Olefins In Ionic Liquids Research Articles

Cr-catalysed ethylene dimerization in an ionic liquid-organic solvent biphasic system with perfect 1-butene selectivity.

Cr-catalyzed ionic liquid-organic biphasic ethylene dimerization was realized with 100% 1-butene selectivity. The perfect α-olefin selectivity can be rationalized in terms of the poor solubility of the oligomerized long-chain olefins in ionic liquids, and enables the establishment of a dimerization process without any complicated and energy-intensive catalyst and byproduct separation processes.

Ru-Catalyzed Repetitive Batch Borylative Coupling of Olefins in Ionic Liquids or Ionic Liquids/scCO2 Systems

The first, recyclable protocol for the selective synthesis of (E)-alkenyl boronates via borylative coupling of olefins with vinylboronic acid pinacol ester in monophasic (cat@IL) or biphasic (cat@IL/scCO2) systems is reported in this article. The efficient immobilization of [Ru(CO)Cl(H)(PCy3)2] (1 mol%) in [EMPyr][NTf2] and [BMIm][OTf] with the subsequent extraction of products with n-heptane permitted multiple reuses of the catalyst without a significant decrease in its activity and stability (up to 7 runs). Utilization of scCO2 as an extractant enabled a significant reduction in the amount of catalyst leaching during the separation process, compared to extraction with n-heptane. Such efficient catalyst immobilization allowed an intensification of the processes in terms of its productivity, which was indicated by high cumulative TON values (up to 956) in contrast to the traditional approach of applying volatile organic solvents (TON = ~50–100). The reaction was versatile to styrenes with electron-donating and withdrawing substituents and vinylcyclohexane, generating unsaturated organoboron compounds, of which synthetic utility was shown by the direct transformation of extracted products in iododeborylation and Suzuki coupling processes. All synthesized compounds were characterized using 1H, 13C NMR and GC-MS, while leaching of the catalyst was detected with ICP-MS.

A Homogeneous Chiral Manganese(III)–Salphe Catalyst for Enantioselective Epoxidation of Olefins

A new chiral Mn(III)–Salphe catalyst was synthesized from natural amino acid (R)-phenylalanine and 3,5-di-tert-butyl-hydroxybenzaldehyde and applied to the asymmetric epoxidations of unfunctionalized olefins in ionic liquids. Satisfactory enantioselectivities (79% < ee < 93%) and good yields were achieved when NaClO was used as oxidant. We found that both the pH value (11.3) and reaction temperature (15 °C) were crucial for the epoxidation reactions. In our reaction system, NH4OAc was unnecessary. We proposed that alcoholic hydroxyls in the Mn(III)–Salphe compound played the role of axial ligand. However, the reaction time was longer than when using Jacobsen's catalyst because of the structure of the Mn(III)–Salphe compound, in which coordination geometries by the two alcoholic hydroxyls with certain angles affected the substrate approaching the Mn(V) = 0 center. The chiral ligand was characterized by the combination of infrared, ultraviolet, and visible spectra and 1H NMR. Supplemental materials are available for this article. Go to the publisher's online edition of Synthetic Communications® to view the free supplemental file.

Asymmetric Catalytic Hydroamination of Activated Olefins in Ionic Liquids.

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Asymmetric Catalytic Hydroamination of Activated Olefins in Ionic Liquids

AbstractThe addition of a series of both aliphatic and aromatic amines to electron‐poor olefins was investigated using [Ni(Pigiphos)(THF)]2+ as catalyst (with different counterions) in various ionic liquids based on imidazolium‐ and picolinium‐salt derivatives. The catalysts gave rise to selectivities comparable to those obtained when the reaction was conducted in neat organic solvents (ee up to 66%), but significant higher activities, with a total turnover number (TON) of up to 300.

Highly Regioselective Heck Reactions of Heteroaryl Halides with Electron‐Rich Olefins in Ionic Liquid.

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Clean Osmium‐Catalyzed Asymmetric Dihydroxylation of Olefins in Ionic Liquids and Supercritical CO2 Product Recovery.

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Highly regioselective Heck reactions of heteroaryl halides with electron-rich olefins in ionic liquid

Palladium-catalyzed Heck reactions of the heteroaryl halides, halopyridines, bromoquinoline and bromothiophenes, with the electron-rich olefins vinyl ethers and allyl alcohol were shown to give essentially only the branched olefins in an imidazolium ionic liquid, whereas in molecular solvents a mixture of regioisomers was formed. The method obviates the need for aryl triflates and stoichiometric inorganic salt additives, providing an easy entry to functionalized heteroaromatics incorporating acetyl and 2-allyl alcohol functionalities.

Osmium-catalyzed asymmetric dihydroxylation of olefins in ionic liquids

Effective osmium-catalyzed asymmetric dihydroxylation was observed with 1,4-bis(9- O -diquininyl)phthalazine, (DQ) 2 PHAL, as the chiral ligand in the ionic liquid, 1- n -butyl-3-methylimidazolium hexafluorophosphate [bmim][PF 6 ]. It was shown that the ligand undergoes dihydroxylation during the reaction, affording a more polar ligand which remains in the ionic liquid phase, when the latter is extracted with diethyl ether, thus facilitating catalyst recycling. In contrast, when 1,4-bis(9- O -dihydroquininyl)phthalazine, (DHQ) 2 PHAL, which cannot undergo dihydroxylation, was used as the chiral ligand, the catalyst was extracted into the organic layer. The osmium-catalyzed hydroxylation of trans-stilbene in aqueous acetone-ionic liquid medium was enantioselective (85% ee) in the presence of the chiral ligand (D2OHQ) 2 PHAL. The chiral ligand was formed from a precursor under the reaction conditions and was recycled together with the ionic liquid.

Clean osmium-catalyzed asymmetric dihydroxylation of olefins in ionic liquids and supercritical CO2 product recovery

The combination of ionic liquids (ILs) as solvents in the asymmetric Sharpless dihydroxylation (AD) with the use of scCO(2) in the separation process allows a very simple, efficient, clean and robust system for the reuse of the AD catalytic system, which also does not need the use of organic solvents either for the reaction or for the separation of products and allows the isolation of the diol, in high yield and enantiomeric excess and basically without contamination with osmium.

ChemInform Abstract: OsO4‐Catalyzed Dihydroxylation of Olefins in Ionic Liquid [emim]BF4: A Recoverable and Reusable Osmium.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.