- Microscale Preparation of Isotopically Enriched 37ClHC=CHF
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Chlorination of 1-bromo-2-fluoroethylene followed by reductive dehalogenation of the produced 1-bromo-1,2-dichloro-2-fluoroethane selectively affords 1-chloro-2-fluoroethylene. This process is suitable to produce 37Cl isotopically enriched ClHC=CHF on a convenient scale (3.8 mmol).
- Baldan, Alessandro
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p. 1229 - 1235
(2007/10/03)
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- Experimental and theoretical studies of the vibrational spectra of cis-1-bromo-2-fluoroethene
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The gas-phase infrared spectrum of cis-1-bromo-2-fluoroethene has been studied at low resolution in the range 200-6500cm-1, leading to a complete assignment of the fundamentals, except the lowest vibrational mode ν9 predicted at 167cm-1. The remaining vibrational structure has been mainly interpreted in terms of first overtone or two quanta combination bands. Isotopic 79/81Br shift has been observed only in the ν8 fundamental. The equilibrium structure and the quadratic force field have been investigated theoretically at CCSD(T) level of theory employing Dunning's correlation consistent triple-zeta basis set. Cubic and semidiagonal quartic force field have been calculated using second-order M?ller-Plesset perturbation theory and Ahlrich' split valence (SV) contracted basis set. After a minor scaled quantum mechanical (SQM) adjustment of the quadratic force constants, the vibrational analysis, based on the second-order perturbation theory, has been carried out with the calculated force constants.
- Baldacci,Stoppa,Charmet, A. Pietropolli,Scaranto,Gambi
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p. 1967 - 1975
(2007/10/03)
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- REACTIONS OF HALOGEN FLUORIDES. VII. FLUORINATION OF UNSATURATED COMPOUNDS WITH BROMINE TRIFLUORIDE AND AN EQUIMOLAR MIXTURE OF BROMINE TRIFLUORIDE WITH MOLECULAR BROMINE
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The reactions of bromine trifluoride and an equimolar mixture of bromine trifluoride and bromine with halogen-substituted alkenes and methyl α-substituted acrylates were investigated.With sufficient dilution of the substrate by Freon 113 (20-25:1) it is possible to obtain the bromofluoro and difluoro adducts with good yiels.The best results (overall yields of fluorination products 80-83percent) were obtained with alkenes containing a halogen at the multiple bond; in the case of more reactive substrates the reaction becomes nonpreparative.The bromofluorination of E- and Z-1,2-dichloroethylenes and E- and Z-1,3-dichloropropenes with pure bromine trifluoride is antistereospecific.The bromofluorination of E- and Z-1,2-dichloroethylenes by the BrF3-Br2 system gives a mixture of diastereomeric bromofluoro adducts as a result of isomerization of the initial olefins in the presence of the bromine.The formation of the difluorides of the halogenated olefins is nonstereospecific and is accompanied by migration of the halogens.
- Boguslavskaya, L. S.,Chuvatkin, N. N.,Kartashov, A. V.,Ternovskoi, L. A.
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p. 230 - 236
(2007/10/02)
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- REACTIONS OF CHLORINE MONOFLUORIDE. REGIOSPECIFICITY AND STEREOCHEMISTRY OF THE SUBSTITUTION OF BROMINE ATOMS BY FLUORINE IN HALOGEN-SUBSTITUTED ALKANES AND ESTERS
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Under mild conditions without catalysts chlorine monofluoride substitutes bromine atoms for fluorine in bromine-substituted alkanes and esters.Electron-donating substituents promote the substitution reaction.The following sequence is observed in the reactivity of the bromine atoms at the carbon: tertiary > secondary > primary.Halogen atoms (Cl, F) at a carbon containing a bromine also promotes substitution of the latter by fluorine.The reactivity of the bromine atoms decreases in the following order: CCl2Br(CClFBr) > CHClBr(CHFBr) > CH2Br.An alkoxycarbonyl group at a carbon containing bromine prevents substitution.In a number of cases substitutive fluorination is accompanied by skeletal rearrangements and by migration of chlorine atoms.The stereochemistry of substitutive fluorination was studied for the case of the reaction of erythro- and threo-1-bromo-2-fluoro-1,2-dichloroethanes and 1,2-dibromo-1,3-dichloropropanes with chlorine monofluoride.The probable mechanism of the reaction is discussed.
- Boguslavskaya, L. S.,Chuvatkin, N. N.,Panteleeva, I. Yu.,Ternovskoi, L. A.
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p. 814 - 820
(2007/10/02)
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