- Hydroxycarbonylation of isobutylene in the presence of the palladium acetylacetonate-triphenylphosphine-p-toluenesulfonic acid catalyst system
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The reaction of isobutylene hydroxycarbonylation with carbon monoxide and an alcohol (ethanol, 1-menthol) in the presence of the palladium acetylacetonate-triphenylphosphine-p-toluenesulfonic acid catalytic system was investigated. It was shown that the reaction proceeds regioselectively with the formation of linear products (ethyl isovalerate, 1-menthyl isovalerate). The optimum conditions for running the process were found, at which the yield of the main products is 67-79%.
- Suerbaev,Chepaikin,Zhaksylykova, G. Zh.,Kanybetov,Turkbenov,Abyzbekova
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- Copper-catalyzed conjugate addition of organomagnesium reagents to α,β-ethylenic esters: A simple high yield procedure
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The conjugate addition of organomagnesium reagents to α, β-ethylenic esters is performed in THF, at room temperature (30 min to 1.5 h), in the presence of CuCl (3%) and Me3SiCl (1.2 eq.). Good yields of 1,4-addition products are obtained according to this very simple procedure.
- Cahiez, Gerard,Alami, Mouad
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- REACTION OF ORGANOMETALLIC REAGENTS WITH TRIETHOXYACETONITRILE. A NEW AND SHORT SYNTHESIS OF α-KETOESTERS.
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Grignard reagents react with triethoxyacetonitrile to give esters, while organolithium reagents provide α-ketoesters in excellent yields.
- Axiotis, Georges P.
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- Catalytic hydrogenation activity and electronic structure determination of bis(arylimidazol-2-ylidene)pyridine Cobalt Alkyl and Hydride Complexes
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The bis(arylimidazol-2-ylidene)pyridine cobalt methyl complex, ( iPrCNC)CoCH3, was evaluated for the catalytic hydrogenation of alkenes. At 22 C and 4 atm of H2 pressure, ( iPrCNC)CoCH3 is an effective precatalyst for the hydrogenation of sterically hindered, unactivated alkenes such as trans-methylstilbene, 1-methyl-1-cyclohexene, and 2,3-dimethyl-2-butene, representing one of the most active cobalt hydrogenation catalysts reported to date. Preparation of the cobalt hydride complex, (iPrCNC)CoH, was accomplished by hydrogenation of (iPrCNC)CoCH3. Over the course of 3 h at 22 C, migration of the metal hydride to the 4-position of the pyridine ring yielded (4-H2-iPrCNC)CoN2. Similar alkyl migration was observed upon treatment of (iPrCNC)CoH with 1,1-diphenylethylene. This reactivity raised the question as to whether this class of chelate is redox-active, engaging in radical chemistry with the cobalt center. A combination of structural, spectroscopic, and computational studies was conducted and provided definitive evidence for bis(arylimidazol-2- ylidene)pyridine radicals in reduced cobalt chemistry. Spin density calculations established that the radicals were localized on the pyridine ring, accounting for the observed reactivity, and suggest that a wide family of pyridine-based pincers may also be redox-active.
- Yu, Renyuan Pony,Darmon, Jonathan M.,Milsmann, Carsten,Margulieux, Grant W.,Stieber, S. Chantal E.,Debeer, Serena,Chirik, Paul J.
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- Hydroesterification of tert-butyl alcohol in room temperature ionic liquids
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Hydroesterification of tert-butyl alcohol with ethanol catalyzed by transition metal triphenylphosphine complexes in the presence of p-toluenesulfonic acid was investigated using room temperature ionic liquids as the reaction medium at 373-413 K and 3-6 MPa of CO. In comparison with the organic solvents as reaction medium, higher conversion was achieved and ethyl tert-valerate could be directly formed in the ionic liquid medium. The products could be separated from the ionic liquids easily due to their immiscibility in this medium.
- Qiao, Kun,Deng, Youquan
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- Green syntheses of biobased solvents
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The design of bioproducts implies the use of renewable carbon but also the conversion of this carbon through clean processes. This step is often a limiting one if we consider the whole life cycle "from the raw materials to the fate of the products". We proposed, in this work, to adapt conventional methods to the conversion of a natural raw material, the fusel oil, a co-product generated by ethanol industry to prepare acetates, carbonates and isovalerates. Selected conditions are compared to conventional routes to quantify their ecoefficiency and to check their potential development for the preparation of new biosolvents. In another step, we have calculated the volatile organic compound amount emitted during the production of a new cosmetic formulation using the fusel oil derivatives. This complete but simple example shows how to identify a real competitive alternative to the usual production chains.
- Bandres, Matthieu,De Caro, Pascale,Thiebaud-Roux, Sophie,Borredon, Marie-Elisabeth
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- Silylene-Bridged Tetranuclear Palladium Cluster as a Catalyst for Hydrogenation of Alkenes and Alkynes
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A planar tetranuclear palladium cluster was obtained from the reaction of a cyclotetrasilane with [Pd(CNtBu)2]3. Single-crystal X-ray diffraction analysis and DFT calculations revealed that the tetranuclear framework of the cluster was supported effectively by the bridging organosilylene ligand. Although [Pd(CNtBu)2]3 as well as mononuclear palladium bis(silyl) complex, cis-Pd(SiMePh2)2(CNtBu)2, do not act as the effective catalyst, the planar tetranuclear palladium cluster acts as an efficient catalyst for the hydrogenation of alkenes and alkynes including sterically hindered tri- and tetra-substituted alkenes.
- Yanagisawa, Chikako,Yamazoe, Seiji,Sunada, Yusuke
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p. 169 - 173
(2020/10/29)
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- Nuclearity expansion in Pd clusters triggered by the migration of a phenyl group in cyclooligosilanes
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Heptanuclear palladium clusters with six palladium atoms in a planar arrangement were obtained from the reaction of [Pd(CNtBu)2]3with Ph-substituted cyclotetrasilane or cyclopentasilaneviathe migration of a phenyl group. The molecular structures of these clusters as well as those of two possible intermediates were determined by single-crystal X-ray diffraction analyses.
- Shimamoto, Kento,Sunada, Yusuke
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supporting information
p. 7649 - 7652
(2021/08/09)
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- Photoinduced Hydrocarboxylation via Thiol-Catalyzed Delivery of Formate across Activated Alkenes
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Herein we disclose a new photochemical process to prepare carboxylic acids from formate salts and alkenes. This redox-neutral hydrocarboxylation proceeds in high yields across diverse functionalized alkene substrates with excellent regioselectivity. This operationally simple procedure can be readily scaled in batch at low photocatalyst loading (0.01% photocatalyst). Furthermore, this new reaction can leverage commercially available formate carbon isotologues to enable the direct synthesis of isotopically labeled carboxylic acids. Mechanistic studies support the working model involving a thiol-catalyzed radical chain process wherein the atoms from formate are delivered across the alkene substrate via CO2?- as a key reactive intermediate.
- Alektiar, Sara N.,Wickens, Zachary K.
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supporting information
p. 13022 - 13028
(2021/09/03)
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- Environmentally responsible, safe, and chemoselective catalytic hydrogenation of olefins: ppm level Pd catalysis in recyclable water at room temperature
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Textbook catalytic hydrogenations are typically presented as reactions done in organic solvents and oftentimes under varying pressures of hydrogen using specialized equipment. Catalysts new and old are all used under similar conditions that no longer reflect the times. By definition, such reactions are both environmentally irresponsible and dangerous, especially at industrial scales. We now report on a general method for chemoselective and safe hydrogenation of olefins in water using ppm loadings of palladium from commercially available, inexpensive, and recyclable Pd/C, together with hydrogen gas utilized at 1 atmosphere. A variety of alkenes is amenable to reduction, including terminal, highly substituted internal, and variously conjugated arrays. In most cases, only 500 ppm of heterogeneous Pd/C is sufficient, enabled by micellar catalysis used in recyclable water at room temperature. Comparison with several newly introduced catalysts featuring base metals illustrates the superiority of chemistry in water.
- Gallou, Fabrice,Gao, Eugene S.,Lipshutz, Bruce H.,Takale, Balaram S.,Thakore, Ruchita R.
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supporting information
p. 6055 - 6061
(2020/10/14)
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- Bidentate NHC-Cobalt Catalysts for the Hydrogenation of Hindered Alkenes
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Herein, we report a series of easily accessible bidentate N-heterocyclic carbene (NHC) cobalt catalysts, which enable the hydrogenation of hindered alkenes under mild conditions. The four-coordinated bidentate NHC-Co(II) complexes were characterized by X-ray diffraction, elemental analysis, ESI-HRMS, and magnetic moment measurements, revealing a distorted-tetrahedral geometry and a high-spin configuration of the metal center. The activity of the in situ formed catalytic system, which was obtained from easily available NHC precursors, CoCl2, and NaHBEt3, was identical with those of well-defined NHC-cobalt catalysts. This highlights the potential utility of this reaction system.
- Wei, Zeyuan,Wang, Yujie,Li, Yibiao,Ferraccioli, Raffaella,Liu, Qiang
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supporting information
p. 3082 - 3087
(2020/10/02)
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- Mononuclear iron complex and organic synthesis reaction using same
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A mononuclear iron bivalent complex having iron-silicon bonds, which is represented by formula (1), can exhibit an excellent catalytic activity in at least one reaction selected from three reactions, i.e., a hydrosilylation reaction, a hydrogenation reaction and a reaction for reducing a carbonyl compound. (In the formula, R1 to R6 independently represent a hydrogen atom, an alkyl group which may be substituted by X, or the like; X represents a halogen atom, or the like; L1 represents at least one two-electron ligand selected from an isonitrile ligand, an amine ligand, an imine ligand, a nitrogenated heterocyclic ring, a phosphine ligand, a phosphite ligand and a sulfide ligand, wherein, when multiple L1's are present, two L1's may be bonded to each other; L2 represents a two-electron ligand that is different from a CO ligand or the above-mentioned L1, wherein, when multiple L2's are present, two L2's may be bonded to each other; and m1 represents an integer of 1 to 4 and m2 represents an integer of 0 to 3, wherein the sum total of m1 and m2 (i.e., m1+m2) satisfies 3 or 4.)
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Page/Page column 31; 34
(2019/08/20)
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- Amine-Borane Dehydrogenation and Transfer Hydrogenation Catalyzed by α-Diimine Cobaltates
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Anionic α-diimine cobalt complexes, such as [K(thf)1.5{(DippBIAN)Co(η4-cod)}] (1; Dipp=2,6-diisopropylphenyl, cod=1,5-cyclooctadiene), catalyze the dehydrogenation of several amine-boranes. Based on the excellent catalytic properties, an especially effective transfer hydrogenation protocol for challenging olefins, imines, and N-heteroarenes was developed. NH3BH3 was used as a dihydrogen surrogate, which transferred up to two equivalents of H2 per NH3BH3. Detailed spectroscopic and mechanistic studies are presented, which document the rate determination by acidic protons in the amine-borane.
- Maier, Thomas M.,Sandl, Sebastian,Shenderovich, Ilya G.,Jacobi von Wangelin, Axel,Weigand, Jan J.,Wolf, Robert
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supporting information
p. 238 - 245
(2019/01/04)
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- Cobalt-Catalyzed Hydrogenations via Olefin Cobaltate and Hydride Intermediates
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Redox noninnocent ligands are a promising tool to moderate electron transfer processes within base-metal catalysts. This report introduces bis(imino)acenaphthene (BIAN) cobaltate complexes as hydrogenation catalysts. Sterically hindered trisubstituted alkenes, imines, and quinolines underwent clean hydrogenation under mild conditions (2-10 bar, 20-80 °C) by use of the stable catalyst precursor [(DippBIAN)CoBr2] and the cocatalyst LiEt3BH. Mechanistic studies support a homogeneous catalysis pathway involving alkene and hydrido cobaltates as active catalyst species. Furthermore, considerable reaction acceleration by alkali cations and Lewis acids was observed. The dinuclear hydridocobaltate anion with bridging hydride ligands was isolated and fully characterized.
- Sandl, Sebastian,Maier, Thomas M.,Van Leest, Nicolaas P.,Kr?ncke, Susanne,Chakraborty, Uttam,Demeshko, Serhiy,Koszinowski, Konrad,De Bruin, Bas,Meyer, Franc,Bodensteiner, Michael,Herrmann, Carmen,Wolf, Robert,Von Jacobi Wangelin, Axel
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p. 7596 - 7606
(2019/08/20)
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- Olefin-Stabilized Cobalt Nanoparticles for C=C, C=O, and C=N Hydrogenations
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The development of cobalt catalysts that combine easy accessibility and high selectivity constitutes a promising approach to the replacement of noble-metal catalysts in hydrogenation reactions. This report introduces a user-friendly protocol that avoids complex ligands, hazardous reductants, special reaction conditions, and the formation of highly unstable pre-catalysts. Reduction of CoBr2 with LiEt3BH in the presence of alkenes led to the formation of hydrogenation catalysts that effected clean conversions of alkenes, carbonyls, imines, and heteroarenes at mild conditions (3 mol % cat., 2–10 bar H2, 20–80 °C). Poisoning studies and nanoparticle characterization by TEM, EDX, and DLS supported the notion of a heterotopic catalysis mechanism.
- Sandl, Sebastian,Schwarzhuber, Felix,P?llath, Simon,Zweck, Josef,Jacobi von Wangelin, Axel
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supporting information
p. 3403 - 3407
(2018/02/13)
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- Disilaruthena- and Ferracyclic Complexes Containing Isocyanide Ligands as Effective Catalysts for Hydrogenation of Unfunctionalized Sterically Hindered Alkenes
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Disilaferra- and disilaruthenacyclic complexes containing mesityl isocyanide as a ligand, 3′ and 4′, were synthesized and characterized by spectroscopy and crystallography. Both 3′ and 4′ showed excellent catalytic activity for the hydrogenation of alkenes. Compared with iron and ruthenium carbonyl analogues, 1′ and 2′, the isocyanide complexes 3′ and 4′ were more robust under the hydrogenation conditions, and were still active even at higher temperatures (～80 °C) under high hydrogen pressure (～20 atm). The iron complex 3′ exhibited the highest catalytic activity toward hydrogenation of mono-, di-, tri-, and tetrasubstituted alkenes among currently reported iron catalysts. Ruthenium complex 4′ catalyzed hydrogenation under very mild conditions, such as room temperature and 1 atm of H2. The remarkably high catalytic activity of 4′ for hydrogenation of unfunctionalized tetrasubstituted alkenes was especially notable, because it was comparable to the activity of iridium complexes reported by Crabtree and Pfaltz, which are catalysts with the highest activity in the literature. DFT calculations suggested two plausible catalytic cycles, both of which involved activation of H2 assisted by the metal-silicon bond through σ-bond metathesis of late transition metals (oxidative hydrogen migration). The linear structure of M C≡N - C (ipso carbon of the mesityl group) played an essential role in the efficient hydrogenation of sterically hindered tetrasubstituted alkenes.
- Sunada, Yusuke,Ogushi, Hajime,Yamamoto, Taiji,Uto, Shoko,Sawano, Mina,Tahara, Atsushi,Tanaka, Hiromasa,Shiota, Yoshihito,Yoshizawa, Kazunari,Nagashima, Hideo
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supporting information
p. 4119 - 4134
(2018/03/29)
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- A Co2B Mediated NaBH4 Reduction Protocol Applicable to a Selection of Functional Groups in Organic Synthesis
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A high-yielding and high-rate reduction method that operates with alkenes, alkynes, azides, nitriles, and nitroarenes was developed and optimized. The method makes use of sodium borohydride reduction of CoSO4 under release of hydrogen along with the formation of Co2B as a nanoparticle material. The produced Co2B activates the various functional groups for hydride reduction. The protocol was proven to operate with an assortment of functional groups to provide good to excellent yields. Furthermore, the reduction method was successfully adapted, implemented, and developed for a continuous flow approach using the multi-jet oscillating disk (MJOD) flow reactor platform at atmospheric pressure.
- Lundevall, Frida Johanne,Elumalai, Vijayaragavan,Drageset, Audun,Totland, Christian,Bj?rsvik, Hans-René
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supporting information
p. 3416 - 3425
(2018/07/29)
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- Transfer Hydrogenation of Alkenes Using Ethanol Catalyzed by a NCP Pincer Iridium Complex: Scope and Mechanism
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The first general catalytic approach to effecting transfer hydrogenation (TH) of unactivated alkenes using ethanol as the hydrogen source is described. A new NCP-type pincer iridium complex (BQ-NCOP)IrHCl containing a rigid benzoquinoline backbone has been developed for efficient, mild TH of unactivated C-C multiple bonds with ethanol, forming ethyl acetate as the sole byproduct. A wide variety of alkenes, including multisubstituted alkyl alkenes, aryl alkenes, and heteroatom-substituted alkenes, as well as O- or N-containing heteroarenes and internal alkynes, are suitable substrates. Importantly, the (BQ-NCOP)Ir/EtOH system exhibits high chemoselectivity for alkene hydrogenation in the presence of reactive functional groups, such as ketones and carboxylic acids. Furthermore, the reaction with C2D5OD provides a convenient route to deuterium-labeled compounds. Detailed kinetic and mechanistic studies have revealed that monosubstituted alkenes (e.g., 1-octene, styrene) and multisubstituted alkenes (e.g., cyclooctene (COE)) exhibit fundamental mechanistic difference. The OH group of ethanol displays a normal kinetic isotope effect (KIE) in the reaction of styrene, but a substantial inverse KIE in the case of COE. The catalysis of styrene or 1-octene with relatively strong binding affinity to the Ir(I) center has (BQ-NCOP)IrI(alkene) adduct as an off-cycle catalyst resting state, and the rate law shows a positive order in EtOH, inverse first-order in styrene, and first-order in the catalyst. In contrast, the catalysis of COE has an off-cycle catalyst resting state of (BQ-NCOP)IrIII(H)[O(Et)···HO(Et)···HOEt] that features a six-membered iridacycle consisting of two hydrogen-bonds between one EtO ligand and two EtOH molecules, one of which is coordinated to the Ir(III) center. The rate law shows a negative order in EtOH, zeroth-order in COE, and first-order in the catalyst. The observed inverse KIE corresponds to an inverse equilibrium isotope effect for the pre-equilibrium formation of (BQ-NCOP)IrIII(H)(OEt) from the catalyst resting state via ethanol dissociation. Regardless of the substrate, ethanol dehydrogenation is the slow segment of the catalytic cycle, while alkene hydrogenation occurs readily following the rate-determining step, that is, β-hydride elimination of (BQ-NCOP)Ir(H)(OEt) to form (BQ-NCOP)Ir(H)2 and acetaldehyde. The latter is effectively converted to innocent ethyl acetate under the catalytic conditions, thus avoiding the catalyst poisoning via iridium-mediated decarbonylation of acetaldehyde.
- Wang, Yulei,Huang, Zhidao,Leng, Xuebing,Zhu, Huping,Liu, Guixia,Huang, Zheng
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supporting information
p. 4417 - 4429
(2018/04/05)
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- Recyclable cobalt(0) nanoparticle catalysts for hydrogenations
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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.
- Büschelberger, Philipp,Reyes-Rodriguez, Efrain,Sch?ttle, Christian,Treptow, Jens,Feldmann, Claus,Jacobi Von Wangelin, Axel,Wolf, Robert
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p. 2648 - 2653
(2018/05/30)
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- Palladium-Catalyzed Carbonylation of sec- and tert-Alcohols
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A general palladium-catalyzed synthesis of linear esters directly from sec- and tert-alcohols is described. Compared to the classic Koch–Haaf reaction, which leads to branched products, this new transformation gives the corresponding linear esters in high yields and selectivity. Key for this protocol is the use of an advanced palladium catalyst system with L2 (pytbpx) as the ligand. A variety of aliphatic and benzylic alcohols can be directly used and the catalyst efficiency for the benchmark reaction is outstanding (turnover number up to 89 000).
- Dong, Kaiwu,Sang, Rui,Liu, Jie,Razzaq, Rauf,Franke, Robert,Jackstell, Ralf,Beller, Matthias
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supporting information
p. 6203 - 6207
(2017/05/22)
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- Alkene Hydrogenations by Soluble Iron Nanocluster Catalysts
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The replacement of noble metal technologies and the realization of new reactivities with earth-abundant metals is at the heart of sustainable synthesis. Alkene hydrogenations have so far been most effectively performed by noble metal catalysts. This study reports an iron-catalyzed hydrogenation protocol for tri- and tetra-substituted alkenes of unprecedented activity and scope under mild conditions (1–4 bar H2, 20 °C). Instructive snapshots at the interface of homogeneous and heterogeneous iron catalysis were recorded by the isolation of novel Fe nanocluster architectures that act as catalyst reservoirs and soluble seeds of particle growth.
- Gieshoff, Tim N.,Chakraborty, Uttam,Villa, Matteo,Jacobi von Wangelin, Axel
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supporting information
p. 3585 - 3589
(2017/03/21)
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- α-CAM mechanisms for the hydrogenation of alkenes by cis- and trans- disilametallacyclic carbonyl complexes (M = Fe, Ru, Os): Experimental and theoretical studies
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The hydrogenation of alkenes catalyzed by disilametallacyclic carbonyl complexes of iron, ruthenium or osmium was studied experimentally and theoretically. The disilaruthenacycle 2 with two CO ligands in the trans-configuration was prepared, characterized, and its ability to catalyze hydrogenation was studied. Similar to the corresponding iron analogue 1 in which the CO ligands are in the cis-configuration, 2 contains a H2MSi4 core with SiHSi SISHA (secondary interaction of silicon and hydrogen atoms) and catalyzed the hydrogenation of several alkenes under mild conditions. DFT calculations of 1 and 2 with cis- and trans-CO configurations (cis-1, trans-1, cis-2 and trans-2) revealed that the mechanism of ethylene hydrogenation comprises three catalytic cycles, and a key step involves the H-H bond of H2 being activated by an M-Si bond through oxidative hydrogen migration. These mechanisms are a variety of α-CAM (complex-assisted metathesis) mechanisms. Further calculations suggest that these catalytic cycles can apply to the catalytic hydrogenation of ethylene by osmium analogues of 1 and 2 (cis-3 and trans-3). Some of the elementary reactions in the cycles are dependent on the metal, and the osmium complexes show different performance from the iron and ruthenium analogues due to the characteristic natures of the third-row transition metals.
- Hoshi, Konoka,Tahara, Atsushi,Sunada, Yusuke,Tsutsumi, Hironori,Inoue, Ryoko,Tanaka, Hiromasa,Shiota, Yoshihito,Yoshizawa, Kazunari,Nagashima, Hideo
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p. 613 - 626
(2017/06/19)
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- Diverting Hydrogenations with Wilkinson's Catalyst towards Highly Reactive Rhodium(I) Species
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The addition of Barton's base has a dramatic effect on the classic rhodium(III)-mediated hydrogenations promoted by Wilkinson′s catalyst. Following the initial oxidative addition, a barrierless reductive elimination of HCl from the traditional rhodium(III) intermediates instantly produces a rhodium(I) monohydride species, which is remarkably reactive in the hydrogenation of several internal alkynes and functionalized trisubstituted alkenes. The direct formation of this species is unprecedented upon addition of molecular hydrogen and its catalytic potential has been hitherto barely explored.
- Perea-Buceta, Jesus E.,Fernández, Israel,Heikkinen, Sami,Axenov, Kirill,King, Alistair W. T.,Niemi, Teemu,Nieger, Martin,Leskel?, Markku,Repo, Timo
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supporting information
p. 14321 - 14325
(2016/01/25)
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- Catalytic functionalization of methane and light alkanes in supercritical carbon dioxide
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The development of catalytic methods for the effective functionalization of methane yet remains a challenge. The best system known to date is the so-called Catalytica Process based on the use of platinum catalysts to convert methane into methyl bisulfate with a TOF rate of 10-3 s. In this contribution, we report a series of silver complexes containing perfluorinated tris(indazolyl)borate ligands that catalyze the functionalization of methane into ethyl propionate upon reaction with ethyl diazoacetate (EDA) by using supercritical carbon dioxide (scCO2) as the reaction medium. The employment of this reaction medium has also allowed the functionalization of ethane, propane, butane, and isobutane.
- Fuentes, M. Angeles,Olmos, Andrea,Caballero, Ana,Perez, Pedro J.,Munoz, Bianca K.,Jacob, Kane,Etienne, Michel,Gonzalez-Nunez, M. Elena,Mello, Rossella,Asensio, Gregorio
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supporting information
p. 11013 - 11018,6
(2015/01/07)
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- Lipase-catalyzed synthesis of ethyl hexanoate in microemulsion system
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This paper studied lipase-catalyzed synthesis of ethyl hexanoate in dodecylbenzenesulfonic acid/isooctane/water microemulsion system. The effect of several parameters, such as w0 ([H2O]/[surfactant]) value, reaction time, reaction temperature, oil phase solvent, buffer solution pH value of microemulsion system on the esterification have been investigated. The results showed that the best experimental conditions for catalytic synthesis ethyl hexanoate were as follows: w0 = 4, reaction time 4 h, reaction temperature 40 °C, buffer solution pH 7. Under these conditions, the conversion of ethyl hexanoate can reach 98.5 %. Lipase-catalyzed synthesis of ethyl hexanoate in dodecylbenzenesulfonic acid inverse microemulsion system has triple mechanism, namely acid catalyzes, microemulsion catalyzes and enzyme catalyzes.
- Tan, Zhongqin,Han, Xiaoxiang,Hu, Xiaoli,Du, Huan,Bao, Xiuxiu
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p. 9675 - 9678
(2014/01/06)
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- Catalyst design for iron-promoted reductions: An iron disilyl-dicarbonyl complex bearing weakly coordinating η2-(H-Si) moieties
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Iron disilyl dicarbonyl complex 1, in which two H-Si moieties of the 1,2-bis(dimethylsilyl)benzene ligand were coordinated to the iron center in an η2-(H-Si) fashion, was synthesized by the reaction of (η4-C6H8)Fe(CO)3 with 2 equiv. of 1,2-bis(dimethylsilyl)benzene under photo-irradiation. Complex 1 demonstrated high catalytic activity toward the hydrogenation of alkenes, the hydrosilylation of alkenes and the reduction of carbonyl compounds.
- Sunada, Yusuke,Tsutsumi, Hironori,Shigeta, Keisuke,Yoshida, Ryota,Hashimoto, Toru,Nagashima, Hideo
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supporting information
p. 16687 - 16692
(2013/12/04)
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- Ester synthesis using Candida rugosa lipase immobilized on magnetic nanoparticles
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Magnetic nanoparticles were synthesized by co-precipitation under hydrothermal conditions. The average diameter of the magnetic nanoparticles was found to be in the range of 15 ± 5 nm with an average surface area of 112.15 m2 g-1. Immobilization of lipase on magnetite nanoparticles was confirmed by FTIR, differential scanning calorimetry and thermal gravimetric analysis. The activation energy of the free enzyme was 1.9-fold higher than that of the immobilized lipase for hydrolytic reactions. Additionally, the lower KM and higher Vmax values of the immobilized enzyme for hydrolysis of 4-nitrophenyl palmitate indicated an increased efficiency of the immobilized lipase. The immobilized lipase exhibited higher esterification efficiency compared with free lipase for synthesis of ethyl isovalerate. It also exhibited fairly good reusability, with about 8.5% reduction in esterification efficiency for ethyl isovalerate synthesis over ten cycles of reuse.
- Dandavate, Vrushali,Keharia, Haresh,Madamwar, Datta
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experimental part
p. 37 - 45
(2012/04/10)
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- Combinatorial synthesis of 3,5-Dimethylene substituted 1,2,4-Triazoles
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Combinatorial cyclizations of imidates and hydrazides with methylene linked R groups, generated from the corresponding nitriles and carboxylic acids, respectively, provided a large library of 3,5-dimethylene substituted 1,2,4- trizoles. 2011 Bentham Science Publishers Ltd.
- Woodard, Scott S.,Jerome, Kevin D.
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experimental part
p. 132 - 137
(2012/04/18)
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- Synthesis of aryl-substituted bis(imino) pyridine iron dinitrogen complexes
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The synthesis and characterization of dimeric, aryl-substituted bis(imino)pyridine iron dinitrogen complexes is described. In contrast to reduction with sodium amalgam where bis(chelate) iron compounds were isolated, stirring (ArPDI)FeBr2 or (MeBPDI)FeBr 2 (PDI = 2,6-(ArN=CMe)2C5H3N; Ar = 2,6-Et2-C6H3N (EtPDI), 2,6-Me 2-C6H3N (MePDI), 2- iPr,6-Me-C6H3N (Me,iPrPDI); MeBPDI = 2,6-(2,6-Me2-C6H3N=CPh) 2C5H3N) with sodium naphthalenide resulted in isolation of the desired iron dinitrogen compounds as diamagnetic solids. Two examples, [(EtPDI)Fe(N2)]2(μ2- N2) and [(MeBPDI)Fe(N2)] 2(μ2-N2), were characterized by X-ray diffraction. The solid state metrical parameters, in combination with infrared and Moessbauer spectroscopic data, establish ferrous compounds with doubly reduced chelates. Each new bis(imino)pyridine iron dinitrogen compound was screened for the catalytic hydrogenation of ethyl-3-methylbut-2-enoate, and the compound bearing the smallest aryl substituent, [(MePDI)Fe(N 2)]2(μ2-N2), offers significant improvement over the original (iPrPDI)Fe(N2)2 pre-catalyst and is one of the most active iron pre-catalysts known.
- Russell, Sarah K.,Darmon, Jonathan M.,Lobkovsky, Emil,Chirik, Paul J.
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experimental part
p. 2782 - 2792
(2010/05/15)
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- INFANT FORMULA CONTAINING AN AROMA COMPOSITION FOR USE AS FRAGRANCE
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The invention relates to a nutraceutical composition such as infant formula or infant food comprising a) a defined aroma composition; b) a methodology for developing, maintaining certain aroma constituents in the infant formula and an aroma or fragrance composition to be used to increase the acceptance of a person or an object by the baby or new born.
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- Hydroalkoxycarbonylation of olefins in the presence of palladium phosphine complexes: High activity and regioselectivity
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Several types of catalyst systems were examined in the olefin hydroalkoxycarbonylation reaction. The systems contained Pd(PPh 3)4, PdCl2(PPh3)2, or some other palladium compounds as a principal component. The second component (promoter) was p-toluenesulfonic acid or diphenyl(m-sulfophenyl)phosphine, which combines both the ligand and promoter functions. An important feature of these systems is their high activity in the hydroalkoxycarbonylation of ethylene and a high regioselectivity (83-100%) in the hydroalkoxycarbonylation of α-olefins with respect to linear products. Thus, it was unnecessary to introduce additional stabilizing ligands to augment the catalyst and promoter. The esters obtained can find application in the pharmaceutical industry and perfumery, as well as in other industries. Nauka/Interperiodica 2006.
- Chepaikin,Bezruchenko,Suerbaev,Shalmagambetov
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p. 117 - 121
(2007/10/03)
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- Kinetic study on lipase-catalyzed esterification in organic solvents
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A twin inhibition is observed tor the esterification reaction between ethanol and isovaleric acid using immobilized lipase from Rhizomucor miehei in hexane and in mixed solvent system. The observed bi-substrate inhibition pattern follows a Ping-Pong Bi-Bi mechanism with dead-end inhibition of enzyme by both the substrates. An increase in Km value for alcohol in mixed solvent (0.645 M) than in hcxane (0.256 M), indicates that the enhanced solvation of ethanol in mixed solvent results in lower degree of inhibition.
- Chowdary,Prapulla
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p. 2322 - 2327
(2007/10/03)
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- Acylation and alkoxycarbonylation of benzoxazoline-2-thione and benzothiazoline-2-thione
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Acylation of benzoxazoline-2-thione (1) and benzothiazoline-2-thione (2) with acetic anhydride (3) and acyl chlorides (4) gave N-acyl (5, 6) and/or S-acyl (7, 8) derivatives depending on the nature of acylating agents and bases used. Alkoxycarbonylation of 1 with aralkyl chlorocarbonates (9) gave N-alkoxycarbonyl derivatives (10) mainly, while that of 2 with aralkyl chloroccarbonates (9) gave S-alkoxycarbonyl derivatives (12) exclusively. Photolysis of N-acyl derivatives (5 or 6) in the presence of alcohols afforded 1 or 2, respectively, together with esters (16).
- Nishio, Takehiko,Shiwa, Kiyoko
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p. 313 - 324
(2007/10/03)
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- Structure-function correlation in lipase catalysed esterification reactions of short and medium carbon chain length alcohols and acids
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An attempt has been made to correlate the carbon chain lengths of acids and alcohols to the extent of esterification in the Rhizomucor miehei lipase catalyzed esterification reactions involving acids of carbon chain length C2-C5 and alcohols of carbon chain length C1-C8.
- Divakar, Soundar
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p. 1919 - 1922
(2007/10/03)
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- Syntheses based on monocarbon molecules: III.1 hydroethoxycarbonylation of 2-methylpropene in the presence of palladium phosphine complexes at a low pressure of carbon monoxide
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Among the catalytic systems PdCl2(PPh3)2, PdCl2(PPh3)2-PPh3, PdCl2(PPh3)2-TsOH, PdCl2(PPh3)2-PPh3-TsOH, and PdCl2-PPh3-TsOH, the latter is the best catalyst for hydroethoxycarbonylation of 2-methylpentene at a low pressure of carbon monoxide.
- Suerbaev,Shalmagambetov,Zhubanov
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p. 1924 - 1926
(2007/10/03)
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- Syntheses based on monocarbon molecules: II. Synthesis of ethyl isovalerate by isobutene carbonylation with carbon monoxide and ethanol in the presence of phosphine palladium complexes. Ethyl α-bromoisovalerate
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Optimal conditions for the synthesis of ethyl isovalerate by isobutene hydrocarbalkoxylation with carbon monoxide and ethanol in the presence of the catalytic system PdCl2(PPh3)2 + PPh3 + p-TsOH were found. Bromination of ethyl isovalerate under conditions of the Hell-Volgard-Zelinskii reaction gave ethyl α-bromoisovalerate which is the main active component in korvalol medicine.
- Suerbaev,Abyzbekova,Shalmagambetov,Zhubanov
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p. 516 - 517
(2007/10/03)
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- Ruthenium clay catalyzed chemoselective hydrogenation of unsaturated esters, epoxides, sulfones and phosphonates
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Ru-clays were prepared using montmorillonite-PPh2 or montmorillonite-bpy and RuCl3·H2O. The clays obtained were found to be effective catalysts for the reduction of unsaturated esters, epoxides, sulfones and phosphonates.
- Aldea, Raluca,Alper, Howard
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p. 349 - 354
(2007/10/03)
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- Separation of methylene chloride from tetrahydrofuran by extractive distillation
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Methylene chloride is difficult to separate from tetrahydrofuran by conventional distillation or rectification because of the proximity of their vapor pressures. Methylene chloride can be readily separated from tetrahydrofuran by extractive distillation. Effective agents are 1-pentanol, 1,2-butanediol and 3-nitrotoluene.
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- Hydrogenation Catalysis by an Iron Porphyrin and Its Application to α,β-Unsaturated Esters
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Chloro(5,10,15,20-tetraphenylporphyrinato)iron(III) in tetrahydrofuran-methanol catalysed the hydrogenation of α,β-unsaturated esters by NaBH4 to the saturated esters; turnovers of up to 4580 h-1 have been attained for the hydrogenation of ethyl 2-methylbut-2-enoate.Deuterium labelling studies showed that the H(1-) of NaBH4 and the H(1+) of MeOH add to the β- and α-carbons of the double bond.A slower hydrogenation of oct-1-ene was accompanied by isomerization to oct-2-enes.Spectroscopy (UV/VIS, 1H NMR and ESR) suggests that hydrogenation proceeds via an iron(II) intermediate, and an alkyliron(II) species seems likely.
- Sakaki, Shigeyoshi,Kojima, Tatsuya,Arai, Toru
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- ORGANOMANGANESE(II) REAGENTS XXII. COPPER-CATALYZED CONJUGATE ADDITION OF ORGANOMANGANESE REAGENTS TO α,β-ETHYLENIC ESTERS.
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Copper-catalyzed conjugate addition of organomanganese reagents to α,β-ethylenic esters easily takes place in THF at 0 deg C, in the presence of 3 percent CuCl and Me3SiCl.Good to moderate yields are obtained from organomanganese reagents prepared from organolithium or organomagnesium compounds.
- Cahiez, Gerard,Alami, Mouad
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p. 7423 - 7424
(2007/10/02)
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- Organocopper conjugate addition reaction in the presence of trimethylchlorosilane
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In the presence of TMSCl, the conjugate addition of organocuprates to various α, β-unsaturated esters, amides, ketones and nitriles is greatly improved. The reaction is faster, the yields are very high and the reaction is very clean.
- Alexakis,Berlan,Besace
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p. 1047 - 1050
(2007/10/02)
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- Hydrogenolysis of Small Cycloalkanes, XI. - Hydrogenation of Bicyclobutane-1- and -2-carboxylates
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Hydrogenation of ethyl bicyclobutane-2-carboxylate (1) with Pd/C in ethanol at normal conditions leads to 95 percent of ethyl 2-methylbutyrate (2) and 5 percent of ethyl n-valerate (3).The corresponding 1-carboxylic acid ester 8 yields 99 percent of 2 but less than 1 percent of cyclobutane as well as the cis- and trans-2-methylcyclopropanecarboxylates 5 and 9.In this case 2-methylenebutyric and cis- and trans-2-methylcrotonic acid esters (10, 11a, and 12) can be detected as intermediates.From these, conclusions can be made about the mechanism at the catalyst. 5 is the main product with a poisoned catalyst.
- Hertzsch, Winfried,Musso, Hans
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p. 1485 - 1491
(2007/10/02)
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- Theoretical Modelling of Pyrolysis Reactions. Thermal Retroaldol Reactions of β-Hydroxyesters
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Reaction rate constants for the thermal retroaldol reaction of eight β-hydroxyesters were determined, and these were well correlated with MM2-derived steric energies.
- Houminer, Yoram,Kao, James,Seeman, Jeffrey I.
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p. 1608 - 1609
(2007/10/02)
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- KINETICS AND MECHANISM OF THE ADDITION OF ALCOHOLS TO KETENES IN DIETHYL ETHER SOLUTION IN THE PRESENCE OF BORON TRIFLUORIDE
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The kinetics are reported of the boron trifluoride-catalysed additions of seven alcohols to dimethylketene in diethyl ether solution at 25 deg C.All the reactions involve the rapid initial formation of 1:1 alcohol-boron trifluoride adduct (formation constant K) which transfer a proton to the ketene in the slow step of the addition.For t-butyl alcohol, ethanol, methanol, phenylmethanol, and 2-chloroethanol the K values are > 1000, 320+/-50, 300+/-50, 80+/-20, and 65+/-15 l/mol, respectively.The more acididc an alcohol the faster is the reaction of its 1:1 boron trifluoride adduct with the ketene.For t-butyl alcohol the relatively slow reaction of its adduct is catalysed by a further molecule of the adduct and by free boron trifluoride.At 25 deg C the spontaneous addition of ethanol to diphenylketene in ether (like that to dimethylketene) is first order in the ketene and third order in the ethanol concentration.In this reaction diphenylketene is ca. 10-fold more reactive than the dimethyl derivative in the concentration range studied.Whereas the addition of boron trifluoride to the solution catalyses the addition of ethanol (and the other alcohols) to dimethylketene to such an extent that the spontaneous addition makes a negligible contribution to the overall rate, with diphenylketene the alcohol-boron trifluoride adduct is relatively so unreactive that added boron trifluoride strongly inhibits the spontaneous addition.The ethanol-boron trifluoride adducts is > 10E4-fold less reactive towards diphenylketene.These results support our previous conclusions concerning additions of acidic species to ketenes.
- Poon, Nai L.,Satchell, Derek P. N.
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p. 1083 - 1088
(2007/10/02)
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- FACILE ESTERIFICATION OF CARBOXYLIC ACIDS WITH ORGANOPHOSPHORUS REAGENTS. NOVEL APPLICATION OF ALKYLPHOSPHORIC ESTERS (APE)
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A mixture of alkyl phosphate esters (APE) obtained from P4O10 and alkanols taken in 1:6 mole ratio is an excellent esterification reagent for several classes of carboxylic acids.This new reagent offers several advantages compared to conventional reagents.
- Balasubramaniyan, V.,Bhatia, V. G.,Wagh, S. B.
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p. 1475 - 1485
(2007/10/02)
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- CONJUGATE ADDITION REACTION OF α,β-UNSATURATED ESTERS WITH HIGHER ORDER CUPRATES R2Cu(CN)Li2
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Higher order, mixed cuprates R2Cu(CN)Li2 react rapidly and in high yields with β-substituted enoates. α,β-Disubstituted systems afford moderate yields of product in certain cases whereas β,β-disubstituted unsaturated esters lead to 1,2-followed by 1,4-add
- Lipshutz, Bruce H.
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p. 127 - 130
(2007/10/02)
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- Dialkyl sulphites: Convenient Reagents for Esterification of Carboxylic Acids
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Several mono and dicarbocylic acids undergo esterification with dimethyl/ diethyl sulphite in the presence of traces of sulphuric acid in a one-pot reaction.
- Bhatia, V. G.,Shaik, A. S.,Tongare, D. B.,Balasubramaniyan, V.
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p. 259 - 260
(2007/10/02)
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