CF3CO2ZnEt-mediated highly regioselective rearrangement of bromohydrins to aldehydes

A highly efficient and selective rearrangement reaction of bromohydrins to aldehydes mediated by CF₃CO₂ZnEt was described. The secondary and tertiary aldehydes were prepared under mild conditions in good to excellent yields (85-99%). The scope and limitations of this rearrangement process were also investigated.     

AB initio molecular orbital studies of CF3O2H,CF3O2F and CF2(OF)2

Ab initio calculations employing an extended 4-31G basis set have been applied to the highly fluorinated molecules, CF₃O₂H, CF₃O₂F and CF₂(OF)₂. Partial geometry optimizations have also been carried out on these molecules allowing a comparison between theory and the recently completed gas-phase electron diffraction results. The O-O bond distance in CF₃O₂ H is found to be longer (by 0.02 Å) than the corresponding bond in CF₃O₂F while the CO bond is found to be shorter (by 0.02 Å) in CF₃O₂H. The OF bond in CF₃O₂F is found to be longer (by 0.03–0.04 Å) than the corresponding bond in CF₃OF or F₂O. Torsional barriers have been computed for CF₃O₂H and CF₃O₂F with the aid of Fourier analysis of the potential curves. CF₃O₂H is found to have a torsional potential about the peroxide bond rather similar to that found for H₂O₂ while in CF₃O₂F the cis and trans barriers are predicted to be much larger (14.6 and 8.4 kcal mol^?1, respectively). The threefold barrier to rotation of the CF₃ group in CF₃O₂F is predicted to be 4.4 kcal mol^?1. Various conformations of CF₂(OF)₂ have also been studied with conformations consistent with the operation of the gauche-effect being most stable. Bond separation energies and molecular properties have also been computed for these molecules.     

Spectral bandshape and intensity of the C-H chromophore in the infrared spectra of CF3H and C4F9H

The vapour phase IR spectra and integrated band intensities of the fundamental and first-overtone transition of the C-H chromophore in CF₃H and (CF₃)₃CH are reported. The vibrational coarse bandshapes for (CF₃)₃CH are consistent with lorentzians of width Γ = 3 cm^?1 (fundamental) and Γ = 12 cm^?1 (overtone). The results are discussed in connection with time-dependent molecular processes and IR photochemistry.     

氟磺酸改性磺酸型聚合物催化剂在甲醛羰基化中的性能研究

采用水热合成、原位磺化法制备了固体磺酸型聚合物PDS-1.0催化剂,以三氟甲烷磺酸对其进行接枝改性得到PDS-1.0-F催化剂;采用N₂吸附-脱附、TG、FT-IR、³¹P M AS NMR和XPS等技术对催化剂的物理和化学性质进行了表征,以甲醛羰基化制乙醇酸为探针反应对其催化性能进行了评价研究。结果表明,与PDS-1.0催化剂相比,氟磺酸改性后的PDS-1.0-F催化剂的比表面积、孔容积和酸量均降低,但是酸强度和热稳定性显著增加,由此对甲醛羰基化反应具有较好的催化性能,乙醇酸收率达到91.2%。     

Copper-mediated oxidative trifluoromethylthiolation of aryl boronic acids with CF3CO2Na and elemental sulfur

A practical three-component copper-mediated oxidative trifluoromethylthiolation of aryl boronic acids with cheap and readily available sodium trifluoroacetate and elemental sulfur is reported. A variety of trifluoromethylthio-substituted aromatics are synthesized in moderate yields under mild reaction conditions.     

Ab initio direct dynamics studies on the hydrogen abstraction reactions of CF2H2 and CF3H with F atom

The dynamic properties of the hydrogen abstraction reactions of CF₂H₂ and CF₃H with F atom are investigated in the temperature range of 182–2000 K. The minimum-energy path (MEP) is optimized at MP2/6-311 G(d, p) level, then the energy profiles are refined at the CCSD(T)/6-311++G(3df, 2pd) level (single-point). The theoretical rate constants, which are calculated by the variational transition state theory (VTST) including the small curvature tunneling (SCT) correction, are in good agreement with the experimental ones. It is found that the rate constant of the CF₂H₂ + F reaction are larger than that of the CF₃H + F reaction and the activation energies exhibit in the just opposite order. This phenomenon can be rationalized by the hardness η of the halomethane molecules. The comparison of the two reactions with the CFH₃ + F reaction is made. It is found that the rate constants decrease in the order of CFH₃ + F > CF₂H₂ + F > CF₃H + F. The effect of fluorine substitution leads to a dramatic increase in the activation energy and a decrease in the preexponential factor. We hope that present theoretical studies for these compounds can give further information concerning how fluorine substitution affects the rate constants of hydrogen abstraction reactions.     

Molecular structure of van der Waals complex of o- and m-methylaniline with CF3Cl, CF3H, CF4 and CH4 studied by laser induced fluorescence spectroscopy and ab initio calculations

The excitation LIF spectra of van der Waals complexes of o- and p-methylaniline and CF₃Cl, CF₃H, CH₄ and CF₄ in a supersonic free jet are reported. The spectra show a resolved structure characteristic due to the internal rotational transitions of the methyl group. The equilibrium geometries in the ground state of the complexes have been calculated at MP2/6-31+G^∗ level of calculation and the intermolecular interaction have been discussed.     

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.     

Kationische Polymerisation von Styrolen mit Protons?uren und deren Derivaten. 2. Mitt. Zwei Wachstums-Spezies bei der Polymerisation mit CF3SO3H

Ohne Zusammenfassung     

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.     

Deactivation of vibrationally excited CD3H using laser-induced fluorescence

Infrared fluorescence observed after exciting to ν₆ (ν=1) of CD₃H with a Q-switched CO₂ laser yields the exponential deactivation rate constant of 0.84 ms^?1 torr^?1. Rate constants for deactivation of CD₃H by rare gases vary from 1.4 (for He) to 0.029 (for Xe) ms^?1 torr^?1.     

Dimerization of methyl acrylate by homogeneous transition metal catalysis. Part II. Activation of dihydridoruthenium(II) phosphane complexes by CF3 3H

The tail-to-tail dimerization of methyl acrylate (MA) in the presence of H₂Ru(PPh₃)₄ (1) or H₂(CO)Ru(PPh₃) ₃ (2) and CF₃SO₃H to give a mixture of linear dimers is described. In neat methyl acrylate at 85°C the reaction shows turnover numbers of 300 in 20 h and 640 in 7 d. Mechanistic studies show that the initial step of the reaction is the reduction of H₂Ru(PPh₃)₄ (1) by MA to form Ru(MA)₂ (PPh₃)₂ (5). After activation with CF₃SO₃H the catalytically active species contains only one phosphane ligand. The basic mechanistic features of the dimerization reaction have been revealed by ²H NMR spectroscopy involving the use of CF₃SO₃D. The deuterium-labelling studies indicate the intermediate formation of a ruthenium(II) hydride complex. Subsequent olefin insertions in this complex, followed by β-hydride elimination,lead to the linear dimeric products.     

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.     

Kationi-sche Polymerisation von Styrolen durch Protons?uren und deren Derivate. 4. Mitt. Homo- und Copolymerisationen von p-substituierten Styrolen mit CF3SO3H

Ohne Zusammenfassung     

Darstellung und eigenschaften von octafluorbutansulfonsäure H(CF2)4SO3H und einigen ihrer derivate

Perfluorobutanesulfonyl fluoride C₄F₉SO₂F, obtained by electrofluorination of sulfolene, may contain up to 10 % of perfluorotetramethylene sulfone. Upon hydrolysis with base, this sulfone yields octafluorobutanesulfonate ion H(CF₂)₄SO^ø₃ (V). Perfluorobutanesulfonic acid and octafluorobutanesulfonic acid (VI) which are readily obtained from the salts and H₂SO₄ can be separated via fractional distillation. VI forms a crystalline monohydrate, M.P. 45°C. The trimethylsilyl ester was obtained from VI and (CH₃)₃ SiCl. Upon heating above 250° the K sulfonate (Vb) liberates HF.     

Trifluoromethylperoxyphoshoryl difluoride,CF3OOPOF2 and trifluoromethoxyphosphoryl difluoride,CF3OPOF2

The new compounds CF₃OOPOF₂ and CF₃OPOF₂ have been prepared by the reaction of trifluoromethyl-hydroperoxide, CF₃OOH, with μ-oxo-bis-(phosphoryl difluoride), P₂O₃F₄, and difluorophosphine-μ-oxo-phosphoryl difluoride, P₂O₂F₄. Infrared and NMR spectra, physical properties and some chemical reactions are reported for the compounds.     

Spectroscopic investigations of CF3Se-derivatives

The vibrational spectra of CF₃SeH, CF₃SeD, CF₃SeCl, CF₃SeBr, CF₃SeCN, CF₃SeCl₃, (CF₃)₂Se and (CF₃Se)₂ are reported, and vibrational assignments presented. N.m.r. parameters for a wide range of CF₃Se-derivatives are tabulated.     

Normal coordinate analysis of CF3CH3

Normal coordinate calculations were made for CF₃CH₃, using a twenty-two parameter modified valence force field. Thirteen force constants were constrained to the CF₃CH₂X values and nine were adjusted to fit the twelve frequencies, resulting in an average error of 2.3 cm^/t-1. The CF₃ group force constants should be useful in calculations for other compounds containing this group.     

High-pressure structure of Li2CO3

The high-pressure behavior of Li₂CO₃ is studied up to 25 GPa with synchrotron angle-dispersive powder X-ray diffraction in diamond anvil cells and synthesis using a multi-anvil apparatus. A new non-quenchable hexagonal polymorph (P6₃/mcm, Z=2) occurs above 10 GPa with carbonate groups in a staggered configuration along the c-axis—a=4.4568(2) Å and c=5.1254(6) Å at 10 GPa. Two columns of face-shared distorted octahedra around the Li atoms are linked through octahedral edges. The oxygen atoms are coordinated to one carbon atom and four lithium atoms to form a distorted square pyramid. Splittings of X-ray reflections for the new polymorph observed above about 22 GPa under non-hydrostatic conditions arise from orthorhombic or monoclinic distortions of the hexagonal lattice. The results of this study are discussed in relation to the structural features found in other Me₂CO₃ carbonates (Me: Na, K, Rb, Cs) at atmospheric conditions.