32753-89-2Relevant academic research and scientific papers
Kinetic and thermodynamic effects in the thermal electrocyclic ring-openings of 3-fluorocyclobutene, 3,3-difluorocyclobutene, and 3-(trifluoromethyl)cyclobutene
Dolbier,Gray,Keaffaber,Celewicz,Koronia k
, p. 363 - 367 (2007/10/02)
The synthesis and thermal electrocyclic ring-opening of 3-fluorocylobutane, 4, 3,3-difluorocyclobutane, 5, and 3-(trifluoromethyl)cyclobutane, 6, are reported. Activation energies for their ring-openings were found to be 28.1, 45.0, and 36.3 kcal/mol, respectively. 6 was found to form both the (E)- and the (Z)-5,5,5-trifluoro-1,3,butadienes, in a 95:5 ratio. Thermal equilibrations of the diene products from 4 and 6 were also carried out. The results demonstrate that a CF3 group exhibits only a slight preference for outward rotation (ΔE(a) = 1.2 kcal/mol), while a fluorine substituent gives rise to a much more dramatic outward rotational preference (ΔE(a) = 13.8 kcal/mol). These results were consistent with those previously reported for perfluorinated systems and with theoretical expectations.
REACTIONS OF HALOGEN FLUORIDES. VII. FLUORINATION OF UNSATURATED COMPOUNDS WITH BROMINE TRIFLUORIDE AND AN EQUIMOLAR MIXTURE OF BROMINE TRIFLUORIDE WITH MOLECULAR BROMINE
Boguslavskaya, L. S.,Chuvatkin, N. N.,Kartashov, A. V.,Ternovskoi, L. A.
, p. 230 - 236 (2007/10/02)
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.
