双分子水和氨气催化CF3OH分子裂解的理论研究

The G3 and CBS-QB3 theoretical methods are employed to study the decomposition of CF₃OH into FCFO and HF by water, water dimmer, and ammonia. The decomposition of CF₃OH into FCFO and HF is unlikely to occur in the atmosphere due to the high activated energy of 88.7 kJ/mol at the G3 level of theory. However, the computed results predict that the barrier for unimolecular decomposition of CF₃OH is decreased to 25.1 kJ/mol from 188.7 kJ/mol with the aid of NH₃ at the G3 level of theory, which shows that the ammonia play a strong catalytic effect on the split of CF₃OH. In addition, the calculated rate constants show that the decomposition of CF₃OH by NH₃ is faster than those of H₂O and the water dimmer by 109 and 105 times respectively. The rate constants combined with the corresponding concentrations of these species demonstrate that the reaction CF₃OH with NH₃ via TS4 is of great importance for the decomposition of CF₃OH in the atmosphere.     

Perfluoralkyljod-verbindungen: das trifluormethyljoddinitrat CF3J(NO3)2

CF₃I(NO₃)₂ is formed from the reactions of CF₃IF₂ or CF₃IO with N₂O₅ as well as CF₃I with ClNO₃. During the reactions of CF₃IF₂ with N₂O₅ or CF₃I with ClNO₃ the intermediate products CF₃IF(NO₃) or CF₃ICl(NO₃) can be identified. The preparations, properties, ¹⁹F-nmr spectra and the thermal decomposition of CF₃I(NO₃)₂ are described.     

Perfluoralkyljod-verbindungen: Darstellungen und eigenschaften von CF3JO,CF3JOF2 und CF3JO2

Perfluoroalkyl iodine compounds: preparations and properties of CF₃IO, CF₃IOF₂, and CF₃IO₂. The trifluoromethyl iodine compounds CF₃IO, CF₃IOF₂, and CF₃IO₂ are formed from the reactions of CF₃I, CF₃IF₂ or CF₃IF₄ with ozone or silicon dioxide respectively. Their preparartions, properties, ¹⁹F-nmr spectra, and ir spectra are described.     

Novel ammonium hexafluoroarsenate salts from reaction of (CF3)2NH,CF3N(OCF3)H,CF3N[OCF(CF3)2]H,CF3NHF and SF5NHF with the strong acid HF/ASF5.

Reactions of the fluorinated amines (CF₃)₂NH, CF₃N(OCF₃)H, CF₃N[OCF(CF₃)₂]H, CF₃NHF and SF₅NHF with the strong acid HF/AsF₅ form the corresponding ammonium salts R_f¹R_f²NH₂⁺AsF₆^? and R_fNFH₂⁺ AsF₆^? in high yield. [R_f¹=CF₃, R_f²=CF₃, CF₃O, (CF₃)₂CFO; R_f=CF₃, SF₅] The colorless crystalline solids are stable for prolonged periods at 22°C in sealed FEP containers. They have dissociation pressures at 22°C ranging from ～5 torr (R_fNFH₂⁺ AsF₆^?) to ～50 torr [CF₃N(OCF₃)H₂⁺AsF₆^?]. ¹⁹F NMR and Raman spectroscopy were used to identify the compounds.     

Broadening Of The CF3I UV Absorption Spectrum BY CO2-Laser-Induced Vibrational Excitation

Absorption of CO₂ laser photons by CF₃I leads to a broadening of the CF₃I UV absorption band near 270 nm. The fwhm is increased by a factor of ≈2.3 for CO₂ laser fluence of 0.4 J/cm². Significant increase in the bandwidth is accompanied by partial decomposition of the CF₃I.     

Isotopic selectivity in the sensitized dissociation of SF5Cl and CF3I by multiphoton excitation of SF6

The dissociation of SF₅Cl and CF₃I sensitized by multiphoton excitation of SF₆ by a pulsed CO₂ laser has been studied versus pressure, laser fluence, inert gas and optical frequency. Isotopic effects have been observed between ³²SF₅Cl/³³SF₅Cl and between ¹³CF₃I/¹²CF₃I and selectivity factors as high as α^?1_{$\text{33}\text{32}$} = 1.57 or α_{$\text{13}\text{12}$} = 1.23 obtained.     

Photofragmentation of CF3I in the A band

CF₃I is photodissociated in a molecular beam with 248 nm laser lighl. Fragmentation takes place into CF₃ and I(²P_3/2) or I(²P_1/2). The quantum yield for excited I (I* = I(²P_1/2)) formation is determined to be 0.92. The CF₃ fragments are found to be considerably vibrationally excited. Of the available energy in the CF₃ + I* channel 39% (0.69 eV) appears on the average as vibrational energy in the CF₃ radical. The angular distributions in both channels show predominantly parallel character. It can be concluded that at this wavelength 97% of the total absorption is due to the ³Q₀ ← ¹A₁ transition and only 3% to the ¹Q ← ¹A₁ transition. Most of the signal in the CF₃ + I channel originates from an effective crossing between the ³Q₀ and ¹Q states. A coupled channel calculation is performed to obtain a better insight into the dissociation dynamics of the CF₃I molecule. The results indicate that the CF₃ fragments from dissociation of CF₃I at 248 nm may be expected to be vibrationally excited. However, the experimental distribution has a higher average energy and is much broader. An explanation for this phenomenon is suggested.     

Trifluoromethylsilane,CF3SiH3

CF₃SiH₃ (I) has been obtained in ～90 % yield from the reaction of CF₃SiF₃ or CF₃SiF₂I with LiAlH₄ in dibutyl ether at ?78°. (I) has been characterized by its ¹H, ¹⁹F, ¹³C and ²⁹Si NMR-, mass-, IR- and Raman spectra. It is thermally stable up to 180° and not attacked by O₂, H₂O and H₃PO₄, but cleaved by aqueous alkali. From a rovibrational analysis, B_o = 0.09769(2) cm^?1 is deduced, and a long SiC bond, 1.95(1)Å, is predicted.     

Perfluoralkyljod-verbindungen: das trifluormethyljod-bis-trifluoracetat CF3J(OCOCF3)2

CF₃I(OCOCF₃)₂ is formed from the reactions of CF₃IF₂ or CF₃IO with trifluoroacetic anhydride at low temperature. During the reaction of CF₃IF₂ with (CF₃CO)₂O CF₃IF(OCOCF₃) is formed as an intermediate product. The preparation, the ¹⁹F-nmr spectra and the thermal decomposition are described.     

Studies on sulfinatodehalogenation: III. The sulfinatodeiodination of primary perfluoroalkyl iodides and α,ω-perfluoroalkylene diiodides by sodium dithionite

Using P. T. C. or cosolvents, both perfluoroalkyl iodides such as Cl(CF₂),_nI (n=2, 4, 6, 1a-1c), H(CF₂)₈I (1d), CF₃(CF₂)_nI (n=3, 5, 7, 1e-1g), and α. ω-perfluoroalkylene diiodides such as (ICF₂CF₂)₂O (4a), I (CF₂)_nI (n=6, 8, 10, 4b-4d) reacted smoothly with sodium dithionite in aqueous solution under mild conditions to give the corresponding perfluoroalkanesulfinates Cl(CF₂)_nSO₂Na (n=2, 4, 6, 2a-2c), H(CF₂)₈SO₂Na (2d), CF₃(CF₂)nSO₂Na (n=3, 5, 7, 2e-2g), α, ω-perfluoroalky-lenedisulfinates O (CF₂CF₂SO₂K)₂ (5a), and KO₂S(CF₂)_nSO₃K (n=6, 8, 10, 6b-6d) in moderate to high yields. These sulfinates were converted to the corresponding sulfonyl chlorides by reacting with chlorine in the usual way. Thus the discovery of the new reagent renders sulfinatodeiodination a practical method for the synthesis of perfluorosulfinic and perfluorosulfonic acids and their derivatives from the corresponding perfluoroalkyl iodides.     

Syntheses and properties of cyanamide and cyanoguanidine complexes of platinum(II). X-Ray structure of trans-[Pt(CF3)(NCNEt2)(PPh3)2][BF4]

Complexes trans-[PtX(L)(PPh₃)₂]A [1: X = CF₃; A = BF₄; L = NCNH₂, NCNMe₂, NCNEt₂, or NCNC(NH₂)₂. 2: X = Cl; A = BPh₄; L = NCNMe₂ or NCNEt₂] and cis-[PtCl(L)(PPh₃)₂][BPh₄] [3: L = NCNH₂ or NCNC(NH₂)₂], which appear to be the first cyanamide or cyanoguanidine complexes of platinum to be reported, have been prepared by treatment of trans-[PtBr(CF₃)(PPh₃)₂] (in CH₂Cl₂/acetone and in the presence of Ag[BF₄]) or of cis-[PtCl₂(PPh₃)₂] (in THF and in the presence of Na[BPh₄]), respectively, with the appropriate substrate. In KBr pellets or in solution 1 (L = NCNMe₂ or NCNEt₂) undergoes ready replacement of the organocyanamide (under the trans influence of CF₃) by bromide to regenerate trans-(PtBr(CF₃)(PPh₃)₂]. The X-ray structure of 1 (X = CF₃, A = BF₄, L = NCNEt₂) is also reported, and shows the presence of two apical intramolecular contacts of the metal with two ortho-hydrogen atoms of the phosphines, whereas the amine N atom of the diethylcyanamide is trigonal planar in the linear NCN framework with a delocalized π system.     

Direct measurement of CF3I multiphoton dissociation yield by iodine-laser detection of iodine atoms

The primary yield of CF₃I multiphoton dissociation under CO₂-laser irradiation has been determined by direct monitoring of iodine atoms using a pulsed iodine laser. The primary yield was found to exceed markedly an observed MPD yield obtained from measurement of the CF₃I consumption not only in CF₃I-N₂ but also in CF₃I-O₂ mixtures.     

The addition of (CF3SO2)2CHBr to vinylidene fluoride

It has been found that a mixture of (CF₃SO₂)₂CH₂ and (CF₃SO₂)₂CBr₂ can be used instead of (CF₃SO₂)₂CHBr in the radical addition to H₂CCF₂; the 1:1 and 1:2 adducts have been isolated and characterized. An improved synthesis of (CF₃SO₂)₂CBr₂ is also reported.     

Comparative performance of CF3I,CD3I and CH3I in an atomic iodine photodissociation laser

We have compared the performance of CF₃I, CD₃I, and CH₃I in an atomic iodine photodissociation laser over the pressure range 1–200 torr. At pressures below 5 torr, CD₃I produces larger energy outputs, while above 5 torr CF₃I gives superior performance. The crossing of the laser energy output versus pressure curves is explained on the basis of collisional quenching of I(²P_{$\text{1}\text{2}$})(≡I^*) by undissociated alkyl iodide.     

Vergleich der trifluormethylierungseigenschaften von(CF3)Hg,CF3I und (CF3)2te am beispiel der reaktionen mit cyclohexen,benzol und pyridin

The trifluoromethylation reactions of (CF₃)₂Hg, CF₃I and (CF₃)₂Te with cyclohexene, benzene and pyridine are compared under similar conditions. Photochemical as well as thermal reactions result in an increase of the reactivity in the series (CF₃)₂Hg < CF₃I ? (CF₃)2Te. The yields and the kind of products vary depending on the time of irradiation and the temperature. In all cases the best yields are obtained from the thermal reactions with (CF₃)₂Te. With cyclohexene only trifluoromethylated addition products are observed. The substitution reactions with pyridine yield a mixture of isomeric trifluoromethylpyridines. (CF₃)₂Hg and CF₃I react with benzene to yield only benzotrifluoride C₆H₅CF₃. The main product of the reaction of (CF₃)2Te with benzene is also benzotrifluoride; in addition to this the disubstituted bis(trifluoromethyl)benzene isomers and trifluoromethyl- cyclohexadienes are formed. ¹H, ¹⁹F n.m.r. and mass spectra are described.     

Vibrational satellite of Na(3d ← 3s) dipole-forbidden transition in Na/CF4 mixture

Excitation spectra of Na fluorescence in mixtures with CF₄ display a new band shifted by the energy of one-vibrational quantum of the IR active ν₃-mode of CF₄ (1281 cm⁻¹) from Na 3d states. This band is attributed to a Na(3s)CF₄(ν₃ = 0) → Na(3d)CF₄(ν₃ = 1) transition and its intensity is explained by coupling with Na(4p)CF₄(v₃ = 0) resonance state which lies  180 cm⁻¹ below in energy. An analogous satellite of the Na 6p state combined with the same vibration and lying close to the Na 7p state is reported and discussed.     

Untersuchung des Systems Na/La/NH3

Inhaltsübersicht. Im System Na/La/NH₃ warden Amidpräparate durch Umsetzung der Metalle Na und La mit Ammoniak bei 3000–5000 atm NH₃-Druck und bei Temperaturen von 250–500°C dargestellt. Das Molverhältnis der Ausgangsmetalle reichte von Na: La = 9:1 bis 1:2. Na₃La(NH₂)₆ ließ sich mit einer röntgenographischen Einkristalluntersuchung charakterisieren: A = 22,11 ± 0,01 Å, b = 11,15 ± 0,01 Å und c = 7,375 ± 0,006 Å; N = 8, Fddd (Nr. 70). Neben dieser Verbindung und dem binären Amid des Lanthans existiert wahrscheinlich bei tiefen Reaktions-temperaturen ein schlecht kristallisierendes Na-ärmeres Amidometallat. Die thermische Zersetzung von Amidpraparaten (Na: La = 3:1 und 1:1) führte zu zwei mikro-kristallinen ternaren Phasen, einem Amid — Imid sowie zu einem Imid — Nitrid; als Endprodukte ergaben sich LaN neben unzersetztem NaNH₂. Investigation of the System Na/La/NH₃ Abstract. In the system Na/La/NH₃ amides were prepared by the reaction of the metals Na and La with ammonia. The ammonothermal synthesis was used starting with a molar ratio of the metals ranging from Na: La = 9:1 to 1:2 at NH₃-pressures from 3000 to 5000 atm and temperatures from 250 to 500°C. Na₃La(NH₂)₆ was characterized by an x-ray single crystal inv estigation: A = 22.11 ± 0.01 Å, b = 11.15 ± 0.01 Å, and c = 7.375 ± 0.006 Å; N = 8, Fddd (No. 70). Beside this compound and the binary Lanthanum amide another bad crystallizing compound with a lower sodium content may exist. The thermal degradation of the amides (Na: La = 3:1, and 1:1) led to two microcrystalline ternary phases, an amide – imide and an imide – nitride; binary LaN and undecomposed NaNH₂ are the endproducts.     

Sodium dithionite initiated addition of CF2Br2, CF3I and (CF3)2CFI to allylaromatics: Synthesis and the reactivity of 4-aryl-1,1-difluorodienes and 4-aryl-1,1-bis(trifluoromethyl)dienes

Sodium dithionite initiated addition of CF₂Br₂, CF₃I and (CF₃)₂CFI to the terminal double bond of allylbenzenes and of (CF₃)₂CFI to allylpyridines in a MeCN/H₂O system were investigated. The reactions of CF₂Br₂ with allylbenzenes gave comparable amounts of adducts, 1-(2,4-dibromo-4,4-difluorobutyl)benzenes, debrominated products,1-(4-bromo-4,4-difluorobutyl)benzenes, and dimeric compounds in total yields 40-66%. Treatment of the adducts with DBU resulted in double dehydrohalogenation affording 4-aryl-1,1-difluorobutadienes which undergo Diels-Alder condensation with nitrogen dienophiles to give N-heterocycles with difluoromethylene group in the ring. The reactions of CF₃I and (CF₃)₂CFI with allylbenzenes gave the respective adducts, (4,4,4-trifluoro-2-iodobutyl)benzenes and 1-(4,5,5,5-tetrafluoro-4-(trifluoromethyl)-2-iodopentyl)benzenes as the main products. Dehydrohalogenation of these adducts resulted, respectively, in (4,4,4-trifluoro-but-1-enyl)benzenes and 4-aryl-1,1-bis(trifluoromethyl)butadienes in high yields. (CF₃)₂CFI reacted rapidly with allylpyridines to give mixtures from which, after treatment with DBU, 4-pyridyl-1,1-bis(trifluoromethyl)butadienes were isolated in a ca. 60% yield.     

Synthesis and characterization of trans -Mo(CO)4( p -C5NH4SO3Na)2

Reaction between Mo(CO)₆ and p-C₅NH₄SO₃Na (1:2 (Mo: p-C₅NH₄SO₃Na) stoichiometric ratio) gave the trans-Mo(CO)₄(p-C₅NH₄SO₃Na)₂ complex, (1), in 80% yield. Complex (1) has been characterized by FTIR, ¹H and ¹³C NMR spectroscopy. Complex (1) has most likely an idealized D_4h geometry with trans N-bound p-C₅NH₄SO₃Na ligands.     

Direct dynamics studies for the reactions of CF3CHFCF3 and CF3CF2CHF2 with H atoms

The rate constants of the hydrogen abstraction reactions of CF₃CHFCF₃ + H (R1) and CF₃CF₂CHF₂ + H (R2) have been calculated by means of the dual-level direct dynamics method. Optimized geometries and frequencies of stationary points and extra points along the minimum-energy path (MEP) are obtained at the MPW1K/6-311+G(d,p) level, and the classical energetic information is further corrected with the interpolated single-point energy (ISPE) approach by the G3(MP2) level of theory. Using the canonical variational transition state theory (CVT) with small-curvature tunneling corrections (SCT), the rate constants are evaluated over a wide temperature range of 200-2000 K. The calculated CVT/SCT rate constants are in good agreement with available experimental values. It is found that the variational effect is very small and almost negligible over the whole temperature region. However, the small-curvature tunneling correction plays an important role in the lower temperature range. Furthermore, the heats of formation of species CF₃CF₂CHF₂ (SC₁ or SC₂) and CF₃CF₂CF₂ are studied using isodesmic reactions to further elucidate the thermodynamic properties.