, we have successfully developed a widely applicable powerful catalytic route to N-substituted anilines. In the presence of a gold-palladium alloy nanoparticle catalyst (Au-Pd/Al2O3) and styrene, various kinds of structurally diverse N-substituted anilines (twenty three examples) could be synthesized starting from cyclohexanones and amines (including aliphatic primary and secondary amines and anilines). The catalytic performance was strongly influenced by the nature of the catalyst. A supported gold catalyst (Au/Al2O3) was completely inactive for the present transformation. Although a supported palladium catalyst (Pd/Al2O3) gave the desired N-substituted anilines to some extent, the performance was inferior to that of Au-Pd/Al2O3. The catalytic activity of the palladium species in Au-Pd/Al2O3 was at least ca. three times higher than that in Pd/Al2O3. Moreover, the performance of Au-Pd/Al2O3 was superior to that of a physical mixture of Au/Al2O3 and Pd/Al2O3. Thus, palladium was intrinsically effective for the present transformation (dehydrogenative aromatization) and its performance was improved by alloying with gold. The present transformation proceeds through a sequence of the dehydrative condensation of cyclohexanones and amines to produce enamines (or ketimines), followed by the dehydrogenative aromatization to produce the corresponding N-substituted anilines. In the aromatization step, styrene could act as an effective hydrogen acceptor to selectively produce the desired N-substituted anilines without catalyzing the disproportionation of the enamine intermediates. The observed catalysis using Au-Pd/Al2O3 was truly heterogeneous in nature, and Au-Pd/Al2O3 could be reused.

Selective hydrogenolysis of lignin and model compounds to monophenols over AuPd/CeO2

Gao, Xiaoqing,Zhu, Shanhui,Li, Yongwang

, p. 69 - 76 (2019)

The mild depolymerization of lignin into aromatic monomer is a grand challenge owing to the various aryl ether C–O bonds, particularly for the most abundant β-O-4, α-O-4 and 4-O-5 linkages. Rod-shaped CeO2 supported AuPd bimetallic catalysts fabricated by sol-immobilization method presented robust alloy structure, as evidenced by TEM, XPS, UV–vis, and CO-DRIFTS. For the hydrogenolysis of C–O bond model compound with formic acid, Au1Pd1/CeO2 showed about 23.5 and 6 folds increase in activity compared with its monometallic counterparts Au/CeO2 and Pd/CeO2, respectively. The outstanding performance was mainly ascribed to the increased adsorption ability of electron-deficient Pd for aromatic C–O bond. Additionally, formic acid-mediated Au1Pd1/CeO2 has efficiently performed hydrogenolysis of real lignin into a variety of valuable monophenols, achieving 44.1% yield at low temperature.

Recyclable cobalt(0) nanoparticle catalysts for hydrogenations

Büschelberger, Philipp,Reyes-Rodriguez, Efrain,Sch?ttle, Christian,Treptow, Jens,Feldmann, Claus,Jacobi Von Wangelin, Axel,Wolf, Robert

, p. 2648 - 2653 (2018)

The search for new hydrogenation catalysts that replace noble metals is largely driven by sustainability concerns and the distinct mechanistic features of 3d transition metals. Several combinations of cobalt precursors and specific ligands in the presence of reductants or under high-thermal conditions were reported to provide active hydrogenation catalysts. This study reports a new method of preparation of small, monodisperse Co(0) nanoparticles (3-4 nm) from the reduction of commercial CoCl2 in the absence of ligands or surfactants. High catalytic activity was observed in hydrogenations of alkenes, alkynes, imines, and heteroarenes (2-20 bar H2). The magnetic properties enabled catalyst separation and multiple recyclings.

Metal-organic frameworks (MOFs) as heterogeneous catalysts for the chemoselective reduction of carbon-carbon multiple bonds with hydrazine

Dhakshinamoorthy, Amarajothi,Alvaro, Mercedes,Garcia, Hermenegildo

, p. 2271 - 2276 (2009)

The as-synthesized metal-organic frameworks (MOFs), particularly that based on aluminium coordinated with benzenedicarboxylic acid, constitute selective catalysts for the reduction of carbon-carbon multiple bonds in alkenes, alkynes and α,β-unsaturated esters with hydrazine hydrate in acetonitrile under mild conditions. The present protocol enjoys advantages such as convenient reaction conditions and benign, reusable and cost effective catalyst.

Synthesis of bipyridine-stabilized rhodium nanoparticles in non-aqueous ionic liquids: A new efficient approach for arene hydrogenation with nanocatalysts

Leger, Bastien,Denicourt-Nowicki, Audrey,Roucoux, Alain,Olivier-Bourbigou, Helene

, p. 153 - 159 (2008)

A new approach to stabilize metal nanoparticles with polynitrogen ligands in ionic liquids (ILs) is described. Zerovalent metal nanospecies in the size range of 2.0 nm were easily prepared in various ionic liquids by chemical reduction of a rhodium salt with an excess amount of sodium borohydride (NaBH4) and efficiently stabilized by 2,2′-bipyridine. The influence of the bipyridine ratio in various ILsaccording to the nature of the cation-anion association was investigated. These nanocatalysts were evaluated in the hydrogenation of aromatic compounds in ILs under various catalytic conditions (P=1-40 bar, T=20-80 °C).

Effect of immobilized carbon nanoparticles on the activity of zeolites in the oxidative dehydrogenation of 4-vinylcyclohexene and ethylbenzene to styrene

Alimardanov,Alieva,Abasov,Abbasov,Kuliev

, p. 97 - 104 (2012)

The results of studies on the oxidative dehydrogenation of 4-vinylcyclohexene to ethylbenzene and styrene and ethylbenzene to styrene on nanocomposite systems prepared by the immobilization of carbon nanoparticles on the H forms of zeolites and the modifi

The preparation of silica entrapped homogeneous hydrogenation catalysts by conventional and ionic liquid mediated sol-gel routes

Craythorne, Steven J.,Crozier, Alan R.,Lorenzini, Fabio,Marr, Andrew C.,Marr, Patricia C.

, p. 3518 - 3521 (2005)

[RhCl(PPh3)3] has been entrapped inside silica matrices by two methods: a conventional sol-gel synthesis in ethanol/water and a new route performed in an ionic liquid. The activity of these heterogenised catalysts has been tested for the hydrogenation of styrene. The catalyst prepared in an ionic liquid was found to be more active and have low Rh leaching.

Continuous hydrogenation of organic compounds in supercritical fluids

Hitzler, Martin G.,Poliakoff, Martyn

, p. 1667 - 1668 (1997)

A small flow reactor (5 ml volume) is used for continuous hydrogenation in supercritical CO2 or propane with polysiloxane-supported noble metal catalysts; a wide range of organic functionalities can be hydrogenated with good throughput (up to 1200 ml h-1 in favourable cases) and the various parameters (temperature, pressure, concentration of H2, etc.) can be controlled independently to optimise the selectivity for a particular product.

Metal-Organic Frameworks Stabilize Solution-Inaccessible Cobalt Catalysts for Highly Efficient Broad-Scope Organic Transformations

Zhang, Teng,Manna, Kuntal,Lin, Wenbin

, p. 3241 - 3249 (2016)

New and active earth-abundant metal catalysts are critically needed to replace precious metal-based catalysts for sustainable production of commodity and fine chemicals. We report here the design of highly robust, active, and reusable cobalt-bipyridine- and cobalt-phenanthroline-based metal-organic framework (MOF) catalysts for alkene hydrogenation and hydroboration, aldehyde/ketone hydroboration, and arene C-H borylation. In alkene hydrogenation, the MOF catalysts tolerated a variety of functional groups and displayed unprecedentedly high turnover numbers of ～2.5 × 106 and turnover frequencies of ～1.1 × 105 h-1. Structural, computational, and spectroscopic studies show that site isolation of the highly reactive (bpy)Co(THF)2 species in the MOFs prevents intermolecular deactivation and stabilizes solution-inaccessible catalysts for broad-scope organic transformations. Computational, spectroscopic, and kinetic evidence further support a hitherto unknown (bpy?-)CoI(THF)2 ground state that coordinates to alkene and dihydrogen and then undergoing σ-complex-assisted metathesis to form (bpy)Co(alkyl)(H). Reductive elimination of alkane followed by alkene binding completes the catalytic cycle. MOFs thus provide a novel platform for discovering new base-metal molecular catalysts and exhibit enormous potential in sustainable chemical catalysis.

Platinum(II) complexes incorporating racemic and optically active 1-alkyl-3-phospholene P-ligands: Synthesis, stereostructure, NMR properties and catalytic activity

Bagi, Péter,Kovács, Tamara,Szilvási, Tibor,Pongrácz, Péter,Kollár, László,Drahos, László,Fogassy, Elemér,Keglevich, Gy?rgy

, p. 306 - 313 (2014)

Three 1-alkyl-3-phospholene 1-oxides, such as the P-ethyl, P-isobutyl and P-isopentyl derivative were prepared in racemic and enantiopure forms. After deoxygenation, the cyclic phosphines were converted to the corresponding phosphineeboranes and phosphine

(Pyridyl)benzoazole palladium(II) complexes as homogeneous catalysts in hydrogenation of alkenes and alkynes

Ojwach, Stephen O.,Ogweno, Aloice O.,Akerman, Matthew P.

, p. 5069 - 5078 (2016)

Reactions of 2-(2-pyridyl)benzimidazole (L1), 2-(2-pyridyl)benzothiazole (L2) and 2-(2-pyridyl)benzoxazole (L3) with either [PdCl2(NCMe)2] or [PdClMe(COD)] produced complexes [(PdCl2(L1)] (1), [(PdCl2(L2)] (2), [(PdCl2(L3)] (3) and [(PdClMe(L1)] (4) in good yields. Treatment of 1 with PPh3 gave the cationic complex [(Pd(L1)ClPPh3]Cl (5), while reactions of 4 with one equiv. of PPh3 and NaBAr4 (Ar = 3,5-(CF3)2C6H3) produced the cationic complex [(Pd(L1)MePPh3]BAr4 (6). Single-crystal X-ray analysis has been used to elucidate the structure of complex 6. The complexes formed active catalysts in hydrogenation reactions of alkenes and alkynes. Hydrogenation of terminal alkenes was accompanied by isomerization to the internal isomers, while alkyne reactions involved a two-step process producing alkenes and the respective alkanes. While the kinetics data and formation of inactive palladium nanoparticles support the homogeneous nature of the active species, mercury drop experiments indicated a possible role of the nanoparticles in the re-generation of the active species.

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Jones,Schmeltz

, p. 645 (1969)

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Phosphido- and Amidozirconocene Cation-Based Frustrated Lewis Pair Chemistry

Normand, Adrien T.,Daniliuc, Constantin G.,Wibbeling, Birgit,Kehr, Gerald,Le Gendre, Pierre,Erker, Gerhard

, p. 10796 - 10808 (2015)

Methyl abstraction from neutral [Cp2ZrMe(ERR)] complexes 1 (E = N, P; R, R'; = alkyl, aryl) with either B(C6F5)3 or [Ph3C][B(C6F5)4] results in the formation of [Cp2Zr(ERR′)][X] complexes 2 (X- = MeB(C6F5)3-, B(C6F5)4-). The X-ray structure of amido complexes [Cp2Zr(NPh2)][MeB(C6F5)3] (2d) and [Cp2Zr(NtBuAr)][B(C6F5)4] (2e′, Ar = 3,5-C6H3(CH3)2) is reported, showing a sterically dependent Zr/N' interaction. Complexes 2 catalyze the hydrogenation of electron-rich olefins and alkynes under mild conditions (room temperature, 1.5 bar H2). Complex 2e binds CO2, giving [Cp2Zr(CO2)(NtBuAr)]2[MeB(C6F5)3]2 (3e). Amido complex 2d reacts with benzaldehyde yielding [Cp2Zr(OCH2Ph)((OC)PhNPh2)][MeB(C6F5)3] (7d). Phosphido complex [Cp2Zr(PCy2)][MeB(C6F5)3] (2a) reacts with diphenylacetylene to yield frustrated Lewis pair [Cp2Zr(PhCCPh)(PCy2)][MeB(C6F5)3] (8a) which further reacts with a range of carbonyl substrates.

Supported palladium nanomaterials as catalysts for petroleum chemistry: 1. Specifics of palladium diacetate reduction with hydrogen on silica gel in catalyst synthesis

Berenblyum,Al-Wadhaf,Katsman,Shamsiev,Koroleva

, p. 105 - 110 (2014)

The reduction reaction of Pd(II) diacetate, a precursor in nanocatalyst synthesis, with molecular hydrogen on silica gel has been studied. A kinetic model involving the autocatalytic mechanism of Pd(II) reduction to Pd(0) and adequately describing the exp

Selectivity difference between hydrogenation of acetophenone over CNTs and ACs supported Pd catalysts

Xiang, Yi-Zhi,Lv, Yong-An,Xu, Tie-Yong,Li, Xiao-Nian,Wang, Jian-Guo

, p. 70 - 75 (2011)

Selectivity difference between hydrogenation of acetophenone over carbon nanotubes (CNTs) and commercial activated carbons (ACs) supported Pd catalysts has been investigated. The selectivity of α-phenylethanol over the Pd/CNTs catalyst is significantly hi

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Ohkubo et al.

, p. 2807,2809, 2811 (1978)

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Synthesis, characterization and catalytic function of a B 12-hyperbranched polymer

Tahara, Keishiro,Shimakoshi, Hisashi,Tanaka, Akihiro,Hisaeda, Yoshio

, p. 3035 - 3042 (2010)

A new hybrid catalyst composed of a vitamin B12 derivative and a hyperbranched polymer (HBP) was synthesized and characterized by UV-vis and ESR spectroscopy as well as AFM. The B12-HBP showed good properties as a homogenous catalyst

Visible light-driven selective hydrogenation of unsaturated aromatics in an aqueous solution by direct photocatalysis of Au nanoparticles

Huang, Yiming,Liu, Zhe,Gao, Guoping,Xiao, Qi,Martens, Wayde,Du, Aijun,Sarina, Sarina,Guo, Cheng,Zhu, Huaiyong

, p. 726 - 734 (2018)

Selective hydrogenation of various chemical bonds, such as CC, CC, CO, NO, and CN, is efficiently driven by visible light over a supported gold nanoparticle (AuNP) photocatalyst under mild reaction conditions. The reaction system exhibits high substituent tolerance and tunable selectivity by light wavelength. Density functional theory (DFT) calculations demonstrated a strong chemisorption between the reactant molecule and metal resulting in hybridized orbitals. It is proposed that direct photoexcitation between hybridized orbitals is the main driving force of the hydrogenation reaction. The hydrogenation pathway is investigated by the isotope tracking technique. We revealed the cooperation of water and formic acid (FA) as a hydrogen source and the hydrogenation route through Au-H species on the AuNP surface.

Hydrogenation of arenes over catalysts that combine a metal phase and a grafted metal complex: Role of the single-site catalyst

Bianchini, Claudio,Dal Santo, Vladimiro,Meli, Andrea,Moneti, Simonetta,Moreno, Marta,Oberhauser, Werner,Psaro, Rinaldo,Sordelli, Laura,Vizza, Francesco

, p. 2636 - 2639 (2003)

Cooperating catalysts: The combined single-site/dispersed-metal catalyst [Rh(cod)(sulphos)]-Pd0/SiO2 (cod= cyclooctadiene; sulphos = -O3S(C6H4)CH2C(CH2 PPh2)3) is more efficient than the dispersed-metal catalyst Pd0/SiO2 for the hydrogenation of arenes to cycloalkanes. The grafted rhodium moieties and the palladium particles in [Rh(cod)(sulphos)]-Pd0/SiO2 cooperate to speed up the hydrogenation of arenes (see scheme).

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Reggel et al.

, p. 1136,1138 (1958)

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Magnetically recoverable supported ruthenium catalyst for hydrogenation of alkynes and transfer hydrogenation of carbonyl compounds

Baruwati, Babita,Polshettiwar, Vivek,Varma, Rajender S.

, p. 1215 - 1218 (2009)

A ruthenium (Ru) catalyst supported on magnetic nanoparticles (NiFe2O4) has been successfully synthesized and used for hydrogenation of alkynes at room temperature as well as transfer hydrogenation of a number of carbonyl compounds under microwave irradiation conditions. The catalyst shows excellent selectivity toward the desired products with very high yield even after five repeated uses.

Exploiting the radical reactivity of diazaphosphinanes in hydrodehalogenations and cascade cyclizations

Cheng, Jin-Pei,Yang, Jin-Dong,Zhang, Jingjing

, p. 4786 - 4790 (2020)

The remarkable reducibility of diazaphosphinanes has been extensively applied in various hydrogenations, based on and yet limited by their well-known hydridic reactivity. Here we exploited their unprecedented radical reactivity to implement hydrodehalogenations and cascade cyclizations originally inaccessible by hydride transfer. These reactions feature a broad substrate scope, high efficiency and simplicity of manipulation. Mechanistic studies suggested a radical chain process in which a phosphinyl radical is generated in a catalytic cycle via hydrogen-atom transfer from diazaphosphinanes. The radical reactivity of diazaphosphinanes disclosed here differs from their well-established hydridic reactivity, and hence, opens a new avenue for diazaphosphinane applications in organic syntheses.

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Dow

, p. 1267 (1942)

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One-pot synthesis of ethylbenzene/1-phenylethanol and γ-butyrolactone from simultaneous acetophenone hydrogenation and 1,4-butanediol dehydrogenation over copper based catalysts: Effects of the support

Kannapu, Hari Prasad Reddy,Suh, Young-Woong,Narani, Anand,Vaddeboina, Veeralakshmi,Burri, David Raju,Kamaraju Seetha, Rama Rao

, p. 35346 - 35356 (2017)

The effect of the support in the simultaneous hydrogenation of acetophenone and dehydrogenation of 1,4-butanediol was studied using supported (MgO, γ-Al2O3, MgO-Al2O3 and SiO2) copper (10 wt%) catalys

Ligand effect on the catalytic activity of ruthenium nanoparticles in ionic liquids

Salas, Gorka,Campbell, Paul S.,Santini, Catherine C.,Philippot, Karine,Costa Gomes, Margarida F.,Pádua, Agílio A.H.

, p. 13919 - 13926 (2012)

Suspensions of small sized (1-2.5 nm) ruthenium nanoparticles (RuNPs) have been obtained by decomposition, under H2, of (η4-1,5- cyclooctadiene)(η6-1,3,5-cyclooctatriene)ruthenium(0), [Ru(COD)(COT)], in the ionic liquid 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, [C1C4Im][NTf 2], and in the presence of different compounds acting as ligands: C8H17NH2, PPhH2, PPh2H and H2O. Previous and new liquid NMR experiments showed that the ligands are coordinated or in the proximity to the surface of the RuNPs. Herein is reported how the ligand affects the catalytic performance (activity and selectivity) compared to a ligand-free system of RuNPs, when RuNPs in [C 1C4Im][NTf2] are used as catalysts for the hydrogenation of various unsaturated compounds (1,3-cyclohexadiene, limonene and styrene). It has been observed that σ-donor ligands increase the activity of the nanoparticles, contrarily to π-acceptor ones.

A novel and efficient N-doping carbon supported cobalt catalyst derived from the fermentation broth solid waste for the hydrogenation of ketones via Meerwein–Ponndorf–Verley reaction

Chen, Yuxin,He, Runxia,Liu, Quansheng,Yao, Xuefeng,Zhou, Huacong

, (2021/12/10)

Most of the non-noble metal catalysts used for the Meerwein–Ponndorf–Verley (MPV) reaction of carbonyl compounds rely on the additional alkaline additives during preparation to achieve high efficiency. To solve this problem, in this work, we prepared a novel N-doped carbon supported cobalt catalyst (Co@CN), in which the carriers were derived from the nitrogen-rich organic waste, i.e., oxytetracycline fermentation residue (OFR, obtained from oxytetracycline refining workshop). No additional nitrogen sources were used during preparation. The results showed that inherent nitrogen in OFR could provide N-containing basic sites, and formed Co-N structures via coordinating with cobalt. The Co-N sites together with the coexisting Co(0) cooperated to catalyze the conversion of ethyl levulinate (EL) to γ-valerolactone (GVL) by MPV reaction. Co(0) dominated the activation of H in isopropanol, while Co-N dominated the formation of the six-membered ring transition state.

Fabricating nickel phyllosilicate-like nanosheets to prepare a defect-rich catalyst for the one-pot conversion of lignin into hydrocarbons under mild conditions

Cao, Meifang,Chen, Bo,He, Chengzhi,Ouyang, Xinping,Qian, Yong,Qiu, Xueqing

supporting information, p. 846 - 857 (2022/02/09)

The one-pot conversion of lignin biomass into high-grade hydrocarbon biofuels via catalytic hydrodeoxygenation (HDO) holds significant promise for renewable energy. A great challenge for this route involves developing efficient non-noble metal catalysts to obtain a high yield of hydrocarbons under relatively mild conditions. Herein, a high-performance catalyst has been prepared via the in situ reduction of Ni phyllosilicate-like nanosheets (Ni-PS) synthesized by a reduction-oxidation strategy at room temperature. The Ni-PS precursors are partly converted into Ni0 nanoparticles by in situ reduction and the rest remain as supports. The Si-containing supports are found to have strong interactions with the nickel species, hindering the aggregation of Ni0 particles and minimizing the Ni0 particle size. The catalyst contains abundant surface defects, weak Lewis acid sites and highly dispersed Ni0 particles. The catalyst exhibits excellent catalytic activity towards the depolymerization and HDO of the lignin model compound, 2-phenylethyl phenyl ether (PPE), and the enzymatic hydrolysis of lignin under mild conditions, with 98.3% cycloalkane yield for the HDO of PPE under 3 MPa H2 pressure at 160 °C and 40.4% hydrocarbon yield for that of lignin under 3 MPa H2 pressure at 240 °C, and its catalytic activity can compete with reported noble metal catalysts.

One-step conversion of lignin-derived alkylphenols to light arenes by co-breaking of C-O and C-C bonds

Di, Yali,Li, Guangyu,Li, Zhiqin,Liu, Weiwei,Qiu, Zegang,Ren, Xiaoxiong,Wang, Ying

supporting information, p. 2710 - 2721 (2022/02/21)

The conversion of lignin-derived alkylphenols to light arenes by a one-step reaction is still a challenge. A 'shortcut' route to transform alkylphenols via the co-breaking of C-O and C-C bonds is presented in this paper. The catalytic transformation of 4-ethylphenol in the presence of H2 was used to test the breaking of C-O and C-C bonds. It was found that the conversion of 4-ethylphenol was nearly 100%, and the main products were light arenes (benzene and toluene) and ethylbenzene under the catalysis of Cr2O3/Al2O3. The conversion of 4-ethylphenol and the selectivity of the products were significantly influenced by the reaction temperature. The selectivity for light arenes reached 55.7% and the selectivity for overall arenes was as high as 84.0% under suitable reaction conditions. Such results confirmed that the co-breaking of the C-O and C-C bonds of 4-ethylphenol on a single catalyst by one step was achieved with high efficiency. The adsorption configuration of the 4-ethylphenol molecule on the catalyst played an important role in the breaking of the C-O and C-C bonds. Two special adsorption configurations of 4-ethylphenol, including a parallel adsorption and a vertical adsorption, might exist in the reaction process, as revealed by DFT calculations. They were related to the breaking of C-O and C-C bonds, respectively. A path for the hydrogenation reaction of 4-ethylphenol on Cr2O3/Al2O3 was proposed. Furthermore, the co-breaking of the C-O and C-C bonds was also achieved in the hydrogenation reactions of several alkylphenols. This journal is

MOF-derived Ru@ZIF-8 catalyst with the extremely low metal Ru loading for selective hydrogenolysis of C–O bonds in lignin model compounds under mild conditions

Cao, Jing-Pei,Jiang, Wei,Xie, Jin-Xuan,Zhang, Chuang,Zhang, Jian-Li,Zhao, Liang,Zhao, Xiao-Yan,Zhao, Yun-Peng,Zhu, Chen

, p. 488 - 496 (2022/02/07)

Lignin hydrogenolysis to produce chemicals and biofuels is a challenge due to the stable C–O ether bond structure. Metal–organic framework (MOF) materials with excellent structural and chemical versatility have received widespread attention. Herein, a highly dispersed Ru metal anchored in functionalised ZIF-8 was fabricated by a general host–guest and reduction strategy. The Ru@ZIF-8 catalyst with a high specific surface area could efficiently promote the C–O bond cleavage of a variety of lignin model compounds under mild conditions. Compared with previous studies, the extremely low metal Ru loading in the Ru@ZIF-8 catalyst achieved a relatively higher activity. The introduction of Ru metal not only improved the dispersion of Zn metal, but also enhanced the electron density on the Zn surface, suggesting a high catalytic performance. It was more conducive for the Ru@ZIF-8 catalyst to exhibit the C–O bond cleavage activity when in the presence of both H2 and isopropanol. An investigation of the mechanism revealed that the direct hydrogenolysis of benzyl phenyl ether was the main reaction pathway.

Rhodium-catalyzed anti-Markovnikov hydrosilylation of alkenes

Liu, Wei,Lu, Wenkui,Wu, Xiaoyu,Yang, Liqun,Zhang, Zhaoguo

supporting information, (2022/02/01)

Rh-catalyzed anti-Markovnikov hydrosilylation of terminal alkenes and tertiary silanes using readily-available PPh3 as the ligand was reported. This method facilitated the effective synthesis of alkylsilanes with a wide substrate scope and high