430-54-6Relevant academic research and scientific papers
REACTION OF ORGANIC COMPOUNDS WITH SF4-HF-HALOGENATING SYSTEM VII. REACTIONS OF OLEFINS WITH THE SF4-HF-Cl2(Br2) SYSTEM
Kunshenko, B. V.,Mokhamed, Nagib Mukhtar,Omarov, V. O.,Muratov, N. N.,Yagupol'skii, L. M.
, p. 511 - 518 (2007/10/02)
Under the influence of the SF4-HF-Cl2(Br2) system halogen-containing olefins undergo conjugate halogenofluorination.It was shown for the case of (Z)- and (E)- 1,2-dichloroethenes that these reactions take place anti-stereospecifically through the formation of the bromonium ions.The accumulation of chlorine atoms in the olefin molecule hinders electrophilic addition of stoichiometric equivalents of ClF and BrF at the double bond.The SF4-HF-Br2 system is an effective agent for substitutive fluorination of organic compounds containing bromine.Only the bromine atoms situated at the secondary carbon atom are substituted by fluorine.
REACTIONS OF CHLORINE MONOFLUORIDE. VI. RELATIVE RATES OF SUBSTITUTIVE FLUORINATION OF BROMINE-SUBSTITUTED ALKANES. HYDRIDE SHIFTS AND OTHER MIGRATIONS DURING FLUORINATION
Morozova, T. V.,Chuvatkin, N. N.,Panteleeva, I. Yu.,Boguslavskaya, L. S.
, p. 1255 - 1263 (2007/10/02)
The relative rates of substitutive fluorination of bromoalkanes with various structures by chlorine monofluoride in a nonpolar medium at 20-40 deg C were investigated by the method of competing reactions.Halogen atoms vicinal with the substituted bromine greatly reduce the fluorination rate.The reactivity of the secondary bromides decreases in the order (CH3)2CHBr>>CH3CHBrCH2Cl>>CH2ClCHBrCH2Cl.The geminal halogen atoms have little effect on the rate of substitutive fluorination.The fluorination rates of the bromoalkanes CH2BrCH2Br, CH2BrCHClBr, and CH2BrCCl2Br are in ratios 10:3:1 respectively, while the fluorination rate of CH3CHClBr is much higher than that of CH2ClCH2Br.As a rule the debromination of primary bromides containing vicinal halogens (Br, Cl) is accompanied by migration of the latter and gives fluorides with iso structures.Hydride shifts take place in cases where stable tertiary or secondary carbocations are formed as a result of migration of the hydride; for example, the fluorination of CH3CHFCH2Br leads to the geminal difluoroalkane CH3CF2CH3.The mechanism of substitutive fluorination is discussed.
