75-63-8Relevant articles and documents
Threshold effects in electron transfer to oriented molecules
Xing, Guoqiang,Kasai, Toshio,Brooks, Philip R.
, p. 2581 - 2589 (1995)
The effects of molecular orientation on electron transfer are explored in collisions between haloalkane molecules oriented in molecular beams and K atoms which have sufficient energy to allow the charged products to separate. For several molecules studied (CF3Br, CF3Cl, and CH3Br) attack at the "heads" end of the molecule (the end with the most weakly bound atom) always produces more K+ ions. The effect of orientation is most dramatic at energies near threshold (≈5 eV) and disappears at energies of ≈20 eV, showing that steric requirements are energy dependent. Heads orientation has a lower energy threshold than tails orientation so there is a limited energy region where reaction occurs only in the heads orientation. For CF3Br, the thresholds are 3.4 and 4.0 eV, corresponding to energies required for formation of CF3Br- and CF3 + Br-, respectively. For energies between 3.4 and 4.0 eV, reaction occurs only for attack at the Br end to form only two species, suggesting that the electron is preferentially transferred to the Br end of the molecule.
Gas-phase photodissociation of CF3C(O)Cl between 193 and 280 nm
McGillen, Max R.,Burkholder, James B.
, p. 189 - 194 (2015/10/12)
Product yields were measured in the 296 K photolysis of CF3C(O)Cl at 193, 248, 254, and 280 nm. Br2 was used as a radical scavenger to convert the primary CF3 and CF3CO radical photofragments into stable bromides, CF3Br and CF3C(O)Br, which were quantified along with CO and CF2O using infrared absorption. The stabilized CF3CO radical yield increased with increasing photolysis wavelength from 3Cl quantum yield was determined to be 0.001 at all wavelengths.
Me3SiCF3/AgF/Cu - A new reagents combination for selective trifluoromethylation of various organic halides by trifluoromethylcopper, CuCF3
Kremlev, Mikhail M.,Mushta, Aleksej I.,Tyrra, Wieland,Yagupolskii, Yurii L.,Naumann, Dieter,M?ller, Angela
body text, p. 67 - 71 (2012/03/10)
An alternative copper halide-free route to obtain highly reactive trifluoromethylcopper species has been developed via the reaction of silver fluoride and trimethyl(trifluoromethyl)silane followed by a redox transmetallation with elemental copper. The composition of the reactive intermediate was investigated by means of UV/Vis/NIR, ESR, 19F NMR spectroscopy and ESI mass spectrometry. "Trifluoromethylcopper" prepared by the oxidative transmetallation route exhibits excellent reactivity and selectivity in substitutions of iodine or bromine bond to aromatic or heterocyclic compounds for trifluoromethyl groups without any additional catalyst.
The nascent OH detection in photodissociation of 2-(bromomethyl)hexafluoro- 2-propanol at 193 nm: Laser-induced fluorescence study
Indulkar, Yogesh N.,Upadhyaya, Hari P.,Kumar, Awadhesh,Waghmode, Suresh B.,Naik, Prakash D.
experimental part, p. 210 - 219 (2012/07/14)
Photodissociation of 2-(bromomethyl)hexafluoro-2-propanol (BMHFP) and 3-bromo-1-propanol (BP), involving σC-BrnBr transition at 193 nm, has been investigated by measuring laser-induced fluorescence spectra of the expected OH product. The OH channel is a minor dissociation pathway with a quantum yield of 0.17 ± 0.05 in BMHFP, whereas it was not observed in BP. Partitioning of the available energy into translation, rotation, and vibration of the photoproducts has been measured by state selective detection of the nascent OH product in BMHFP. OH is produced mostly in the ground vibrational level (v″ = 0), with a rotational distribution being characterized by a temperature of 465 ± 25 K. But, a significant fraction of the available energy of 30.2 kcal mol-1 is partitioned into translation of OH (14.6 kcal mol-1). The OH(v″ = 0, J″) populations in the spin-orbit states as well as in the Λ-doublet states are statistical. A plausible mechanism of OH formation on excitation of BMHFP at 193 nm is suggested, with the primary reaction channel being elimination of Br atom by direct C-Br bond dissociation from a repulsive surface. The Br radical is detected using (2 + 1) resonance-enhanced multiphoton ionization (REMPI) at ～234 nm. It is produced in both the ground (2P3/2) and the excited (2P1/2) spin-orbit states with the relative quantum yield of the latter to be 0.36. The co-fragment of Br undergoes secondary C-O bond dissociation to produce OH and F3C-C(CH 2)-CF3, with the reaction having a barrier located in the exit channel. In this two-step three-body dissociation process, a major fraction of the available energy is released into translation (〈fT〉 ～ 0.75), resulting from an impulsive C-Br bond dissociation in the primary step and presence of an exit barrier in the secondary process. Experimental results combined with theoretical calculations provide a clear picture of the dynamics of OH formation from BMHFP at 193 nm. In addition, the energetics of another channel, competing with OH, have been calculated from the primary product F3C-C(CH2)(OH)-CF3. In contrast to BMHFP, the OH product could not be observed from the photolysis of 3-bromo-1-propanol (another saturated halogenated propanol) at 193 nm under the detection limit of the present experimental condition, although it has a higher absorption cross-section at 193 nm.
Catalytical production processes for making hydrohalopropanes and hydrofluorobutanes
-
Page/Page column 4, (2008/06/13)
A process is disclosed for making hydrohalopropanes or hydrofluorobutanes. The process involves reacting a hydrofluoromethane with a fluoroolefin in the presence of an aluminum catalyst to produce a hydrohalopropane or a hydrofluorobutane. The hydrofluoromethane is CH2F2 or CH3F. The fluoroolefin is CF2═CF2, ClFC═CF2, or CF3CF═CF2.
Conversion of CHF3 to CH2=CF2 via reaction with CH4 and CaBr2
Han, Wenfeng,Yu, Hai,Kennedy, Eric M.,Mackie, John C.,Dlugogorski, Bogdan Z.
, p. 5795 - 5799 (2008/12/22)
Reaction of CHF3 and CH4 over CaBr2 was investigated at 400-900°C as a potential route for transforming the highly potent greenhouse gas, CHF3, into the valuable product CH 2=CF2. The homogeneous reaction of CHF3 with CH4 was also studied to assist in understanding the chemistries involved. Compared to the gas phase reaction, the addition of CaBr2 as a reactant increases the conversion of CHF3 and CH4 significantly at low temperatures while to a lesser extent at higher temperatures. In the absence of CaBr2, besides the target product, CH2=CF2, a large amount of C2F4 forms. On addition of CaBr2, the rate of formation of C 2F4 drops dramatically to near zero, while the rate of formation of CH2=CF2 increases considerably at temperatures below 880°C. Experimental and theoretical studies suggest that CHF3 strongly interacts with CaBr2, resulting in the fluorination of CaBr2 to CaF2, the release of active Br species results in the selective formation of CBrF3. The subsequent reactions involving Br, methane, and CBrF3 play a major role in the observed enhanced yield of CH2=CF2.
Reactions of H3O+ and H2O+ with several fully halogenated bromomethanes
Thomas,Kennedy,Mayhew,Watts
, p. 8489 - 8495 (2007/10/03)
The bimolecular rate coefficients and ion products for the reactions of H3O+ and H2O+ with the bromine-containing molecules CF3Br, CF2Br2, CF2BrCl, CFBr3, CFBr2Cl, and CBrCl3 at 300 K are reported. With the exception of the reactions of H3O+ with CF3Br and CF2BrCl, the rate coefficients are near the collisional values (k ≈ 10-9 cm3 molecule-1 s-1). The most efficient exit pathway for the majority of the H3O+ reactions is the formation of a trihalomethyl cation, together with water and a hydrogen halide as the neutral products. In each case, more than one trihalomethyl cation can be formed. The branching ratios are largest for the products resulting from the breaking of a C-F bond. This is attributed to the high bond strength of HF relative to HCl and HBr. Similarly for CBrCl3, the major product cation is CCl2Br+. The H2O+ reactions are found to proceed predominantly via charge transfer. For the reaction of H2O+ with CF3Br there is clear evidence for intimate reaction pathways in which bonds are broken and formed.
Facile conversion of perfluoroacyl fluorides into other acyl halides
Fukaya, Haruhiko,Matsumoto, Tomonori,Hayashi, Eiji,Hayakawa, Yoshio,Abe, Takashi
, p. 915 - 920 (2007/10/03)
Nine perfluoroacyl fluorides underwent halogen exchange when treated with anhydrous lithium halides to give acyl chlorides, bromides and iodides in high yields. The temperature dependence of this reaction is described. In the reaction with perfluorodiacyl fluoride, the diacyl halides possessing different acyl halide-groups were also produced. Of the alkaline metal salts used halogen exchange was successful only with lithium salts because of the interaction between lithium and fluorine.
Perfluoroalkyl hypobromites: Synthesis and reactivity with some fluoroalkenes
Anderson, John D.O.,DesMarteau, Darryl D.
, p. 147 - 152 (2007/10/03)
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.
Atmospheric Chemistry of CF2BrH: Kinetics and Mechanism of Reaction with F and Cl Atoms and Fate of CF2BrO Radicals
Bilde, Merete,Sehested, Jens,Mogelberg, Trine E.,Wallington, Timothy J.,Nielsen, Ole J.
, p. 7050 - 7059 (2007/10/03)
A pulse radiolysis technique was used to investigate the kinetics and products of the reaction of CF2BrH with fluorine atoms at 296 K.This reaction forms an adduct which is in dynamic equilibrium with CF2BrH and fluorine atoms.The UV absorption spectrum of the adduct was measured relative to the UV spectrum of the CH3O2 radical over the range 230-380 nm.At 280 nm, an absorption cross section of (1.3 +/- 0.3)E-17 cm2 molecule-1 was determined.From the absorption at 280 nm the equilibrium constant K5 = /() was measured to be (1.59 +/- 0.13)E-17 cm3 molecule-1.In 1 atm of SF6, the forward rate constant k5 = (1.4 +/- 0.5)E-11 cm3 molecule-1 s-1 and the backward rate constant k-5 = (8.8 +/- 3.0)E5 s-1 were determined by monitoring the rate of formation and loss of the adduct.As part of the present work a relative rate technique was used to measure k(Cl + CF2BrH) = (5.8 +/- 1.0)E-15 cm3 molecule-1 s-1 at 296 K and 700 Torr of N2.The fate of the oxy radical, CF2BrO, in the atmosphere is bromine atom elimination and formation of COF2.
