13269-52-8Relevant academic research and scientific papers
METAL COMPLEXES IN CATALYTIC CONVERSION OF OLEFINS. 3. CATALYTIC DIMERIZATION OF ETHYLENE AND PROPYLENE BY Ni(PPh3)n-Et3Al2Cl3 SYSTEM
Furman, D. B.,Kudryashev, A. V.,Ivanov, A. O.,Pogorelov, A. G.,Yanchevskaya, T. V.,Bragin, O. V.
, p. 444 - 447 (1990)
The Ni(PPh3)n-Et3Al2Cl3 catalytic system was found to be most effective for the dimerization of ethylene and propylene when the ligands Bu3PO and (BuO)2-PNEt2 were used in the Ni complex.For propylene dimerization in the liquid phase, the yield was 54 kmole/mole Nih at 40 - 55 deg C.Using mathematical planing methods for the experiments the optimum conditions range for the formation of hexanes was found, in which selectivity for dimerization reached 85-96percent at 80-90percent conversion.
Influence of increasing steric demand on isomerization of terminal alkenes catalyzed by bifunctional ruthenium complexes
Smarun, Alexey V.,Shahreel, Wahyu,Pramono, Steven,Koo, Shin Yi,Tan, Lai Yoong,Ganguly, Rakesh,Vidovi?, Dragoslav
, p. 1 - 9 (2017)
Preparation of a series of cyclopentadienyl- and imidazolyl-phosphine-containing Ru-based complexes bearing a different degree of the Cp-ring methylation has been attempted. According to experimental and structural data the steric factors prevented the formation of the last complex in the series that contains permethylated Cp ring. These complexes were then subjected to alkene isomerization using 1-hexene. The rate of isomerization decreased, in general, with the increase in the Cp-ring methylation suggesting that the initial alkene coordination and/or imidazolyl N decoordination steps are restricted in the overall mechanism.
Isomerization of Olefins Catalyzed by the Hexaaquaruthenium(2+) Ion
Karlen, Thomas,Ludi, Andreas
, p. 1604 - 1606 (1992)
Isomerization of olefins, in particular the useful transformation of allyl to vinyl ethers is catalyzed by the hexaaquaruthenium(2+) ion, producing the (E)-isomers under mild conditions.
Immobilized Platinum Hydride Species as Catalysts for Olefin Isomerizations and Enyne Cycloisomerizations
Bauer, Matthias,Cronin, Steve P.,Dyballa, Michael,Estes, Deven P.,Li, Zheng,Maier, Sarah,Nowakowski, Michal,Vu Dinh, Manh-Anh
, p. 1751 - 1757 (2021)
Platinum hydride species catalyze a number of interesting organic reactions. However, their reactions typically involve the use of high loadings of noble metal and are difficult to recycle, making them somewhat unsustainable. We have synthesized surface-immobilized Pt-H species via oxidative addition of surface OH groups to Pt(PtBu3)2 (1), a rarely used immobilization technique in surface organometallic chemistry. The hydride species thus made were characterized by infrared, magic-angle spinning nuclear magnetic resonance, and X-ray absorption spectroscopies and catalyzed both olefin isomerization and cycloisomerization of a 1,6 enyne (5) with a high selectivity and low Pt loading.
Rhodium(III) Catalyzed Solvent-Free Tandem Isomerization–Hydrosilylation From Internal Alkenes to Linear Silanes
Azpeitia, Susan,Garralda, María A.,Huertos, Miguel A.
, p. 1901 - 1905 (2017)
The selective synthesis of linear silanes from internal alkenes or alkene mixtures is reported. Unsaturated 16 electrons hydrido–silyl–RhIII complexes are efficient catalysts for a tandem catalytic alkene isomerization–hydrosilylation reaction at room temperature under solvent-free conditions. Such a process would be of value to the chemical industry, as mixtures of internal aliphatic olefins are substantially cheaper and more readily available than the pure terminal isomers.
Metathesis of hex-1-ene in ionic liquids catalyzed by WCl6
Vasnev,Greish,Kustov
, p. 2187 - 2191 (2004)
Metathesis of hex-1-ene in ionic liquids catalyzed by WCl6 was studied. The metathesis is preceded by isomerization of hex-1-ene to hex-2-ene, from which the main reaction product, viz., oct-4-ene, is derived. The WCl 6-1-butyl-3-methylimidazolium tetrafluoroborate (BMIM·BF 4) system efficiently catalyzes metathesis of linear olefin, the ionic liquid serving as the reaction medium by forming a stable homogeneous catalytic system with WCl6. The yields of the metathesis products increase with increasing reaction temperature. The addition of tin-containing promoters leads to a substantial increase in the reaction rate. In the WCl 6-BMIM·BF4-SnBu4 system, the selectivity of the formation of oct-4-ene is significantly enhanced.
Catalyst versus Substrate Control of Forming (E)-2-Alkenes from 1-Alkenes Using Bifunctional Ruthenium Catalysts
Paulson, Erik R.,Delgado, Esteban,Cooksy, Andrew L.,Grotjahn, Douglas B.
, p. 1672 - 1682 (2018)
Here we examine in detail two catalysts for their ability to selectively convert 1-alkenes to (E)-2-alkenes while limiting overisomerization to 3- or 4-alkenes. Catalysts 1 and 3 are composed of the cations CpRu(κ2-PN)(CH3CN)+ and Cp?Ru(κ2-PN)+, respectively (where PN is a bifunctional phosphine ligand), and the anion PF6-. Kinetic modeling of the reactions of six substrates with 1 and 3 generated first- and second-order rate constants k1 and k2 (and k3 when applicable) that represent the rates of reaction for conversion of 1-alkene to (E)-2-alkene (k1), (E)-2-alkene to (E)-3-alkene (k2), and so on. The k1:k2 ratios were calculated to produce a measure of selectivity for each catalyst toward monoisomerization with each substrate. The k1:k2 values for 1 with the six substrates range from 32 to 132. The k1:k2 values for 3 are significantly more substrate-dependent, ranging from 192 to 62 000 for all of the substrates except 5-hexen-2-one, for which the k1:k2 value was only 4.7. Comparison of the ratios for 1 and 3 for each substrate shows a 6-12-fold greater selectivity using 3 on the three linear substrates as well as a >230-fold increase for 5-methylhex-1-ene and a 44-fold increase for a silyl-protected 4-penten-1-ol substrate, which are branched three and five atoms away from the alkene, respectively. The substrate 5-hexen-2-one is unique in that 1 was more selective than 3; NMR analysis suggested that chelation of the carbonyl oxygen can facilitate overisomerization. This work highlights the need for catalyst developers to report results for catalyzed reactions at different time points and shows that one needs to consider not only the catalyst rate but also the duration over which a desired product (here the (E)-2-alkene) remains intact, where 3 is generally superior to 1 for the title reaction.
The Reactions of Hexyl Ions on USHY
Wojciechowski, B. W.,Zhao, Y.-X.
, p. 239 - 253 (1995)
We have examined the behavior of C6 carbenium ions in the cracking of 2-methylpentane on USHY.We find that at 400 deg C, hexyl carbenium ions undergo hydride addition from the feed 10 times faster than proton release to the Broensted base.This makes the isomerization of the feed a much faster reaction than the production of olefins with the same carbon number.We also find that proton release from a C6 ion to the Broensted base requires a higher activation energy than a hydride transfer from the feed to the same ion.At high temperatures isomerization is therefore reduced with respect to olefin production.The presence of steam in the cracking mixture weakens the Broensted base, and reduces the rates of all reactions but encourages hydride transfer over proton release.This enhances the formation of paraffinic isomers of the feed.At the low steam dilution ratio of 0.07 mol/mol, hydride transfer in 2-methylpentane is as much as 18 times faster than proton release, resulting in a highly isomerized, highly saturated product.The full picture of individual ion fates is presented and gives an important insight into the causes underlying cracking selectivity and the possible methods for its control.
Highly Stereoselective Isomerization of Monosubstituted 1-Alkenes to (E)-2-Alkenes by Catalysis of (C5Me5)2TiCl2/NaC10H8
Akita, Munetaka,Yasuda, Hajime,Nagasuna, Kinya,Nakamura, Akira
, p. 554 - 558 (1983)
The catalyst systems which consist of MCl2(C5R5)2(M=Ti, Zr; R=H, CH3)/NaC10H8, i-C3H7MgBr, n-C4H9Li or LiAlH4 in 1:2 ratio were highly effective for the stereoselective isomerization of monosubstituted 1-alkenes to (E)-2-alkenes.Unconjugated dienes were converted to (E)- or (E,E)-dienes.The catalysis of (C5Me5)TiCl2/NaC10H8 was extremely high and resulted in the complete isomerization of 1-alkenes in >99percent stereoselectivity within a short period.The use of the bulky C5Me5 ligand is essential to find out the excellent stereoselectivity.Systems, (C5H5)2TiCl2/NaC10H8 and (C5H5)2TiCl2/i-C3H7MgBr showed less selectivity and the catalysis of the corresponding zirconium systems was very poor irrespective of the reducing agents and substrates.
A warning on the use of radical traps as a test for radical mechanisms: They react with palladium hydrido complexes
Albeniz, Ana C.,Espinet, Pablo,Lopez-Fernandez, Raquel,Sen, Ayusman
, p. 11278 - 11279 (2002)
Typical radical traps (galvinoxyl, TEMPO, DPPH) react with palladium hydrides, sometimes at rates competitive with those of palladium hydride catalyzed reactions that follow an insertion mechanism (for example, alkene isomerization). Thus, positive results for radical reaction tests can be misleading. The complexes with more polarizable (neutral complexes rather than cationic) and more accessible hydrides, and the less sterically protected radical traps, react faster. Copyright
