- Novel ethyl-derivatization approach for the determination of fluoride by headspace gas chromatography/mass spectrometry
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We report a novel derivatization chemistry for determination of fluoride based on the batch reaction of fluoride ions with triethyloxonium tetrachloroferrate(III) in a closed vessel to yield fluoroethane. Gaseous fluoroethane was readily separated from the matrix, sampled from the headspace, and determined by gas chromatography/mass spectrometry. The method was validated using rainwater certified reference material (IRMM CA408) and subsequently applied to the determination of fluoride in various matrixes, including tap water, seawater, and urine. An instrumental limit of detection of 3.2 μg/L with a linear range up to 50 mg/L was achieved. The proposed derivatization is a one-step reaction, requires no organic solvents, and is safe, as the derivatizing agent is nonvolatile. Determination of fluoride is affected by common fluoride-complexing agents, such as Al(III) and Fe(III). The effect of large amounts of these interferences was studied, and the adverse effect of these ions was eliminated by use of the method of standard additions.
- Pagliano, Enea,Meija, Juris,Ding, Jianfu,Sturgeon, Ralph E.,D'ulivo, Alessandro,Mester, Zoltán
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- VIBRATIONAL LEVEL POPULATIONS OF HYDROGEN FLUORIDE PRODUCED IN INFRARED MULTIPLE-PHOTON DECOMPOSITION OF C2H5F.
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CO//2 TEA laser-induced photolysis of C//2H//5F was studied by using a time-resolved infrared fluorescence technique. Molecular elimination of vibrationally excited hydrogen fluoride (HF*) from C//2H//5F*** occurs in the process. Rotational temperatures and vibrational level populations of HF* are estimated from observed fluorescence spectra by computational fitting. Higher vibrational level are populated to a less extent in the decomposition under a collisionless condition. When the pressure of C//2H//5F is increased, however, population inversion is allowed among some levels. Possible reaction mechanism is discussed for the production of HF* at extraordinarily high vibrational levels.
- Ishikawa,Arai
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- Hexafluoro-3-oxatricyclo2,4>hept-6-ene (Hexafluoro-Dewar-benzene Oxide) from the Photochemical Oxidation of Hexafluorobenzene
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Photochemical oxidation of hexafluorobenzene in the vapour phase yields the title compound, which undergoes thermal rearrangement into hexafluorocyclohexa-2,4-dienone and two acid fluorides, attack by diethyl ether at the oxiran ring, and cycloaddition to its C=C double bond.
- Barlow, Michael G.,Haszeldine, Robert N.,Peck, Colin J.
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- Reactions of oxalyl fluoride with electrophiles
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The reactions of oxalyl fluoride with electrophiles in the presence of alkali metal fluoride were carried out. In the reaction with CF3CH2OH (Tl = CF3SO2) or CH3CH2OTf, the synthesis of di-
- Murata, Junji,Tamura, Masanori,Sekiya, Akira
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- Activation of SF6 at Platinum Complexes: Formation of SF3 Derivatives and Their Application in Deoxyfluorination Reactions
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The activation of SF6 at [Pt(PR3)2] R=Cy, iPr complexes in the presence of PR3 led selectively and in an unprecedented reaction route to the generation of the SF3 complexes trans-[Pt(F)(SF3)(PR3)2]. These can also be synthesized from SF4 and the SF2 derivative trans-[Pt(F)(SF2)(PCy3)2][BF4] was characterized by X-ray crystallography. trans-[Pt(F)(SF3)(PR3)2] complexes are useful tools for deoxyfluorination reactions and novel fluorido complexes bearing a SOF ligand are formed. Based on these studies a process for the deoxyfluorination of ketones was developed with SF6 as fluorinating agent.
- Berg, Claudia,Braun, Thomas,Ahrens, Mike,Wittwer, Philipp,Herrmann, Roy
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supporting information
p. 4300 - 4304
(2017/04/04)
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- Steric crowding makes challenging Csp3 - F reductive eliminations feasible
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A high-yielding fluorination of (triphos)Pt-R+ has been achieved using an array of F+ sources, with XeF2 yielding R-F in minutes. The C-F coupling proved to be a stereoretentive process that proceeds via a concerted reductive elimination from a putative dicationic Pt(IV) center. The larger the steric congestion of the (triphos)Pt-Csp3+ complexes, the more efficient the fluorination, seemingly a result of sterically accelerated C-F reductive elimination along with simultaneous deceleration of its competing processes (β-H elimination).
- Zhao, Shu-Bin,Becker, Jennifer J.,Gagne, Michel R.
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scheme or table
p. 3926 - 3929
(2011/10/03)
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- OXONIUM AND SULFONIUM SALTS
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The present invention relates to oxonium salts having [(Ro)3O]+ cations and sulfonium salts having [(Ro)3S]+ cations, where Ro denotes straight-chain or branched alkyl groups having 1-8 C atoms or phenyl which is unsubstituted or substituted by Ro, ORo, N(Ro)2, CN or halogen, and anions selected from the group of [PFx(CyF2y+1?zHz)6?x]? anions, where 2≦x≦5, 1≦y≦8 and 0≦z≦2y+1, or anions selected from the group of [BFn(CN)4?n]? anions, where n=0, 1 , 2 or 3, or anions selected from the group of [(Rf1SO2)2N]? anions or anions selected from the group of [BFwRf24?w]? anions, to processes for the preparation thereof, and to the use thereof, in particular for the preparation of ionic liquids.
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Page/Page column 12
(2009/03/07)
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- Catalyst and process for contacting a hydrocarbon and ethylene
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A process of contacting at least one feed hydrocarbon, containing three to about seven carbon atoms per molecule, and ethylene in a hydrocarbon-containing fluid in the presence of a catalyst composition to provide at least one product hydrocarbon isomer containing about four to about nine carbon atoms per molecule is provided. The at least one feed hydrocarbon can be selected from paraffins, isoparaffins, and the like and combinations thereof. The catalyst composition contains a hydrogen halide component, a sulfone component, and a metal halide component.
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- PREPARATION OF SELECTED FLUOROOLEFINS
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A process is disclosed for producing (CF3)2C=CH2, CF3CH=CF2, CF2=C(CF3)OCF2CHF2 and C6H5C(CF3)=CF2. The process involves contacting the corresponding fluorocarbon starting material selected from (CF3)2CFCH2F, (CF3)2CHF, (CF3)2CFOCF2CHF2 and C6H5CF(CF3)2, in the vapor phase, with a defluorination reagent selected from carbon, copper, iron, nickel and zinc at an elevated temperature of at least 300 DEG C.
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- New synthetic method of alkyl perfluoroalkyl ethers
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vic-Difluorination of alkyl perfluoroenol ethers proceeded with high- valence metal fluoride, such as cobalt (III) fluoride and potassium tetrafluorocobaltate, in good yields to afford alkyl perfluoroalkyl ethers.
- Tamura, Masanori,Takubo, Seij,Quan, Heng-Dao,Sekiya, Akira
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p. 343 - 344
(2007/10/03)
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- Oxidative fluorination of S, Se and Te compounds
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The synthesis and mechanism of formation of cis- and trans-Ph2SF4 is described. Starting compounds are Ph2S or Ph2SF2 and the oxidizing agent is XeF2 in the presence of Et4NCl. Also described is the synthesis of related chalcogen(IV and VI) fluorides such as t-butylSF3, difluorodibenzothiophene, PhSeF3, Ph2SeF2, PhSF5, p-MeC6H4SF5, PhSeF5, and PhTeF5. The reactions of Ph2S(O)F2 with alcohols and with the H2O-HF-glass system are briefly described.
- Ou, Xiaobo,Janzen, Alexander F.
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p. 279 - 283
(2007/10/03)
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- Kinetics and mechanism of the reactions of 2,3-butadione with F and Cl atoms, UV absorption spectra of CH3C(O)C(O)CH2· and CH3C(O)C(O)CH2O2· radicals, and atmospheric fate of CH3C(O)C(O)CH2O· radicals
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FTIR-smog chamber techniques were used to determine rate constants for the gas-phase reaction of Cl and F atoms with CH3C(O)C(O)CH3 and F atoms with CH3C(O)F of (4.0 ± 0.5) x 10-3, (4.9 ± 0.7) x 10-11, and (3.6 ± 0.4) x 10-12 cm3 molecule-1 s-1, respectively. Two pathways for the reaction of Cl and F atoms with CH3C(O)C(O)CH3 were found: (1a) Cl + CH3C(O)C(O)CH3 → HCl + CH3C(O)C(O)CH2·, (1b) Cl + CH3C(O)C(O)CH3 → CH3C(O)Cl + CH3C(O)·, (2a) F + CH3C(O)C(O)CH3 → HF + CH3C(O)C(O)CH2·, (2b) F + CH3C(O)C(O)CH3 → CH3C(O)F + CH3C(O)·, with branching ratios of k1b/(k1b + k1a) = 0.23 ± 0.02 and k2b/(k2b + k2a) = 0.56 ± 0.09. It was determined that the atmospheric fate of CH3C(O)C(O)CH2O· radicals is decomposition to give HCHO, CO, and CH3C(O)· radicals. Pulse radiolysis coupled to UV absorption spectroscopy was used to study the kinetics of the reaction of F atoms with CH3C(O)C(O)CH3 as well as spectra of CH3C(O)C(O)CH2· and CH3C(O)C(O)CH2O2· radicals over the wavelength range 220-400 nm at 295 K. The rate constant for the reaction of F atoms with CH3C(O)C(O)CH3 was determined to be (4.6 ± 0.8) x 10-11 cm3 molecule-1 s-1. The absorption cross sections of CH3C(O)C(O)CH2 and CH3C-(O)C(O)CH2O2· radicals were (5.4 ± 1.0) x 10-18 at 250 nm and (2.0 ± 0.5) x 10-18 cm2 molecule-1 at 320 nm, respectively. Results are discussed with respect to the available database concerning the reaction of Cl and F atoms with organic compounds.
- Christensen,Sehested,Nielsen,Wallington,Guschin,Hurley
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p. 8913 - 8923
(2007/10/03)
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- Comparative studies in the 19F and 1H NMR chemical shifts in 2,2-difluorohalogenated propanes
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Fluorine-19 chemical shifts were compared with 1H chemical shifts in CF3-CF2-R versus CH3-CF2-R, CF2Cl-CF2-R versus CH2Cl-CF2-R and CFCl2-CF2-R versus CHCl2-CF2-R, where R is a substituted methyl group containing all combinations of H, Cl and F. A good linear relationship was found between the 19F and 1H NMR chemical shifts. Conformational analysis using MNDO calculations was applied to the CF3-CF2-R and CH3-CF2-R series to clarify the interaction between the terminal substituents. In halogenated propanes, 19F and 1H chemical shifts are mainly affected by the through-space interaction between the terminal substituents rather than the electro-negativity.
- Tanuma,Ohnishi,Okamoto,Morikawa
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- Valence-bond isomer chemistry. Part 13. Photochemical oxidation of hexafluorobenzene: formation of hexafluoro-3-oxatricyclo2,4>hept-6-ene and its reactions
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Vapour-phase ultraviolet irradiation of hexafluorobenzene in the presence of oxygen slowly yields hexafluoro-3-oxatricyclo2,4>hept-6-ene (2) (10percent).The CF=CF bond in 2 adds (yields of adducts given) the dienes; cyclopentadiene (74percent), furan (61percent) and 2,5-diphenylisobenzofuran (59percent); benzonitrile oxide (58percent); chlorine (59percent) and bromine (71percent) photochemically.Heptene 2 isomerises thermally hexafluorocyclohexa-2,4-dienone (6) (60percent) at 50 deg C, and reacts with diethyl ether at room temperature yielding ethyl fluoride (89percent) and 2-ethoxypentafluorocyclohexa-2,5-dienone (21percent).The benzonitrile oxide adduct, upon flow pyrolysis at 440 deg C, yields an isomeric oxepin derivative and the cyclohexadienone 6 with longer contact times.The chlorine adduct similarly yields a dichloro-oxepin derivative; attempts to dechlorinate this to hexafluoro-oxepin were unsuccessful.Benzonitrile oxide adds to one or both of the C=C bonds of hexafluorobicyclohexa-2,5-diene; the 1:1 adduct isomerises thermally to the benzonitrile oxide-hexafluorobenzene adduct.
- Barlow, Michael G.,Peck, Colin J.
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p. 179 - 192
(2007/10/02)
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- REACTION OF PERFLUOROISOBUTYLENE AND PERFLUOROPROPYLENE WITH N-TRIMETHYLSILYLPHOSPHAZENES
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Perfluoroisobutylene and perfluoropropylene react with N-trimethylsilylphosphazenes to give perfluoroalkenylphosphazenes R3P=N-CF=CX-CF3 (R=AlkO, NR2, X=F, CF3).The corresponding dialkyl fluorophosphates (AlkO)2P(O)F, were obtained upon the pyrolysis of the alkoxyphosphazenes.
- Lermontov, S. A.,Velikokhat'ko, T. N.,Martynov, I. V.
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p. 2582 - 2584
(2007/10/02)
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- REACTION OF ALKYL 2-CHLORO-1,1,2-TRIFLUOROETHYL ETHERS WITH LEWIS ACIDS
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Ethyl 2-chloro-1,1,2-trifluoroethyl ether heated with boron trifluoride etherate gave ethyl fluoride and chlorofluoroacetyl fluoride.When heated with aluminium chloride, it afforded a mixture of ethyl fluoride, ethyl chloride, chlorofluoroacetyl fluoride, and chlorofluoroacetyl chloride.Treatment of the acyl halides with ethanol yielded ethyl chlorofluoroacetate.Butyl and octyl 2-chloro-1,1,2-trifluoroethyl ethers gave directly butyl and octyl chlorofluoroacetates, respectively, under similar conditions.
- Hudlicky, Milos
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p. 349 - 354
(2007/10/02)
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- Fragmentation Reactions of Some Aliphatic Esters in the NCI(F-) and NCI(NH2-) Mass Spectra
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The NCI(F-) and NCI(NH2-) mass spectra of a series of aliphatic acetates and of methyl and ethyl trimethylacetate have been obtained.The formation of fluoroenolate ions CH2COF- and of carboxamide anions RCONH- (R=CH3, (CH3)3C), respectively, is observed besides formation of - ions and carboxylate ions RCOO- (R=CH3, (CH3)3C).The relative intensities of the different anions depend on the structure of the ester molecules and on the primary reactant anions.Usually, the NCI(NH2-) spectra of the acetates are dominated by - ions (- ions in the case of trideuterioacetates) fragmenting unimolecularly by elimination of an alcohol.The carboxylate ions are important fragments, too, but carboxamide ions are only observed with large intensities in the NCI(NH2-) spectra of the trimethylacetates.The NCI(F-) spectra show much larger intensities of carboxylate ions and fluoroenolate ions.The mechanisms of the fragmentation reactions are discussed.The results indicate that most or even all of the fragment ions in the NCI(F-) mass spectra of aliphatic esters are formed by addition-elimination reactions via a tetrahedral intermediate, while competition between direct proton abstraction and addition-elimination reactions occurs in the NCI(NH2-) mass spectra because of the higher basicity of NH2- resulting in an early transition state for direct proton abstraction.
- Gruetzmacher, Hans-Fr.,Grotemeyer, Barbara
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p. 135 - 142
(2007/10/02)
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- Catalytic Conversion of Fluoroalkyl Alkyl Ethers to Carbonyl Compounds
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Fluoroalkyl alkyl ethers are generally available by attack of alkoxide ion on fluoro olefins.In the presence of Lewis acid catalysts, such methyl and ethyl ethers have now been found to lose methyl or ethyl fluoride, respectively, to give fluorinated carbonyl compounds.The carbonyl compounds include acid fluoride, ketone, keto ester, vinyl ketone, acyl ketene, ketene, and acryloyl fluoride.
- England, David C.
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p. 4007 - 4008
(2007/10/02)
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- Alkylating Properties of Fluorine-Containing Vinylic Ethers
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Some fluorine-containing vinylic ethers show alkylating properties not only to organic (triethylamine), but also to inorganic nucleophylic agents (CsF, KI) in polar aprotic solvents (diglyme, acetonitrile) yielding the corresponding enolates.
- Snegirev, V. F.,Makarov, K. N.,Knunyants, I. L.
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p. 441 - 446
(2007/10/02)
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- Vibrational Energy Transfer Probabilities of Highly Vibrationally Excited Fluoroethane and 1,2-Difluoroethane Molecules
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The collisional loss of vibrational energy from chemically activated CH3CH2F and CH2FCH2F formed with average energies of 91 and 92.5 kcal mol-1, respectively, has been studied at 300 K with four bath gases, SF6, CO2, N2, and He.These chemically activated molecules were formed by combination of CH3 with CH2F and of CH2F with CH2F.The data cover an extensive range of pressure and permit the assignment of the mean energy transfer per collision and the form of the transition probability distribution.For He the (ΔEd) values were 1.0 kcal mol-1 with an exponential distribution for both C2H5F and C2H4F2.The (ΔEd) values for C2H5F or C2H4F2 were virtually the same and ranged from 2.0 to 5.0 kcal mol-1 for N2, CO2, and SF6; these transition probability distributions were of the Gaussian type (represented here by a stepladder model).The results for CH3CH2F and CH2FCH2F are compared to previous findings for CH3CF3 and CH2ClCH2Cl from this laboratory.The deactivation efficiency for SF6 is similar for all four molecules.However, the deactivation of CH3CF3 by N2 and CO2 is less efficient than for the other three molecules.The He deactivation efficiencies for the fluoroethanes are all similar, but substantially smaller than for C2H4Cl2.
- Richmond, G.,Setser, D. W.
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p. 2699 - 2705
(2007/10/02)
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