Process for the manufacture of halogenated hydrocarbons
AssigneeImperial Chemical Industries PLC
InventorsJohn Crosby, Bernard W. H. Terry
Life of this patent
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Abstract
2,2-Dichloro-5-methyl-1,1,1-trifluorohex-4-ene, an intermediate in the synthesis of pyrethroid insecticides, is obtained by continuous distillation, preferably under sub-atmospheric pressure, of a mixture of 5-methyl-2,2,4-trichloro-1,1,1-trifluorohexane, dimethylformamide and lithium bromide, precipitating the chlorofluorocarbons from the distillate with water and separating the desired product from starting material by a further distillation.
Claims7
A process for the manufacture of 2,2-dichloro-5-methyl-1,1,1-trifluorohex-4-ene which comprises continuously distilling a mixture of 5-methyl-2,2,4-trichloro-1,1,1-trifluorohexane, dimethylformamide and lithium bromide, collecting a distillate comprising dimethylformamide, 5-methyl-2,2,4-trichloro-1,1,1-trifluorohexane, 2,2-dichloro-5-methyl-1,1,1-trifluorohex-4-ene and hydrohalide salts of dimethylene, precipitating the chlorofluorocarbons from the distillate by adding water to the distillate and isolating the 2,2-dichloro-5-methyl-1,1,1-trifluorohex-4-ene from the precipitated chlorofluorocarbon mixture by distilling said mixture.
Dependencies are inferred from the claim text.