- Phosphine-Catalyzed Vinylation at Low Acetylene Pressure
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The vinylation of various nucleophiles with acetylene at a maximum pressure of 1.5 bar is achieved by organocatalysis with easily accessible phosphines like tri-n-butylphosphine. A detailed mechanistic investigation by quantum-chemical and experimental methods supports a nucleophilic activation of acetylene by the phosphine catalyst. At 140 °C and typically 5 mol % catalyst loading, cyclic amides, oxazolidinones, ureas, unsaturated cyclic amines, and alcohols were successfully vinylated. Furthermore, the in situ generation of a vinyl phosphonium species can also be utilized in Wittig-type functionalization of aldehydes.
- Bienewald, Frank,Comba, Peter,Hashmi, A. Stephen K.,Menche, Maximilian,Rominger, Frank,Schafer, Ansgar,Schaub, Thomas,Sitte, Nikolai A.,Tuzina, Pavel
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p. 13041 - 13055
(2021/09/18)
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- Photosonoelectrochemical analysis of Lawsonia inermis (henna) and artificial dye used in tattoo and dye industry
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Photosonoelectrochemical (PSEC) analysis of Lawsonia inermis, lawsone and ?-Phenylenediamine were investigated in ethanol to understand the degradation mechanism and harmful byproducts. To simulate the operating conditions of the tattoo ink, dye solutions
- Chandrakalavathi,Sudha,Sindhuja,Harinipriya,Jeyalakshmi
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- Decomposition of a Β-O-4 lignin model compound over solid Cs-substituted polyoxometalates in anhydrous ethanol: acidity or redox property dependence?
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Production of aromatics from lignin has attracted much attention. Because of the coexistence of C–O and C–C bonds and their complex combinations in the lignin macromolecular network, a plausible roadmap for developing a lignin catalytic decomposition process could be developed by exploring the transformation mechanisms of various model compounds. Herein, decomposition of a lignin model compound, 2-phenoxyacetophenone (2-PAP), was investigated over several cesium-exchanged polyoxometalate (Cs-POM) catalysts. Decomposition of 2-PAP can follow two different mechanisms: an active hydrogen transfer mechanism or an oxonium cation mechanism. The mechanism for most reactions depends on the competition between the acidity and redox properties of the catalysts. The catalysts of POMs perform the following functions: promoting active hydrogen liberated from ethanol and causing formation of and then temporarily stabilizing oxonium cations from 2-PAP. The use of Cs-PMo, which with strong redox ability, enhances hydrogen liberation and promotes liberated hydrogen transfer to the reaction intermediates. As a consequence, complete conversion of 2-PAP (>99%) with excellent selectivities to the desired products (98.6% for phenol and 91.1% for acetophenone) can be achieved.
- Wu, Xuezhong,Jiao, Wenqian,Li, Bing-Zheng,Li, Yanming,Zhang, Yahong,Wang, Quanrui,Tang, Yi
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p. 1216 - 1228
(2017/07/10)
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- Ruthenium-Catalyzed Olefin Cross-Metathesis with Tetrafluoroethylene and Analogous Fluoroolefins
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This Communication describes a successful olefin cross-metathesis with tetrafluoroethylene and its analogues. A key to the efficient catalytic cycle is interconversion between two thermodynamically stable, generally considered sluggish, Fischer carbenes. This newly demonstrated catalytic transformation enables easy and short-step synthesis of a new class of partially fluorinated olefins bearing plural fluorine atoms, which are particularly important and valuable compounds in organic synthesis and medicinal chemistry as well as the materials and polymer industries.
- Takahira, Yusuke,Morizawa, Yoshitomi
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supporting information
p. 7031 - 7034
(2015/06/25)
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- Iridium Pincer-Catalyzed Dehydrogenation of Ethers Featuring Ethylene as the Hydrogen Acceptor
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We describe efficient methods to dehydrogenate ethers by using iridium pincer complexes (iPr4Anthraphos)-Ir(H)(Cl), 4, iPr4PC(sp3)P-Ir(H)(Cl), 5, and (iPr4PCP)-Ir(H)(Cl), 6. At 120°C, cyclic ethers were dehydrogenated with tert-butylethylene as the hydrogen acceptor with high turnover numbers (over 400 in many cases). Acyclic ethers such as diethyl ether can also be dehydrogenated catalytically with TONs up to 90. The efficient dehydrogenation of cyclic and acyclic ethers using ethylene as a more practical hydrogen acceptor has been demonstrated for the first time. (Figure Presented)
- Lyons, Thomas W.,Bzier, David,Brookhart, Maurice
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p. 4058 - 4062
(2015/09/01)
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- Experimental and theoretical study of the 2-alkoxyethylidene rearrangement
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The rearrangement of 2-ethoxyethylidene, generated photochemically from a nonnitrogenous precursor, leads to ethyl vinyl ether. Although this product could result, in principle, from a 1,2-hydrogen shift and/or a 1,2-ethoxy shift in the carbene, a deuterium labeling study indicates an essentially exclusive preference for hydrogen migration. The experimental results are in agreement with CCSD and W1BD calculations for the simpler 2-methoxyethylidene system that show a prohibitively large barrier for the methoxy shift and a negligible barrier for the hydride shift. 2011 American Chemical Society.
- Graves, Kimberly S.,Thamattoor, Dasan M.,Rablen, Paul R.
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experimental part
p. 1584 - 1591
(2011/05/19)
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- A Simple, effective boron-halide ethoxylation catalyst
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Boron esters B(OR)3, readily derived from boric acid and alcohols, combine with iodide or bromide to catalyze the ethoxylation of alcohols and phenols, giving good rates and narrow product distributions. The combined action of a weak electrophile [B(OR)3] and a weak nucleophile (halide) allows for the ethoxylation of base-sensitive alcohols. Experiment suggests a new mechanism for this commercially important reaction proceeding through key β-haloalkoxy intermediates.
- Moloy, Kenneth G.
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body text
p. 821 - 826
(2010/07/05)
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- METHOD FOR PRODUCING , -UNSATURATED ETHER
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Disclosed is a method for producing an α,β-unsaturated ether efficiently and stably for a long time. In the method for producing an α,β-unsaturated ether, an acetal is thermally decomposed in the presence of a catalyst containing an apatite represented by any of the following formulae (1)-(4). ????????(M)5-y(HZO4)y(ZO4)3-y(X)1-y?????(1) ????????(M)5-y(HPO4)y(PO4)3-y(X)1-y?????(2) ????????(M)5-y+2n(HZO4)y(ZO4)3-y(X)1-y(SiO4)n?????(3) ????????(M)5-y+m(HZO4)y(ZO4)3-y(X)1-y(CO3)m?????(4)
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Page/Page column 9-12; 16-17
(2008/12/04)
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- Process and catalysts for the oxidation of methanol and/or ethanol
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A process for oxidation of methanol, ethanol, or a mixture of methanol and ethanol comprising contacting the methanol and/or ethanol with an oxygen-containing gas and a supported catalyst comprising one or more platinum group oxides. The process conditions and/or catalyst may be selected to as to selectively produce methyl formate from methanol or diethoxyethane from ethanol. The invention also includes certain novel supported platinum group metal oxide catalysts. Preferred catalysts include one or more ruthenium oxides.
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Page/Page column 8
(2008/06/13)
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- New fluoromonomers and methods of production, and new fluoropolymers produced therefrom
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The present invention provides new fluoromonomers having the generic structure: CF2═CF(OCH2CH2)nOR where n is an integer and R is a functional group and methods for producing same. A new method of synthesizing the fluoromonomers is provided. The present invention also relates to new fluoropolymers prepared from any one or combination of the new fluoromonomers and having the generic structure: —[—CF2CF{(OCH2CH2)nOR}—]m— where n is an integer, m is an integer and R represents an unsubstituted or inertly substituted hydrocarbyl group. The method also relates to new copolymers or terpolymers prepared from the new fluoromonomers alone, the new fluoromonomers and existing fluoromonomers or the new fluoromonomers and existing hydrocarbon or functionalized hydrocarbon monomers.
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- Synthesis, characterisation and reactivity of 2-functionalised vinylstannanes
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The functionalised vinylstannanes of the type (E)/(Z)-Ph3SnCR′=CHYRn and (E)/(Z)-Ph3SnC(YRn)=CHR′ (YRn=NMe2, OEt, SMe, SEt; R′=Ph, Bu (n-butyl), Pe (n-pentyl), H) were prepared by non-catal
- Lébl,Hole?ek,Dymák,Steinborn
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- Process for production of unsaturated ether and catalyst used for production of unsaturated ether
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The present invention provides a process for producing an unsaturated ether, which comprises subjecting a glycol ether to intramolecular dehydration in a gas phase in the presence of a catalyst to convert the glycol ether into an unsaturated ether directly in a one-step reaction. As the catalyst, an oxide containing, for example, silicon and an alkali metal is used. The process, which uses no auxiliary raw material, can produce an unsaturated ether (a vinyl ether and/or an allyl ether) simply and safely without generating any waste material derived from the auxiliary raw material.
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- Synthesis of Fischer carbene complex of iridium by C-H bond activation of methyl and cyclic ethers: Evidence for reversible α-hydrogen migration
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We report here a mild and versatile route to Fischer carbene complexes of iridium via the activation of C-H bonds of methyl and cyclic ethers, along with our preliminary studies of this rare family of carbene complexes. Theoretical studies suggest that α-hydrogen migrations can be kinetically favorable if a coordinatively unsaturated species can be accessed. Thus, the lability of the triflate ligand presumably facilitates this process. Further evidence for the rapidity, as well as reversibility, of this rearrangement was obtained by NMR analysis.
- Luecke,Arndtsen,Burger,Bergman
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p. 2517 - 2518
(2008/10/08)
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- Generation and Trapping of α,α'-Dioxosulfines from 1,4-Oxathiine-S-Oxides
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The 1,4-oxathiine-S-oxides 6 when heated at 60 deg C in CHCl3 undergo a retro Diels-Alder reaction with generation of α,α'-dioxosulfine 8.This reactive intermediate can be trapped by electron rich dienophiles as well as by dienes.In both cases the cycloaddition reactions show interesting stereoselective features.
- Capozzi, Giuseppe,Fratini, Paola,Menichetti, Stefano,Nativi, Cristina
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p. 5089 - 5092
(2007/10/02)
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- Isomerization and Decomposition of 2,3-Dimethyloxirane. Studies with a Single-Pulse Shock Tube
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The isomerizations and decompositions of cis- and trans-2,3-dimethyloxirane were studied behind reflected shocks in a pressurized driver single-pulse shock tube over the temperature range 900-1150 K and overall densities of ca. 3*1E-5 mol/cm3.In addition to a cis trans structural isomerization, four isomerization products, methyl ethyl ketone, isobutyraldehyde, ethyl vinyl ether, and 2-butene-3-ol, were obtained under shock heating.A large number of decomposition products were also obtained.The major ones in decreasing order of abundance were CO, C2H4, C2H6, and CH4.In a similar manner to the decomposition of oxirane and methyloxirane, the free-radical reactions in the present system are initiated by a direct decomposition of a thermally excited methyl ethyl ketone which is produced in the course of the isomerization.A reaction scheme composed of 41 species and 65 elementary reactions accounts for the product distribution over the entire temperature range of this investigation provided decomposition channels of thermally excited isomers are included in the scheme.The rate constants obtained for the isomerization reactions are in good agreement with the values extrapolated from low temperatures.First-order Arrhenius rate parameters for the formation of the various reaction products are given and a sensitivity analysis for their production is summarized.
- Lifshitz, Assa,Tamburu, Carmen
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p. 10251 - 10260
(2007/10/02)
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- Selective Hydrogenations of Dienes and Olefins by t)6(py)2>
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Hydrocarbon solutions of t)6(py)2> in the presence of H2 (3 atm, 23 deg C) hydrogenate linear 1,3-dienes to 3-enes, 1,3- and 1,5-cyclooctadiene to cyclooctene, 1,3-cyclohexadiene to cyclohexene, cyclopentene to cyclopentane, and norbornene to norbornane, but do not hydrogenate α- and internal olefins to alkanes, or internal conjugated or unconjugated dienes.
- Barry, Jane T.,Chisholm, Malcolm H.
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p. 1599 - 1600
(2007/10/02)
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- Nucleophilic Addition to Acetylenes in Superbasic Catalytic Systems. VII. Vinylation of Lower Alcohols
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Superbasic systems KOH-DMSO and KOH-HMPA with acetylene and alcohols form highly active catalytic complexes capable of sharply increasing the rate and selectivity of nucleophilic addition of alcohols to acetylene and allowing preparation of high-purity lower alkyl vinyl ethers in high yield under acetylene pressure equal to atmospheric.
- Trofimov, B. A.,Oparina, L. A.,Lavrov, V. I.,Parshina, L. N.
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p. 597 - 600
(2007/10/03)
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- Microwave spectrum, structure, and dipole moment of the trans-cis isomer of ethyl vinyl ether
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Microwave spectra of the trans-cis isomer of ethyl vinyl ether and its nine deuterated species were measured. A plausible molecular structure was obtained from the observed moments of inertia by an application of a diagnostic least-squares technique. The dipole moment and its direction were determined by the Stark effect measurements of several low J transitions for the normal and two deuterated species.
- Hayashi,Inada
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p. 195 - 204
(2007/10/02)
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- Ligands and cationic complexes thereof with technetium-99m
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This invention concerns novel bidentate ligands L having two phosphorus or arsenic atoms. Cationic complexes of the ligands with Technetium-99m, e.g. having the formula [TcO2 L2 ]+, are useful for body imaging, particularly myocardial imaging. The ligands have the general formula where Q is phosphorus or Z is a --CC-- or --CCC-- or --COC-- groups, the four groups Y are all C1-C8 saturated hydrocarbon or fluorohydrocarbon with 1-3 ether oxygen atoms.
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- DIASTEREOSELECTIVE ALDOLIZATION TO TETROSES AND PYRANOSES MEDIATED BY RHODIUM
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Rhodium ions bind to oxygen and unsaturated sites in ethane-1,2-diol derivatives to orient and catalyse these molecules for participation in diastereogenic carbon-carbon, carbon-oxygen, and carbon-hydrogen bond formation.
- Deem, M. L.,Romac, E. A.
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p. 4649 - 4652
(2007/10/02)
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- Infrared Photochemistry of Oxetanes: Mechanism of Chemiluminescence
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The infrared multiphoton (IRMP) induced photolysis of several oxetanes is examined at low pressures (ca. 100 mtorr) while experimental variables such as laser frequency, laser energy, bath gas, and bath gas pressure are altered.The products of the IRMP induced photolysis of 2-acyl-3 ethoxy-2-methyloxetane, Ox1, are primarily biacetyl and ethyl vinyl ether.When the photolysis is run with the collimated beam of a CO2 laser (1-3 J/cm2) luminescence is observed.The intensity of the luminescence varies with the efficiency of the unimolecular decomposition of the oxetane.On the basis of the spectral distribution and temporal behavior of the luminescence following irradiation of Ox1, the emitter is believed to be vibrationally hot electronically excited biacetyl.Similar experiments with 2,2-dimethyl-3-ethoxyoxetane give a weaker emission apparently due to excited-state acetone.Results are discussed in terms of the reverse of the Paterno-Buchi reaction - a diabatic retrophotocycloaddition.
- Farneth, William E.,Johnson, Douglas G.
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p. 773 - 780
(2007/10/02)
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- THIONE PHOTOCHEMISTRY. DUAL PATHWAYS IN ARALKYL THIONE CYCLIZATIONS
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It is shown that aralkyl thiones, which posses an oxygen atom at the δ position in the side chain, can therefore not undergo the preferred δ insertion, and insert at the γ and ε positions.Although ε insertion occurs only from the 1(Π,Π*) state, γ abstraction ( followed by cyclization or cleavage ) occurs from both 1(Π,Π*) and 3(n,Π*) states.The quantum yields of photocyclization of 2c, 2d, and 2g change little with solvent polarity, which suggest that a thione-ether charge transfer interaction contributes little to the cyclization.Fluorescence and product quenching studies are reported which support this.
- Basu, S.,Couture, Axel,Ho, Kam W.,Hoshino, Mikio,Mayo, Paul De,Suau, R.
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p. 246 - 254
(2007/10/02)
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- Pd(II)-CATALYZED 1,3-ALKYL MIGRATION OF 1-ALKENYL ETHYL ACETALS. PREPARATION OF α-ALKYLATED (E)-α,β-UNSATURATED CARBONYL COMPOUNDS.
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Palladium(II) complexes, such as (CH3CN)2PdCl2 and (diene)PdCl2, catalyze 1,3-alkyl migration of 1-alkenyl ethyl acetals and subsequent elimination of ethanol to give α-alkylated (E)-α,β-unsaturated carbonyl compounds in excellent yields.
- Takahashi, Mitsuru,Ishii, Norio,Suzuki, Hiroharu,Moro-Oka, Yoshihiko,Ikawa, Tsuneo
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p. 1361 - 1362
(2007/10/02)
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- Method of producing α,β-unsaturated ether
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A method of producing α,β-ethylenically unsaturated ethers, which comprises decomposing an acetal having at least one hydrogen atom bonded to a carbon atom contiguous to the carbon atom of the group STR1 in its molecule in the presence of a calcium phosphate catalyst to produce a reaction product containing the corresponding α,β-ethylenically unsaturated ether.
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