- Comparative studies in the 19F and 1H NMR chemical shifts in 2,2-difluorohalogenated propanes
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Fluorine-19 chemical shifts were compared with 1H chemical shifts in CF3-CF2-R versus CH3-CF2-R, CF2Cl-CF2-R versus CH2Cl-CF2-R and CFCl2-CF2-R versus CHCl2-CF2-R, where R is a substituted methyl group containing all combinations of H, Cl and F. A good linear relationship was found between the 19F and 1H NMR chemical shifts. Conformational analysis using MNDO calculations was applied to the CF3-CF2-R and CH3-CF2-R series to clarify the interaction between the terminal substituents. In halogenated propanes, 19F and 1H chemical shifts are mainly affected by the through-space interaction between the terminal substituents rather than the electro-negativity.
- Tanuma,Ohnishi,Okamoto,Morikawa
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- PURIFICATION METHOD, PRODUCTION PROCESS, AND USE OF, 1, 1-DIFLUOROETHANE
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Crude 1,1-difluoroethane containing at least one compound selected from the group consisting of unsaturated compounds each having two carbon atoms within the molecule and saturated chlorine-containing compounds each having two carbon atoms within the molecule is brought into contact with a zeolite and/or a carbonaceous adsorbent, or crude 1,1-difluoroethane containing hydrogen fluoride and, as impurities, at least one compound selected from the group consisting of unsaturated compounds each having two carbon atoms within the molecule is brought into contact with a fluorination catalyst in a gas phase state. High-purity 1,1-difluoroethane usable as a cryogenic refrigerant, or as an etching gas, can be produced in an industrially advantageous manner.
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Page/Page column 16-17
(2008/06/13)
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- Process for the preparation of 1-chloro-1-fluoroethane and/or 1,1-difluoroethane
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The invention relates to a process for the preparation of chloro-1-fluoroethane and 1,1-difluoroethane by reaction of vinyl chloride with hydrogen fluoride, in organic solvent consisting of at least one saturated halogen-containing hydrocarbon.
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Page column 6-8; Table 1
(2008/06/13)
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- Production of organic fluorine compounds
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A process is disclosed for hydrofluorinating an olefinic hydrocarbon of the formula where X, X' and X" are the same or different and are hydrogen or halo and R' is hydrogen or C1 -C6 alkyl, with hydrogen fluoride. The process is carried out by admixing the olefinic hydrocarbon with hydrogen fluoride in an imidofluoride hydrogen fluoride solvent having the formula where R is C1 to C6 alkyl, C1 to C6 alkyl substituted with halo or C6 to C10 aryl either unsubstituted or substituted with alkyl and η is 0 or an integer that is at least 1.
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- REACTIONS OF CHLORINE MONOFLUORIDE. VI. RELATIVE RATES OF SUBSTITUTIVE FLUORINATION OF BROMINE-SUBSTITUTED ALKANES. HYDRIDE SHIFTS AND OTHER MIGRATIONS DURING FLUORINATION
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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.
- Morozova, T. V.,Chuvatkin, N. N.,Panteleeva, I. Yu.,Boguslavskaya, L. S.
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p. 1255 - 1263
(2007/10/02)
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