- Monitoring of biological one-electron reduction by 19F NMR using hypoxia selective activation of an 19F-labeled indolequinone derivative
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(Chemical Equation Presented) Biological reduction of fluorine-labeled indolequinone derivative (IQ-F) was characterized by 19F NMR for quantitative molecular understanding. The chemical shift change in 19F NMR allowed monitoring of the enzymatic reductio
- Tanabe, Kazuhito,Harada, Hiroshi,Narazaki, Michiko,Tanaka, Kazuo,Inafuku, Kenichi,Komatsu, Hirokazu,Ito, Takeo,Yamada, Hisatsugu,Chujo, Yoshiki,Matsuda, Tetsuya,Hiraoka, Masahiro,Nishimoto, Sei-Ichi
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Read Online
- Immobilized Platinum Hydride Species as Catalysts for Olefin Isomerizations and Enyne Cycloisomerizations
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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.
- Bauer, Matthias,Cronin, Steve P.,Dyballa, Michael,Estes, Deven P.,Li, Zheng,Maier, Sarah,Nowakowski, Michal,Vu Dinh, Manh-Anh
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p. 1751 - 1757
(2021/06/28)
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- A janus-headed lewis superacid: Simple access to, and first application of Me3Si-F-Al(ORF)3
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Upon reaction of gaseous Me3SiF with the in situ prepared Lewis acid Al(ORF)3, the stable ion-like silylium compound Me3Si-F-Al(ORF)3 1 forms. The Janusheaded 1 is a readily available smart Lewis acid that differentiates between hard and soft nucleophiles, but also polymerizes isobutene effectively. Thus, in reactions of 1 with soft nucleophiles (Nu), such as phosphanes, the silylium side interacts in an orbital-controlled manner, with formation of [Me3Si-Nu]+ and the weakly coordinating [F-Al(ORF)3]-or [(FRO)3Al-F-Al(ORF)3]- anions. If exchanged for hard nucleophiles, such as primary alcohols, the aluminum side reacts in a charge-controlled manner, with release of FSiMe3 gas and formation of the adduct R(H)O-Al(ORF)3. Compound 1 very effectively initiates polymerization of 8 to 21 mL of liquid C4H8 in 50 mL of CH2Cl2 already at temperatures between -57 and -30 8C with initiator loads as low as 10 mg in a few seconds with 100 % yield but broad polydispersities.
- Rohde, Michael,Muller, Lutz O.,Himmel, Daniel,Scherer, Harald,Krossing, Ingo
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supporting information
p. 1218 - 1222
(2014/04/03)
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- The Al(ORF)3/H2O/phosphane [RF = C(CF3)3] System - Protonation of phosphanes and absolute bronsted acidity
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The synthesis of the classical, neutral donor-acceptor adducts Ph 2MeP-/Ph3P-/Ph3As-Al(ORF) 3 and H2O-Al(ORF)3 [1, 2, 3, 4, ORF = OC(CF3)3] is reported. The intermediate H2O-Al(ORF)3 (4) was generated by substitution of PhF in PhF-Al(ORF)3 with H2O and was analyzed in a long-term NMR study over 22 days. This Bronsted acidic system was used in orienting experiments to protonate phosphanes such as PMePh2, PPh3, PCy3, P(tBu)3, and PCy2[2,4,6-(iPr)3C6H2]. Depending on the use of one or two equivalents of PhF-Al(ORF)3, the new weakly coordinating anions [(RFO)3Al(μ-OH) Al(ORF)3]- or [HOAl(ORF) 3]- were obtained. However, in dependence of the steric bulk of the phosphanes, stable and unreactive R3P-Al(OR F)3 adducts were also observed in the NMR experiments. The absolute acidity of the key H2O-Al(ORF)3 adduct was evaluated by the relaxed COSMO cluster-continuum (rCCC, COSMO = conductor-like screening model) model in fluorobenzene solution. For a 0.001 M solution of H2O-Al(ORF)3, the medium acidity resulted as -986 kJ mol-1 or a pHabs value of 173. Long-term hydrolysis of H2O-Al(ORF)3 (4), probably to give HORF and HOAl(ORF)2 followed by trimerization, gave [HOAl(ORF)2]3 (10), which was identified by X-ray diffraction. Small donor ligands such as Ph 2MeP, Ph3P, Ph3As, or even H2O form classical donor-acceptor adducts with the Lewis superacid Al(OR F)3 [RF = C(CF3)3]. FLP-like (FLP = frustrated Lewis pair) combinations of this Lewis acid, phosphanes, and water then lead to [HPR3]+ and two new weakly coordinating anions [HOAl(ORF)3]- and [(FRO)3Al(μ-OH)Al(ORF)3] -. The absolute acidity of H2O-Al(ORF) 3 is evaluated.
- Kraft, Anne,Possart, Josephine,Scherer, Harald,Beck, Jennifer,Himmel, Daniel,Krossing, Ingo
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p. 3054 - 3062
(2013/07/27)
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- Hydrogen bonding between solutes in solvents octan-1-ol and water
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The 1:1 equilibrium constants, K, for the association of hydrogen bond bases and hydrogen bond acids have been determined by using octan-1-ol solvent at 298 K for 30 acid-base combinations. The values of K are much smaller than those found for aprotic, rather nonpolar solvents. It is shown that the log K values can satisfactorily be correlated against αH 2?βH2, where αH 2 and βH2 are the 1:1 hydrogen bond acidities and basicities of solutes. The slope of the plot, 2.938, is much smaller than those for log K values in the nonpolar organic solvents previously studied. An analysis of literature data on 1:1 hydrogen bonding in water yields a negative slope for a plot of log K against αH 2?βH2, thus showing how the use of very strong hydrogen bond acids and bases does not lead to larger values of log K for 1:1 hydrogen bonding in water. It is suggested that for simple 1:1 association between monofunctional solutes in water, log K cannot be larger than about -0.1 log units. Descriptors have been obtained for the complex between 2,2,2-trifluoroethanol and propanone, and used to analyze solvent effects on the two reactants, the complex, and the complexation constant.
- Abraham, Michael H.,Gola, Joelle M. R.,Cometto-Muniz, J. Enrique,Acree, William E.
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experimental part
p. 7651 - 7658
(2011/02/25)
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- Convenient syntheses of 1,1,1,3,3,3-hexafluoro-2-organyl-propan-2-ols and the corresponding trimethylsilyl ethers
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A new convenient synthetic procedure to obtain various 1,1,1,3,3,3- hexafluoro-2-organyl-propan-2-ols and the corresponding trimethylsilyl ethers has been worked out starting from anhydrides or activated esters of carboxylic acids and trimethyl(trifluoromethyl)silane in the presence of tetramethylammonium fluoride. Conditions for the selective formation of 1,1,1,3,3,3-hexafluoro-2-organyl-propan-2-ols as well as the trimethylsilyl derivatives have been found.
- Babadzhanova,Kirij,Yagupolskii,Tyrra,Naumann
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p. 1813 - 1819
(2007/10/03)
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- Perfluoroalkyl hypobromites: Synthesis and reactivity with some fluoroalkenes
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The first perfluoroalkyl hypobromites have been prepared by the reaction of bromine(I) fluorosulfate with perfluorinated tertiary alkoxides of general formula RfC(CF3)2ONa where Rf=CF3 or CF3CF2. These hypobromites are of lower thermal stability but they behave similarly to analogous hypochlorites and decompose rapidly above -20 °C to give CF3C(O) CF3 and either CF3Br or CF3CF2Br. New polyfluoroethers generated from the reaction of perfluoroalkyl hypobromites with fluoroalkenes have been characterized by 19F and 1H NMR spectroscopy, IR spectroscopy and MS.
- Anderson, John D.O.,DesMarteau, Darryl D.
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p. 147 - 152
(2007/10/03)
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- Fluorinated Tertiary Alcohols and Alkoxides from Nucleophilic Trifluoromethylation of Carbonyl Compounds
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(CH3)3SiCF3 reacts with fluoro ketones in the presence of excess KF in CH3CN to produce alkoxides derived from formal addition of CF3(1-) to the carbonyl carbon.These alkoxides may be isolated as such or acidified to the corresponding alcohols.Ketones to which this technique was applied include (CF3)2C=O, CF3C(O)CF2Cl, CF3C(O)CF2H, and 2C=O.The last compound reacts with replacement of one of its perfluoroisopropyl groups by CF3.With 2 equiv of TMS-CF3, the acid fluorides RC(O)F (R = CF3CF2, n-C3F7, n-C7F15) yield products of the form RC(CF3)2OX (X = K, H) due to both substitution and addition of CF3 at the carbonyl.Similarly, F2C=O with 3 equiv of TMS-CF3 provides a novel and high-yield synthesis of the perfluoro-tert-butoxide group.Phosgene does not appear to react directly with the TMS-CF3/KF system, but is converted first to CF2C=O.The intermediate ketone CF3CF2C(O)CF3 is observed in reactions of equimolecular amounts of CF3CF2C(O)F and TMS-CF3.
- Kotun, Stefan P.,Anderson, John D. O.,DesMarteau, Darryl D.
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p. 1124 - 1131
(2007/10/02)
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- TRICHLOROMETHYLATION OF FLUOROKETONES
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The nuclophilic trichloromethylation of fluoroketones was carried out by the reductive addition of CCl4 in the presence of aluminum or by the reaction of trichloroacetic acid in HMPTA.The trichloromethylcarbinols obtained were used in the synthesis of perfluorinated tertiary alcohols and trifluoromethylated 1,1-dichlorooxiranes. Keywords: fluoroketones, trichloromethylation, fluorine-containing trichloromethylcarbinols and 1,1-dichlorooxiranes, synthesis.
- Zeifman, Yu. V.
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p. 370 - 373
(2007/10/02)
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- Oxidative displacement and addition reactions of F-tert -butyl hypochlorite with metal chlorides and oxidative additions to several elements
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Transition-metal and post-transition-metal chlorides underwent oxidative displacement and oxidative addition reactions with F-tert-butyl hypochlorite to form new F-tert-butoxides. Thus, when (CF3)3COCl was reacted with VOCl3, TiCl4, and CrO2Cl2, the stable compounds VO[(CF3)3CO]3, Ti[(CF3)3CO]4, and CrO2[(CF3)3CO]2 were formed. With Vaska's compound, oxidative addition occurred at iridium but the phenyl groups of P(C6H5)3 were also involved. UCl4, Cu2Cl2, SnCl4, and SiCl4 did not react under the experimental conditions used. F-tert-Butyl hypochlorite has also been shown to add oxidatively to such elements as sulfur, lead, tellurium, bismuth, and iodine to form S[(CF3)3CO]4, Pb[(CF3)3CO]2, Te[(CF3)3CO]4, Bi[(CF3)3CO]3, and I[(CF3)3CO]3, respectively. With (C2H5)2NH, (CF3)3COH formed a 1:1 adduct.
- Canich, Joann M.,Gard, Gary L.,Shreeve, JeaN'Ne M.
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p. 441 - 444
(2008/10/08)
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- Perfluorotertiaryalkyl ethers
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A monohydroxyalkyl, perfluorotertiaryalkyl ether, said monohydroxylalkyl group having no more than 16 carbon atoms and said perfluorotertiary alkyl group having the structure EQU1 where Rf is a perfluoroalkyl group of less than 10 carbon atoms.
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- Trifluoromethylsulfinyl esters of fluorinated alcohols
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Reactions of trifluoromethylsulfinyl fluoride, CF3SOF, with fluoro alcohols in the presence of NaF(CsF) were used to prepare a series of new sulfinate esters of the general formula RfOS(O)CF3 (Rf = CF3(CH3)CH, CF3(CH3)2C, (CF3)2CH, (CF3)2C(CH3), CF3(CF2Cl)CH). Perfluoro-tert-butyl trifluoromethylsulfinate, (CF3)3COS(O)CF3, was prepared by the reaction of trifluoromethylsulfinyl chloride, CF3SOCl, with the (CF3)3COH·Me3N adduct. The reaction of ClF with (CF3)2CHOS(O)CF3 resulted in the cleavage of the S-CF3 bond to give (CF3)2C(H)OS(O)F. Because of a chiral sulfur center, the methyl groups in CF3(CH3)2COS(O)CF3 and the trifluoromethyl groups in (CF3)2C(H)OS(O)CF3 and (CF3)2C(H)OS(O)F are magnetically nonequivalent. The nmr spectra of CF3(CH3)CHOS(O)CF3 and CF3(CF2Cl)CHOS(O)CF3 showed the presence of two diastereoisomers. With the exception of CF3(CH3)CHOS(O)CF3, all of the trifluoromethylsulfinates are decomposed by CsF in the 25-100° temperature range. Infrared, mass, and nmr spectra and elemental analysis data are reported.
- Majid, Abdul,Shreeve, Jean'ne M.
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p. 2710 - 2714
(2008/10/08)
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