106-98-9Relevant articles and documents
Isolation and Direct Observation of Intramolecular Hydroacylation of a cis-Hydridopent-4-enoylrhodium(III) Complex
Milstein, David
, p. 1357 - 1358 (1982)
A stable cis-hydridopentenoylrhodium(III) trimethylphosphine complex, isolated from oxidative addition of pent-4-enal to RhCl(PMe3)3, undergoes intramolecular hydroacylation to cyclopentanone.
Synthesis of butene - ethylene and hexene - butene - ethylene copolymers from ethylene via tandem action of well-defined homogeneous catalysts [15]
Komon, Zachary J.A.,Bu, Xianhui,Bazan, Guillermo C.
, p. 1830 - 1831 (2000)
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Selective dimerization of ethylene to but-1-ene under the conditions of industrial process. I. Influence of temperature and pressure on the rate of the process in a bubbling type reactor
Zhukov,Val'kovich,Skorik,Petrov,Belov
, p. 1195 - 1200 (2007)
Analysis of mass and heat balance in the reaction node of the process of ethylene dimerization into but-1-ene under the industrial conditions is performed. It is found that ethylene concentration in the reactor liquid phase by a complex way depends on the reactor temperature, pressure and but-1-ene concentration in the liquid phase. Optimal process temperature is 80-90°C, operating pressure in the reactor is 0.6-0.8 MPa. Increase in pressure above 1 MPa practically excludes heat withdraw via but-1-ene evaporation and makes the system of heat withdrawing ineffective.
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Dunning
, p. 551 (1953)
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Leaving group effects in gas-phase substitutions and eliminations
Gronert, Scott,Fagin, Adelaide E.,Okamoto, Keiko,Mogali, Sudha,Pratt, Lawrence M.
, p. 12977 - 12983 (2004)
Using a methodology recently developed for studying the product distributions of gas-phase SN2 and E2 reactions, the effect of the leaving group on the reaction rate and branching ratio was investigated. Using a dianion as the nucleophile, reactions with a series of alkyl bromides, iodides, and trifluoroacetates were examined. The alkyl groups in the study are ethyl, n-propyl, n-butyl, isobutyl, isopropyl, sec-butyl, and tert-butyl. The data indicate that leaving group abilities are directly related to the exothermicities of the reaction processes in both the gas phase and the condensed phase. Gas-phase data give a reactivity order of iodide > trifluoroacetate > bromide for SN2 and E2 reactions. Previous condensed phase data indicate a reactivity order of iodide > bromide > trifluoroacetate for substitution reactions; however, the basicities of bromide and trifluoroacetate are reversed in the condensed phase so this reactivity pattern does reflect the relative reaction exothermicities. Aside from this variation, the gas-phase data parallel condensed phase data indicating that the substituent effects are rooted in the nature of the alkyl substrate rather than in differences in solvation. The experimental data are supported by calculations at the MP2/6-311+G(d,p)//MP2/6-31+(d) level.
Selective Catalytic Dimerisation of Ethylene to But-1-ene by 2-CHPMe2)>
Gibson, Vernon C.,Kee, Terence P.,Poole, Andrew D.
, p. 1720 - 1722 (1990)
2-CHPMe2)> reacts with an excess of ethylene at 70 deg C to give but-1-ene cleanly and selectively.
New air stable cationic methallyl Ni complexes bearing imidoyl-indazole carboxylate ligand: Synthesis, characterization and their reactivity towards ethylene
Cabrera, Alan R.,Martinez, Ivan,Daniliuc, Constantin G.,Galland, Griselda B.,Salas, Cristian O.,Rojas, Rene S.
, p. 19 - 26 (2016)
Three new neutral N,N imidoyl-indazole ligands with a methoxycarbonyl functional group (1-3) and three new air-stable cationic methallyl nickel complexes (4-6) were prepared. These compounds were characterized by NMR, FT-IR and elemental analyses. In addition, compounds 1, 2, 3 and 4 were analyzed using X-ray diffraction. An evaluation of the reactivity of complexes 4-6 toward ethylene was conducted by using 5 equivalents of B(C6F5)3. At 1 bar of ethylene and 20 °C, only complexes 4 and 6 were able to produce butene, showing unusual air stability and dimerizing ethylene even after exposure to air for 48 h. By increasing the pressure to 12 bar at 20 °C, complex 6 showed a catalytic activity of 401 Kg product (mol Ni)-1 h-1, producing a low molecular weight polyethylene (26.6 Kg/mol) with almost exclusively methyl branches (2.3 mol%). By increasing the temperature to 60 °C at 12 bar of ethylene, the system 6/B(C6F5)3 increased its catalytic activity to 487 Kg product (mol Ni-1) h-1, but produced a significant decrease in the molecular weight of the polymer (1.8 Kg/mol) and a broad distribution of branches.
Oxidative Addition of Vinyl Acetate to Ruthenium (0) Involving Carbon Oxygen Bond Cleavage Forming a Novel Vinyl(aceto)tris(triethylphosphine)ruthenium(II)
Komiya, Sanshiro,Suzuki, Jun-ichi,Miki, Kunio,Kasai, Nobutami
, p. 1287 - 1290 (1987)
Vinyl acetate oxidatively adds to (1,5-cyclooctadiene)(1,3,5-cyclooctatriene)ruthenium(0) in the presence of triethylphosphine to give mer-vinyl(acetato)tris(triethylphosphine)ruthenium(II) at 50 deg C in hexane, which has been unequivocally characterized by 1H, (31)P, and (13)C NMR, IR, elemental analysis, and X-ray structure analysis.
Ethylene Oligomerization to Select Oligomers on Ni-ETS-10
Thakkar, Jay,Yin, Xinyang,Zhang, Xueyi
, p. 4234 - 4237 (2018)
The oligomerization of short alkenes (ethylene and propylene) can be used for producing commodity chemicals. Various catalysts have been used for alkene oligomerization, among which ordered microporous catalysts are thermally and mechanically stable and are already established for large-scale industrial applications. In this work, we demonstrate ethylene oligomerization reaction on a microporous titanosilicate ETS-10 (Engelhard Titanosiliate-10) exchanged with Ni2+ (Ni-ETS-10). We demonstrate a template-free and fluoride-free ETS-10 synthesis method that does not produce impurities commonly seen in hydrothermal ETS-10 synthesis. Ni-ETS-10 showed high C2 conversion rate, high selectivity to C4 and high stability comparing to other microporous catalysts investigated in this work for ethylene oligomerization reaction.
Dehydrogenation properties of ZnO and the impact of gold nanoparticles on the process
Suchorska-Wo?niak, Patrycja,Rac, Olga,Klimkiewicz, Roman,Fiedot, Marta,Teterycz, Helena
, p. 135 - 145 (2016)
The article presents the results of catalytic and surface properties of pure zinc oxide synthesized by hydrothermal method and surface-doped with gold nanoparticles. As a test reaction, the catalytic transformation of n-butyl alcohol towards the dehydrogenation or bimolecular condensation of symmetric ketone or an ester was studied. The tested materials catalyse both consecutive reactions, wherein the transformation towards the ketone is dependent on the presence of surface oxygen vacancies, whose concentration depends on the temperature. In turn, the transformation to the ester occurs in the presence of gold nanoparticles deposited on the surface of zinc oxide. The difference in work function of electrons from these materials create a change in the electron concentration in the surface area and will shift the balance of the coupling reaction of hydrogen with lattice oxygen, which prefers the formation of aldehyde and ester. The results were compared with the catalytic properties of other previously studied oxide systems in this group of changes. This analysis enabled the development of the mechanism of transformation and explanation of the impact of gold on the kinetics of the process.
Mechanistic Study of Carbon Monoxide Hydrogenation over Ruthenium Catalysts
Kobori, Yoshihiro,Yamasaki, Hirofumi,Naito, Shuichi,Onishi, Takaharu,Tamaru, Kenzi
, p. 1473 - 1490 (1982)
The mechanism of the hydrogenation of carbon monoxide to hydrocarbon products over ruthenium catalysts has been investigated.By measuring the adsorption and observing the infrared adsorption spectra of the adsorbed species during the course of the reaction, the accumulation of surface hydrocarbon species on the ruthenium catalysts was confirmed, whereas most of the surface was covered by molecularly adsorbed carbon monoxide.The reaction intermediate was examined using carbon-13.The reactivity of deposited carbon formed by the Boudouard reaction has also been studied using carbon-13.It is concluded from the behaviour of the surface species under the reaction conditions that all the hydrocarbon products are produced via dissociatively adsorbed CO with no CO insertion.The rate-determining step has been examined, leading to the conclusion that it comprises the conversion of C1 intermediates to the reaction products.
Sterically modulated binuclear bis-α-diimine Pd(II) complexes: Synthesis, characterization, DFT studies and catalytic behavior towards ethylene oligomerization
Netalkar, Sandeep P.,Budagumpi, Srinivasa,Abdallah, Hassan H.,Netalkar, Priya P.,Revankar, Vidyanand K.
, p. 559 - 565 (2015)
A series of Pd(II) complexes of bis-α-diimine derivatives with substituent at 2,6-positions of aniline increasing sterically from Me Et iPr groups have been synthesized to act as a versatile set of catalytic precursors for oligomerization of ethylene
Structrure and Reactivity of Lithium Amides. Role of Aggregates, Mixed Aggregates, Monomers, and Free Ions on the Rates and Selectivities of N-Alkylation and E2 Elimination
DePue, Jeffrey S.,Collum, David B.
, p. 5524 - 5533 (1988)
Rate studies of the N-alkylation of lithium diphenylamide with n-butyl bromide in THF/hydrocarbon mixtures (THF=tetrahydrofuran) are described.Dramatic induction periods observed for the N-alkylation at low THF concentrations are described to the intervention of reactive mixed dimers of lithium diphenylamide and lithium bromide.In the presence of 1.0 equiv. of added lithium bromide, the alkylation rate exhibits a first-order dependence on both the mixed aggregate and n-butyl bromide concentration, indicating the contribution of an additional, highly solvent dependentalkylation pathway.This latter pathway exhibits fractional-order dependence on the amide concentration, approximate first order dependence on the n-butyl bromide concentration, and a seventh-order dependence on the THF concentration.Common ion rate inhibitions by lithium perchlorate and lithium tetraphenylborate, a significant dependence on dielectric effects, and the observed reaction orders implicate a mechanism involving predissociation of free lithium ions.The appearence of competitive eliminations of n-alkyl bromides to form 1-alkenes coincides with the appearence of the free ion alkylation pathway.
CATALYTIC DEHYDRATION OF ALCOHOLS STUDIED BY REVERSED-FLOW GAS CHROMATOGRAPHY.
Karaiskakis, George,Katsanos, Nicholas A.,Georgiadou, Irene,Lycourghiotis, Alexis
, p. 2017 - 2022 (1982)
With the aid the new technique of reversed-flow gas chromatography (r.f.g.c.), rate constants and activation parameters for the dehydration of propan-1-ol, propan-2-ol and butan-1-ol over 13X molecular sieve and γ-aluminium oxide were determined.These parameters were found to be in agreement with those determined by other techniques.Also, in one case the fraction of the surface which is catalytically active was estimated, and was found to coincide with the fractional conversion of reactant into products.
Synthesis and reactivity in ethylene oligomerization by heteroscorpionate dibromonickel(II) complexes
Zubkevich, Sergei V.,Gagieva, Svetlana Ch.,Tuskaev, Vladislav A.,Dorovatovskii, Pavel V.,Khrustalev, Victor N.,Sizov, Alexandr I.,Bulychev, Boris M.
, p. 58 - 67 (2017)
Novel heteroscorpionate ligands were synthesized by a Peterson rearrangement during the reaction of 2-pyridinecarboxaldehyde (or 2-quinolinecarboxaldehyde) and 1,1-carbonyl-bis(pyrazoles). Nickel(II) dibromide reacts with these ligands in THF to give the heteroscorpionate dibromo complexes of general formula LNiBr2. Crystal structures of two full-sandwich heteroscorpionate Ni(II) complexes were determined. Preliminary studies of catalytic activity in ethylene oligomerization using different organoaluminum cocatalysts were performed. The addition of one equivalent of triphenylphosphine resulted in increased catalytic activity for most examples. The catalyst system of (2-[bis(3,5-dimethylpyrazol-1-yl)methyl]pyridine nickel(II) dibromide/Et2AlCl/PPh3dimerized ethylene with an activity of 650?g oligomer mol?1?Ni?h?1while the share of 1-butene in the mixture has reached 75%. Tris(3,5-dimethylpyrazol-1-yl)methyl nickel(II) dibromide, activated by Et2AlCl/PPh3produced isobutylene (75% of the butene fraction).
ACTIVATION OF THE Ti(OC4H9)4-Al(C2H5)C CATALYTIC SYSTEM IN THE SELECTIVE DIMERIZATION OF ETHYLENE TO 1-BUTENE BY THE GRIGNARD REAGENT
Dzhabieva, Z. M.,Babkina, O. N.,Belov, G. P.,Zhukov, V. I.,D'yachkovskii, F. S.
, p. 1781 - 1786 (1992)
The effect of an organomagnesium compound on the dimerization of ethylene to 1-butene was studied. The organomagnesium compound increases the catalytic activity of the Ti(OC4H9)4-Al(C2H5)3 system by 5-10 times. A high degree of selectivity (up to 99percent) with respect to 1-butene was obtained. This makes it possible to eliminate a series of technological difficulties involved in the industrial production of 1-butene. The kinetics of the reduction of Ti(OC4H9)4 by butylmagnesium chloride were studied by ESR and polarography. Keywords: dimerization, kinetics, ethylene, organomagnesium compound, 1-butene, selectivity, catalytic activity, polarography, reduction.
Evidence for the activation of unstrained carbon-carbon bonds by bare transition-metal ions M+ (M = Fe, Co) without prior C-H bond activation
Karrass, Sigurd,Schwarz, Helmut
, p. 2034 - 2040 (1990)
The metastable ion (MI) decompositions of RNH2/M+ complexes (R = (C2H5)2CHCH2, C2H5C(CH3)2CH2; M - Fe, Co) in the gas phase have been studied by tandem mass spectrometry with a four-sector instrument of BEBE configuration. The analyses of the MI spectra of isotopically labeled complexes uncover processes which inter alia demonstrate that the loss of C4H8 corresponds to a reaction in which site-specific oxidative addition of an unstrained C-C bond to the anchored transition-metal ion M+ takes place without prior C-H bond activation. The intramolecular methyl migration preceding the elimination of C4H8 is subject to a secondary kinetic isotope effect of kH/kD = 1.33 for M+ = Fe+ and kH/kD = 1.15 for M+ = Co+ per D atom. Additional processes observed correspond to the generation of molecular hydrogen, methane, ethylene and ethane. All reactions are highly specific, and mechanisms are suggested that are in keeping with the labeling data. For example, both H2 and C2H4 are formed via remote functionalization involving the ω/ (ω - 1) positions of the ethyl side chain of the amines. Ethane contains an intact ethyl group, and one hydrogen is provided via specific β-hydrogen transfer which does not involve the chemically activated CH2NH2 group. This methylene group is also inert with regard to the reductive elimination of methane from CH3CH2C(CH3)2CHNH 2/Co+. According to the labeling experiments, the intermediate from which CH4 is lberated contains an intact CH3 group that originates from the quaternary carbon center; the missing hydrogen atom is provided to roughly the same amount by both the second CH3 group of C(2) and the CH2 unit of the ethyl group. Again, the -CH2NH2 part does not serve as a hydrogen source for CH4.
Direct transformation of ethylene into propylene catalyzed by a tungsten hydride supported on alumina: Trifunctional single-site catalysis
Taoufik, Mostafa,Le Roux, Erwan,Thivolle-Cazat, Jean,Basset, Jean-Marie
, p. 7202 - 7205 (2007)
A trifunctional single-site catalyst: Ethylene is selectively transformed into propylene in a continuous-flow reactor in the presence of the supported tungsten hydride W(H)3/Al2O3. Since the catalyst is also active for olefin metathesis, the reaction is likely to proceed at a "trifunctional catalytic site" by ethylene dimerization, butene isomerization, and cross-metathesis of ethylene with 2-butenes (see picture). (Chemical Equation Presented).
Chain-selective and regioselective ethylene and styrene dimerization reactions catalyzed by a well-defined cationic ruthenium hydride complex: New insights on the styrene dimerization mechanism
Lee, Do W.,Yi, Chae S.
, p. 3413 - 3417 (2010)
The cationic ruthenium hydride complex [(η6-C 6H6)(PCy3)(CO)RuH]+BF 4- was found to be a highly regioselective catalyst for the ethylene dimerization reaction to give 2-butene products (TOF = 1910 h -1, >95% selectivity for 2-butenes). The dimerization of styrene exclusively produced the head-to-tail dimer (E)-PhCH(CH3)CH=CHPh at an initial turnover rate of 2300 h-1. A rapid and extensive H/D exchange between the vinyl hydrogens of styrene-d8 and 4-methoxystyrene was observed within 10 min without forming the dimer products at room temperature. The inverse deuterium isotope effect of k H/kD = 0.77 ± 0.10 was measured from the first-order plots on the dimerization reaction of styrene and styrene-d 8 in chlorobenzene at 70 °C. The pronounced carbon isotope effect on both vinyl carbons of styrene as measured by using Singletons method ( 13C(recovered)/13C(virgin) at C1 = 1.096 and C2 = 1.042) indicates that the C-C bond formation is the rate-limiting step for the dimerization reaction. The Eyring plot of the dimerization of styrene in the temperature range of 50-90 °C led to ΔH? = 3.3(6) kcal/mol and ΔS? = -35.5(7) eu. An electrophilic addition mechanism has been proposed for the dimerization of styrene.
Synthesis of a ni complex chelated by a [2.2]paracyclophane-functionalized diimine ligand and its catalytic activity for olefin oligomerization
Osakada, Kohtaro,Takeuchi, Daisuke,Tojo, Yoshi-Aki
, (2021)
A diimine ligand having two [2.2]paracyclophanyl substituents at the N atoms (L1) was prepared from the reaction of amino[2.2]paracyclophane with acenaphtenequinone. The ligand re-acts with NiBr2(dme) (dme: 1,2-dimethoxyethane) to form the dibromonickel complex with (R,R) and (S,S) configuration, NiBr2(L1). The structure of the complex was confirmed by X-ray crystallog-raphy. NiBr2(L1) catalyzes oligomerization of ethylene in the presence of methylaluminoxane (MAO) co-catalyst at 10–50 °C to form a mixture of 1-and 2-butenes after 3 h. The reactions for 6 h and 8 h at 25 °C causes further increase of 2-butene formed via isomerization of 1-butene and formation of hexenes. Reaction of 1-hexene catalyzed by NiBr2(L1)–MAO produces 2-hexene via isom-erization and C12 and C18 hydrocarbons via oligomerization. Consumption of 1-hexene of the reaction obeys first-order kinetics. The kinetic parameters were obtained to be ΔG≠ = 93.6 kJ mol?1, ΔH≠ = 63.0 kJ mol?1, and ΔS≠ = ?112 J mol?1deg?1. NiBr2(L1) catalyzes co-dimerization of ethylene and 1-hexene to form C8 hydrocarbons with higher rate and selectivity than the tetramerization of eth-ylene.
CATALYTIC ISOMERIZATION OF BUTENES OVER A SULFURIC ACID-GRAPHITE INTERCALATION COMPOUND.
Tsuchiya,Hara,Imumura
, p. 1539 - 1540 (1983)
The relative rate constants and the activation energies of the isomerization of butenes over a sulfuric acid-graphite intercalation compound have been measured cis-2-Butene is more reactive than 1-butene. the reaction profile shown on the triangular graph is of the trans-convex type.
Di-μ-carbonyl-tris(cyclopentadienylnickel) as a Cluster Precursor to a Highly Active Ethylene Oligomerization Catalyst
Beach, David L.,Kobylinski, Thaddeus P.
, p. 933 - 934 (1980)
The first example of the use of a cyclopentadienylnickel cluster to effect catalytic oligomerization of an olefin is reported; when a benzene solution of di-μ-carbonyl-tris(cyclopentadienylnickel) is allowed to react with silica-alumina and subsequently heated to 150 degC, a highly active catalyst is formed which oligomerizes ethylene to higher olefins with turnover frequencies greater than 105 mol ethylene per mol (η5-C5H5)3Ni3(CO)2 per h.
The Dehydrochlorination of gem-Dichloroalkane and the Formation of Dienes from the Reactions of Butenes and Cyclohexene with Chlorine through Molten Salt
Kikkawa, Shoichi,Nomura, Masakatsu,Shimizu, Michimasa
, p. 2586 - 2591 (1980)
The dehydrochlorination of 1,1-dichloropropane and 1,1-dichloro-3-methylbutane was carried out over molten salt catalysts (mainly ZnCl2-containing melts) using a conventional flow system.The cis/trans ratio (1.8) of the resulting olefins from 1,1-dichlorobutane was found to stand between the ratio (1.4) with 1,1-dichloro-3-methylbutane and the ratio (2.2) with 1,1-dichloropropane; this can be explained by considering the stereochemistry of the adsorbed carbonium ions.The detailed results of the reactions of three butene isomers with chlorine through molten salts were presented.The selective formation of butadiene was explained in terms of the thermally assisted attack of chlorine in the allylic positions of butene, followed by the 1,2- or 1,4-elimination of HCl from chlorobutenes, a process which is strongly assisted by the ZnCl2-containing melts.The reaction of 2-methyl-2-butene and cyclohexene with chlorine through molten salts was also undertaken.The addition of Zn powder to ZnCl2 melts in advance was found to improve the selectivity for the formation of isoprene and cyclohexadiene.Because the HCl evolved reacts instantly with Zn powder to afford ZnCl2 and hydrogen, Zn powder substantially prohibits the addition of HCl to dienes yielding chlorobutenes and chlorocyclohexenes.
SHS Membrane for the Dehydrogenation of n-Butanol to Butadienes
Uvarov,Alymov,Loryan,Shustov,Fedotov,Tsodikov
, p. 798 - 802 (2019)
Abstract—: We have synthesized catalytically active membranes based on α- and γ-Al2O3 powders for the dehydration and dehydrogenation of butyl alcohol to butadiene and hydrogen. The open porosity of the samples obtained in this study is 41% in the case of α-Al2O3 and 38% in the case of γ-Al2O3. The open pore size is 4.6–5.1 μm in the α-Al2O3 material and 0.5–0.8 μm in the γ-Al2O3 material. We have implemented a hybrid, membrane–catalytic process for the dehydrogenation of butanol by combining reaction and hydrogen separation steps in a single device. It has been demonstrated that the dehydration of n-butanol on a γ-Al2O3 converter leads to the formation of a butylene fraction with a selectivity of 99.88–100% at a temperature of 300°C, which is 50°C lower than in the case of commercially available gamma-alumina granules. The dehydrogenation of butylene to butadiene on an α-Al2O3 membrane with selective hydrogen removal from the reaction zone has made it possible to raise the 1,3-butadiene output from 16.5 to 22.6 L/(h gact. comp.), with the degree of ultrapure hydrogen extraction reaching ~16%. After the experiment was run for 20 h, no decrease in the catalytic activity of the system was detected, as distinct from commercial solutions, in which a regeneration step is necessary every 8–15 min.
Interconversion between γ-valerolactone and pentenoic acid combined with decarboxylation to form butene over silica/alumina
Bond, Jesse Q.,Wang, Dong,Alonso, David Martin,Dumesic, James A.
, p. 290 - 299 (2011)
Reaction kinetic studies were carried out of the reversible interconversion between γ-valerolactone (GVL) and pentenoic acid (PEA) combined with the irreversible decarboxylation of both species to form butene and CO2 over a SiO2/Al2O3 catalyst at pressures from atmospheric to 36 bar, temperatures from 498 to 648 K, different concentrations of GVL and PEA, as well as in the presence of water. The catalyst exhibited reversible deactivation within the initial 24 h on stream (losing about 50% of the initial catalytic activity), followed by a slower rate of deactivation of roughly 0.4-0.5% per hour on stream. Decarboxylation of γ-valerolactone, producing equimolar quantities of butene and CO2, may possibly occur by two distinct pathways: a direct route from the lactone and an indirect route from PEA. 1-butene is the primary product of decarboxylation, formed via β-scission of intermediate carbenium ions. The apparent activation barrier for decarboxylation of GVL (175 kJ mol-1) is higher than for decarboxylation of PEA (142 kJ mol-1). A simple kinetic model with rate expressions accounting for adsorption and unimolecular surface reactions of GVL and PEA is sufficient to describe the trends measured for the rates of GVL ring opening to PEA, GVL decarboxylation, PEA cyclization to GVL, and PEA decarboxylation at different reaction conditions.
Nickle-Schiff base covalently grafted to UiO-66-NH2 as heterogeneous catalyst for ethylene oligomerization
Chen, Liduo,Jin, Rui,Li, Cuiqin,Mao, Guoliang,Tan, Jinyan,Wang, Jun,Zhang, Na
, (2021/11/27)
Metal organic frameworks (MOFs) UiO-66-NH2 had been modified by reaction of pyridine-2-carboxaldehyde with the amino groups to form a pyridineimine that act as ligand of metal Ni. The UiO-66-NH2 grafted pyridineimine nickel catalyst of post synthetic modification was assessed by fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), scanning electron microscope (SEM), inductively coupled plasma mass spectrometry (ICP-MS) and nitrogen adsorption–desorption, and the catalytic performance of the UiO-66-NH2 grafted pyridineimine nickel catalyst in ethylene oligomerization was investigated. The results showed that the catalyst structure, reaction temperature, Al/Ni molar ratio and reaction pressure had a significant effect on the catalytic activity and products selectivity. The catalytic activity of 3.76 × 105 g·(mol Ni·h)?1 and 75.94% selectivity of butene were obtained when the reaction temperature was 25 ℃, Al/Ni molar ratio was 1000 and reaction pressure was 1.2 MPa.
Ethylene oligomerization with 2-hydroxymethyl-5,6,7-trihydroquinolinyl-8-ylideneamine-Ni(II) chlorides
Xu, Lei,Li, Jiaxin,Lin, Wenhua,Ma, Yanping,Hu, Xinquan,Flisak, Zygmunt,Sun, Wen-Hua
, (2021/02/16)
A series of Ni complexes of the general formula [2-(MeOH)-8-{N(Ar)}C9H8N]NiCl2, where Ar = 2,6-Me2C6H3 in Ni1; 2,6-Et2C6H3 in Ni2; 2,6-i-Pr2C6H3 in Ni3; 2,4,6-Me3C6H2 in Ni4; 2,6-Et2-4-MeC6H2 in Ni5 and 2,4,6-t-Bu3C6H2 in Ni6 has been synthesized and characterized by elemental analysis and IR spectroscopy. On activation with MMAO or Et2AlCl, these complexes showed high activity in ethylene oligomerization, reaching 2.23 × 106 g·mol–1 (Ni) h–1 at 30 °C with the Al/Ni ratio of 5500 and 9.11 × 105 g·mol–1 (Ni) h–1 with the Al/Ni of 800, respectively. Moreover, the content of α-C4 indicated high selectivity exceeding 99% in the Ni/Et2AlCl system. Comparing with the previous report by our group, this work discloses higher activity, presumably due to the substituent at the 2-position within the ligand influencing the steric hindrance around the metal atom. Furthermore, it is worth noting that the branched alkenes have been observed (iso-C6: 35.3 – 57.2%) in the oligomerization products.
Regioselective Gas-Phase n-Butane Transfer Dehydrogenation via Silica-Supported Pincer-Iridium Complexes
Sheludko, Boris,Castro, Cristina F.,Khalap, Chaitanya A.,Emge, Thomas J.,Goldman, Alan S.,Celik, Fuat E.
, p. 407 - 415 (2020/12/01)
The production of olefins via on-purpose dehydrogenation of alkanes allows for a more efficient, selective and lower cost alternative to processes such as steam cracking. Silica-supported pincer-iridium complexes of the form [(≡SiO?R4POCOP)Ir(CO)] (R4POCOP=κ3-C6H3-2,6-(OPR2)2) are effective for acceptorless alkane dehydrogenation, and have been shown stable up to 300 °C. However, while solution-phase analogues of such species have demonstrated high regioselectivity for terminal olefin production under transfer dehydrogenation conditions at or below 240 °C, in open systems at 300 °C, regioselectivity under acceptorless dehydrogenation conditions is consistently low. In this work, complexes [(≡SiO?tBu4POCOP)Ir(CO)] (1) and [(≡SiO?iPr4PCP)Ir(CO)] (2) were synthesized via immobilization of molecular precursors. These complexes were used for gas-phase butane transfer dehydrogenation using increasingly sterically demanding olefins, resulting in observed selectivities of up to 77 %. The results indicate that the active site is conserved upon immobilization.
