111-66-0Relevant articles and documents
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Seyferth,Weiner
, p. 1395 (1959)
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Photocatalytic properties of new cyclopentadienyl and indenyl rhodium(I) carbonyl complexes with water-soluble 1,3,5-triaza-7-phosphaadamantane (PTA) and tris(2-cyanoethyl)phosphine
Smoleński, Piotr
, p. 3867 - 3872 (2011)
Reactions of [(η5-R)Rh(CO)2] (R = cp, ind) with water-soluble phosphines (L = 1,3,5-triaza-7-phosphaadamantane and tris(2-cyanoethyl)phosphine) give the new rhodium(I) complexes of the types [Rh(η5-cp)(CO)(PTA)] (1), [Rh(η5-cp)(CO)(P(CH 2CH2CN)3)] (2), [Rh(η5-ind)(CO) (PTA)] (3) and [Rh(η5-ind)(CO)(P(CH2CH 2CN)3)] (4) in isolated yields of 52-75%. All these compounds have been fully characterized by IR, 1H, 31P{1H} and 13C{1H} NMR, FAB-MS spectroscopies and elemental analyses. Reactivity for the substitution of phosphine is greater for [(η5-ind)Rh(CO)(L)] comparing to [(η5-cp)Rh(CO)(L)] because of a flexibility of the indenyl ligand to undergo facile η5-η3 coordinative isomerizations. The obtained complexes are active catalyst precursors for the dehydrogenation of propan-2-ol, octane and cyclooctane under photoassisted conditions without any organic hydrogen transfer acceptors, giving TOFs of 26-56 using 3 as precatalyst.
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Hata,Watanabe
, p. 8450 (1973)
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Influence of elevated temperature and pressure on the chromium-catalysed tetramerisation of ethylene
Kuhlmann, Sven,Dixon, John T.,Haumann, Marco,Morgan, David H.,Ofili, Jimmy,Spuhl, Oliver,Taccardi, Nicola,Wasserscheid, Peter
, p. 1200 - 1206 (2006)
A catalyst system comprising a diphenylphosphineamine (PNP) ligand, chromium(III) acetylacetonate and a methylaluminoxane-based activator was studied for the selective tetramerisation of ethylene. The reaction was investigated over a broad temperature and pressure range and the resulting product mixture was interpreted in the light of the recently published, enlarged metallacycle mechanism. Vapour-liquid equilibrium (VLE) data were calculated for the binary ethylene-cyclohexane mixture over the relevant temperature and pressure ranges to deconvolute the influence of ethylene concentration and temperature. Good agreement of the experimental data with the proposed mechanism was found. Enlargement of the metallacycloheptane ring by insertion of ethylene was found to be dependent on the ethylene concentration, albeit to a lesser extent than assumed. The 1-octene selectivity, which reaches a maximum of 72-74 mass %, thus seems to be primarily dependent on the temperature. The formation of the cyclic side products methyl- and methylenecyclopentane was in effect independent of the ethylene concentration. This is in good accordance with the proposed mechanism, since it indicates that the formation of the products occurs via rearrangement of a metallacycle intermediate.
Synthesis of Pincer Hydrido Ruthenium Olefin Complexes for Catalytic Alkane Dehydrogenation
Zhang, Yuxuan,Fang, Huaquan,Yao, Wubing,Leng, Xuebing,Huang, Zheng
, p. 181 - 188 (2016)
A series of new hydrido Ru(II) olefin complexes supported by isopropyl-substituted pincer ligands have been synthesized and characterized. These complexes are thermally robust and active for catalytic transfer and acceptorless alkane dehydrogenation. Notably, the alkane dehydrogenation catalysts are tolerant of a number of polar functional species.
Semihydrogenation of Alkynes Catalyzed by a Pyridone Borane Complex: Frustrated Lewis Pair Reactivity and Boron–Ligand Cooperation in Concert
Wech, Felix,Hasenbeck, Max,Gellrich, Urs
, p. 13445 - 13450 (2020)
The metal-free cis selective hydrogenation of alkynes catalyzed by a boroxypyridine is reported. A variety of internal alkynes are hydrogenated at 80 °C under 5 bar H2 with good yields and stereoselectivity. Furthermore, the catalyst described herein enables the first metal-free semihydrogenation of terminal alkynes. Mechanistic investigations, substantiated by DFT computations, reveal that the mode of action by which the boroxypyridine activates H2 is reminiscent of the reactivity of an intramolecular frustrated Lewis pair. However, it is the change in the coordination mode of the boroxypyridine upon H2 activation that allows the dissociation of the formed pyridone borane complex and subsequent hydroboration of an alkyne. This change in the coordination mode upon bond activation is described by the term boron-ligand cooperation.
A NEW METHOD FOR THE in Situ GENERATION OF Cp2Zr(H)Cl (SCHWARTZ' REAGENT)
Lipshutz, Bruce H.,Keil, Robert,Ellsworth, Edmund L.
, p. 7257 - 7260 (1990)
Treatment of Cp2ZrCl2 with LiEt3BH in THF leads to formation of Cp2Zr(H)Cl.Subsequently introduced terminal acetylenes undergo hydrozirconation without compromising acid-sensitive functionality present in the alkyne.
Switching a catalyst system from ethene polymerization to ethene trimerization with a hemilabile ancillary ligand
Deckers, Patrick J. W.,Hessen, Bart,Teuben, Jan H.
, p. 2516 - 2519 (2001)
A drastic ligand effect was observed in the catalytic ethene conversion by the substituted mono(cyclopentadienyl)titaniumtrichloride/methylalumoxane (MAO) catalysts shown. The catalyst with R = Me produces polyethene, whereas the catalyst with R = Ph selectively trimerizes ethene to 1-hexene. This switch in catalyst performance appears to be the result of a hemilabile behavior of the cyclopentadienyl ligand with the pendant arene group, involving reversible coordination of the arene moiety.
CHEMISTRY OF ALKALI METAL TETRACARBONYLFERRATES. SYNTHESIS OF AMINES AND DEHALOGENATION REACTIONS BY A POLYMER SUPPORTED IRON CARBONYL COMPLEX
Boldrini, Gian Paolo,Cainelli, Gianfranco,Umani-Ronchi, Achille
, p. 195 - 198 (1983)
The polymer-supported HFe(CO)4- can be easily prepared from potassium tetracarbonylhydridoferrate by an ion-exchange process with an ion-exchange resin (Amberlyst A 26) in its chloride form.It selectively reduces nitroarenes to amines, and reacts with 1,2-dibromoalkanes to give alkenes in good to excellent yields.
Kinetics of Reductions of Substituted Benzaldehydes with B-Alkyl-9-borabicyclononane (9-BBN)
Midland, M. Mark,Zderic, Stephen A.
, p. 525 - 528 (1982)
Second-order rate constants for the reaction of B-n-octyl-9-BBN with para-substituted benzaldehydes were obtained.Electron-withdrawing groups on the benzaldehyde increase the rate of reduction.The rate constants correlate with ?+ (ρ +1.03).Relative rates for reduction of para-substituted benzaldehydes with B-3-pinanyl-9-BBN gave a ρ of +0.49.The relative rates are consistent with a hydride addition to the carbonyl carbon in the rate-determining step.Activation parameters were obtained for the reaction of three benzaldehydes with B-n-octyl-9-BBN.The major barrier to the reaction is entropy.The large negative entropies of activation (-43 to -49 eu) indicate a highly ordered transition state.It is postulated that an organoborane-carbonyl oxygen complex is an intermediate in the reduction.
Effect of Water on the Extraction and Reactions of Fluoride Anion by Quaternary Ammonium Phase-Transfer Catalysts
Dermeik, Salman,Sasson, Yoel
, p. 879 - 882 (1985)
The maximum conversion of the fluoride-chloride exchange reaction RCl + KF -> RF + KCl catalyzed by quaternary onium salts was found to be strongly dependent on the water content of the inorganic salt.A maximum conversion was obtained when the potassium fluoride contained 0.33 mol of water per mol of KF.This phenomenon is due to better extraction of the fluoride anion when the KF is drier, offset by decomposition of the catalyst in the absence of water.It was shown that the selectivity constant KselCl/F is dependent on composition of the inorganic salt and on temperature.Rate measurements indicate that the mechanism proposed by Starks for liquid-liquid exchange reactions is valid also in a solid-liquid process which is also chemically controlled.
On the activation of Mo2B and MoB catalysts in oct-1-ene epoxidation with tert-butyl hydroperoxide
Nykypanchuk,Komarenskaya,Chernii
, p. 212 - 216 (2014)
The activation of Mo2B and MoB catalyst in the epoxidation of oct-1-ene with tert-butyl hydroperoxide is reported. The activation process is described by the Avraami-Erofeev topokinetic equation and includes two successive steps, viz.; the nucleation and formation of a new active phase. The epoxide is produced only when the activated form of the catalyst is involved. The effective and topochemical constants of the process have been determined.
Deamination of n-octylamine in aqueous solution: The substitution/elimination ratio is not altered by a change of 108 in hydroxide ion concentration
Monera,Chang,Means
, p. 5424 - 5426 (1989)
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An unprecedented α-olefin distribution arising from a homogeneous ethylene oligomerization catalyst
Tomov, Atanas K.,Chirinos, Juan J.,Long, Richard J.,Gibson, Vernon C.,Elsegood, Mark R. J.
, p. 7704 - 7705 (2006)
Treatment of the bis(benzimidazolyl)amine chromium complex 2 with ethylene in the presence of MAO affords an exceptionally active oligomerization catalyst and an unprecedented distribution of 1-olefin products in which the C4n series is much more abundant than the C4n+2 series. Deuterium labeling studies are consistent with a metallacyclic chain growth mechanism in which the unusual product distribution arises from the interplay of two sites. Copyright
Convenient and general synthesis of 1-monoorganyl- And 1,2-diorganylcyclobutenes via cyclialkylation
Negishi, Ei-Ichi,Liu, Fang,Choueiry, Daniele,Mohamud, Mohamud M.,Silveira Jr., Augustine,Reeves, Mark
, p. 8325 - 8328 (1996)
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Catalytic Conversion of Alcohols Part 16. - Attempt to Correlate the ESCA Oxygen 1s Binding Energy with the Selectivity
Davis, Burtron H.,Russell, Sayra N.,Reucroft, Philip J.,Shalvoy, Richard B.
, p. 1917 - 1922 (1980)
Neither the dehydration nor the terminal alkene selectivity for the conversion of secondary and tertiary alcohols over more than twenty metal oxide catalysts was related to the oxigen 1s binding energy of the catalyst.Even the attempt to correlate the selectivity to the oxigen 1s binding energy within a smaller group of metal oxide catalysts, Group IIIA or IVB, was not successful.
Chemically induced dynamic nuclear polarization and the mechanism of the reaction of Et3Al with CCl4 in the presence of transition metal complexes
Sadykov,Safina,Teregulov,Paramonov
, p. 497 - 501 (2010)
Integral effects of chemically induced 1H and 13C nuclear polarization are reported for the reaction of Et3Al with CCl4 catalyzed by Pd(acac)2, Cu(acac)2, and Cp2TiCl2; for the reaction of (n-C8H 17)3Al with CCl4 in the absence of a catalyst and in the presence of Ni(acac)2; and for the reaction of the cyclic organoaluminum compound 1-ethyl-3-butylaluminacyclopentane with CCl4 in the presence of Pd(acac)2. A scheme of the catalytic cycle of this reaction predicting the formation of both radical and nonradical products is derived from the observed chemically induced dynamic nuclear polarization (CIDNP) effects and from data on the products of the reaction between Et 3Al and CCl4 in the presence of Pd(acac)2. According to the results of qualitative analysis of the CIDNP effects, the reactions of the trialkylalanes and the cyclic organoaluminum compound with CCl4 in the presence of various metal complexes proceeded via similar mechanisms.
Whishman
, p. 1284 (1961)
A Heterogeneous Metal-Free Catalyst for Hydrogenation: Lewis Acid–Base Pairs Integrated into a Carbon Lattice
Ding, Yuxiao,Huang, Xing,Yi, Xianfeng,Qiao, Yunxiang,Sun, Xiaoyan,Zheng, Anmin,Su, Dang Sheng
, p. 13800 - 13804 (2018)
Designing heterogeneous metal-free catalysts for hydrogenation is a long-standing challenge in catalysis. Nanodiamond-based carbon materials were prepared that are surface-doped with electron-rich nitrogen and electron-deficient boron. The two heteroatoms are directly bonded to each other to form unquenched Lewis pairs with infinite π-electron donation from the surrounding graphitic structure. Remarkably, these Lewis pairs can split H2 to form H+/H? pairs, which subsequently serve as the active species for hydrogenation of different substrates. This unprecedented finding sheds light on the uptake of H2 across carbon-based materials and suggests that dual Lewis acidity–basicity on the carbon surface may be used to heterogeneously activate a variety of small molecules.
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Herbrandson et al.
, p. 3301 (1958)
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Diverse Reactivity of a Rhenium(V) Oxo Imido Complex: [2 + 2] Cycloadditions, Chalcogen Metathesis, Oxygen Atom Transfer, and Protic and Hydridic 1,2-Additions
Arnold, John,Bergman, Robert G.,Cortes, Emmanuel A.,Fostvedt, Jade I.,Jain, Anukta,Lohrey, Trevor D.,Oanta, Alexander K.
, (2020)
We present a wide range of reactivity studies focused on the rhenium(V) oxo imido complex (DippN)(O)Re(BDI) (1, Dipp = 2,6-diisopropylphenyl and BDI = N,N′-bis(2,6-diisopropylphenyl)-3,5-dimethyl-β-diketiminate). This complex, which was previously shown to possess a highly polarized Re oxo moiety, has proven to be a potent nucleophile and a valuable precursor to a variety of rare structural motifs in rhenium coordination complexes. For example, the Re oxo moiety of 1 undergoes [2 + 2] cycloadditions with carbodiimides, isocyanates, carbon dioxide, and isothiocyanates at room temperature. In the case of CO2, the cycloadduct with 1 (a carbonate complex) undergoes the facile ejection of CO2, demonstrating that this binding process is reversible. In the case of isothiocyanate, chalcogen metathesis with 1 takes place readily as the inclusion of a second equivalent of substrate in the reaction mixture rapidly yields a dithiocarbamate complex. This metathesis process was extended to the reactivity of 1 with phosphine chalcogenides, leading to the isolation of terminal sulfido imido and selenido imido complexes. Attempts to complete this series and generate the analogous terminal telluride led to the formation of a bidentate tritelluride (Te32-) complex. Triethylphosphine could only undergo oxygen atom transfer (OAT) with 1 under pressing thermal conditions that also led to C-N cleavage of the BDI ligand. In contrast, OAT between 1 and CO or 2,6-xylylisocyanide (XylNC) was found to be much more facile, proceeding within seconds at room temperature. While the addition of excess CO led to a rhenium(III) imido dicarbonyl complex, we found that the addition of 2 equiv of XylNC was necessary to promote OAT, resulting in the isolation of a rare example of a stable metal isocyanate complex. Our experimental observations of CO and XylNC and their OAT reactions with 1 inspired a mechanistic computational study to probe the intermediates and kinetic barriers along these reaction pathways. Finally, we describe 1,2-additions of both protic and hydridic substrates with the Re oxo moiety of 1, which most notably led to the syntheses of an uncommon example of a terminal rhenium hydroxide complex and an oxo-bridged Re-O-Zr hetero-bi-metallic complex that was generated using Schwartz's reagent (Cp2ZrHCl). A brief discussion of a potential alternative route to 1 is also presented.
N,N-Diphospholylamines-A new family of ligands for highly active, chromium-based, selective ethene oligomerisation catalysts
Stennett, Tom E.,Hey, Thomas W.,Ball, Liam T.,Flynn, Stephanie R.,Radcliffe, James E.,Mcmullin, Claire L.,Wingad, Richard L.,Wass, Duncan F.
, p. 2946 - 2954 (2013)
A series of new diphosphazane (PNP) ligands that contain 2,3,4,5-tetraethylphosphole or dibenzophosphole moieties has been synthesised. The new compounds have been screened for chromium-catalysed, selective ethene oligomerisation by insitu combination with CrCl3(thf)3 and methylaluminoxane (MAO). The ligands derived from 2,3,4,5-tetraethylphosphole produce highly active catalysts for ethene oligomerisation, which show excellent selectivity to C6 and C8 linear α-olefins. Complexes of the form [Cr(CO)4L] were synthesised and studied by IR spectroscopy and single-crystal XRD. Variable-temperature NMR spectroscopy was used to investigate restricted P=N rotation in compounds with bulky nitrogen substituents. Top hole phosphole! New diphosphazane ligands based on phosphole donors produce highly active catalysts with chromium for the selective oligomerization of ethene. Modification of the backbone nitrogen substituent gives excellent control over the C6/C8 selectivity. MAO=methylaluminoxane.
The Combination of Potassium Fluoride and Calcium Fluoride: A Useful Heterogeneous Fluorinating Reagent
Ichihara, Junko,Matsuo, Toshiya,Hanafusa, Terukiyo,Ando, Takashi
, p. 793 - 794 (1986)
The combination of potassium fluoride and calcium fluoride was found to be an effective and practical solid reagent for the fluorination of various organic chlorides and bromides under mild conditions.
Unexpectedly selective hydrogenation of phenylacetylene to styrene on titania supported platinum photocatalyst under 385 nm monochromatic light irradiation
Lian, Juhong,Chai, Yuchao,Qi, Yu,Guo, Xiangyang,Guan, Naijia,Li, Landong,Zhang, Fuxiang
, p. 598 - 603 (2020)
Conversion of alkynes to alkenes by photocatalysis has inspired extensive interest, but it is still challenging to obtain both high conversion and selectivity. Here we first demonstrate the photocatalytic conversion of phenylacetylene (PLE) to styrene (STE) with both high conversion and selectivity by using the titania (TiO2) supported platinum (Pt) as photocatalyst under 385 nm monochromatic light irradiation. It is demonstrated that the conversion rate of PLE is strongly dependent on the content of Pt cocatalyst loaded on the surface of TiO2. Based on our optimization, the conversion of PLE and the selectivity towards STE on the 1 wt% Pt/TiO2 photocatalyst can unexpectedly reach as high as 92.4% and 91.3%, respectively. The highly selective photocatalytic hydrogenation can well be extended to the conversion of other typical alkynes to alkenes, demonstrating the generality of selective hydrogenation of C≡C over the Pt/TiO2 photocatalyst.
Selective ethylene oligomerization in the presence of ZnR2: Synthesis of terminally-functionalized ethylene oligomers
Son, Kyung-Sun,Waymouth, Robert M.
, p. 3515 - 3520 (2010)
The selective oligomerization of ethylene to 1-hexene or 1-octene provides a selective route to these valuable α-olefins. Selective trimerization and tetramerization of ethylene with Cr catalysts have been proposed to occur by a mechanism involving metallacycle intermediates. We envisioned that the intermediacy of metallacycles could provide an opportunity to generate new classes of functionalized ethylene oligomers by chain transfer to a transmetalation reagent. Herein, we report the influence of transmetalation agents such as zinc alkyls on the selectivity of ethylene oligomerization with a Cr(PNP)Cl3/MAO system (PNP = Ph2PN(iPr) PPh2). Oligomerization of ethylene with Cr(PNP)Cl3/MAO at 200 psig of ethylene at 25 or 45 °C generates 1-hexene, 1-octene, C 10-C22 oligomers, and polyethylene. The addition of ZnR2 increases the productivity and selectivity for C 10-C22 oligomers and results in a decrease in the amount and molecular weight of the polyethylene generated. Analysis of the product distribution after quenching with D2O reveals that 1-hexene and 1-octene are unlabeled, but that all higher oligomers are deuteriated alkanes or alkenes, depending on the nature of the zinc alkyl (R = Me, Et, Bu). Mechanistic proposals are presented to explain the formation of differentially functionalized coproducts in the presence of zinc alkyls. These studies reveal that oligomerization in the presence of ZnR2 provides a new route to end-functionalized ethylene oligomers and new insights on the reactivity of metallacycle intermediates in the Cr-catalyzed oligomerization of ethylene.
LIGANDS FOR PRODUCTION OF 1-HEXENE IN CHROMIUM ASSISTED ETHYLENE OLIGOMERIZATION PROCESS
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Paragraph 0054-0056, (2022/01/12)
Catalyst compositions and processes for the oligomerization of ethylene to 1-hexene are described. The catalyst composition includes a triamino bisphospino (NPNPN) ligand system with specific phosphorous and nitrogen ligands. The terminal nitrogen atoms include linear alkyl hydrocarbons that differ in the number of carbon atoms by 3.
Diverse Mechanistic Pathways in Single-Site Heterogeneous Catalysis: Alcohol Conversions Mediated by a High-Valent Carbon-Supported Molybdenum-Dioxo Catalyst
Bedzyk, Michael J.,Das, Anusheela,Kratish, Yosi,Li, Jiaqi,Ma, Qing,Marks, Tobin J.
, p. 1247 - 1257 (2022/02/07)
With the increase in the importance of renewable resources, chemical research is shifting focus toward substituting petrochemicals with biomass-derived analogues and platform-molecule transformations such as alcohol processing. To these ends, in-depth mechanistic understanding is key to the rational design of catalytic systems with enhanced activity and selectivity. Here we discuss in detail the structure and reactivity of a single-site active carbon-supported molybdenum-dioxo catalyst (AC/MoO2) and the mechanism(s) by which it mediates alcohol dehydration. A range of tertiary, secondary, and primary alcohols as well as selected bio-based terpineols are investigated as substrates under mild reaction conditions. A combined experimental substituent effect/kinetic/kinetic isotope effect/EXAFS/DFT computational analysis indicates that (1) water assistance is a key element in the transition state; (2) the experimental kinetic isotopic effect and activation enthalpy are 2.5 and 24.4 kcal/mol, respectively, in good agreement with the DFT results; and (3) several computationally identified intermediates including Mo-oxo-hydroxy-alkoxide and cage-structured long-range water-coordinated Mo-dioxo species are supported by EXAFS. This structurally and mechanistically well-characterized single-site system not only effects efficient transformations but also provides insight into rational catalyst design for future biomass processes.
Phosphorus and nitrogen-doped palladium nanomaterials support on coral-like carbon materials as the catalyst for semi-hydrogenation of phenylacetylene and mechanism study
Ma, Lei,Jiang, Pengbo,Wang, Kaizhi,Lan, Kai,Huang, Xiaokang,Yang, Ming,Gong, Li,Jia, Qi,Mu, Xiao,Xiong, Yucong,Li, Rong
, (2021/02/26)
In this work, two types of polyporous and coral-like materials (CN) with high specific surface area are prepared using sodium glutamate as a carrier. At the same time, a CN-supported phosphorus-nitrogen-doped palladium nanomaterial CN-P-Pd is synthesized and applied to the preparation of styrene by selective hydrogenation of phenylacetylene under mild conditions. As shown in the TEM images, Pd nanoparticles with a particle size of about 4.4 nm are uniformly dispersed on the surface of the carrier. The results of N2 adsorption–desorption reveal that the surface area of the prepared catalyst (CN-P-Pd) is 1307 m2g?1. In addition, the experimental exploration shows the intervention of P in carbon-nitrogen materials can contribute to improve the selectivity of the reaction, which can be attributed to the fact that P element can change the electron density of Pd. Meanwhile, it is found that the solvent not only affects the activity of catalyst, but also the selectivity of the reaction. Kinetic study shows the activation energy of the reaction is 4.5 kJ/mol. With the increase of the reaction temperature, the dissolution rate of hydrogen in the solvent gradually slows down, which inhibits the progress of the reduction reaction. Mechanistic studies demonstrate that the carbon-nitrogen materials have strong adsorption capacity for substrates, and also provide more adsorption sites for phenylacetylene. Additionally, the optimal catalyst (CN-P-Pd) also has high reaction activity to other alkynes and the conversion can reach at 95%. Moreover, the optimal catalyst can be reused several times without significant reduction in reaction activity.