Method for producing halogen-polyfluorobenzenes
A kind of technology of fluorobenzene and polyfluorocarboxylic acid, applied in the field of preparation of halogenated benzene
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example 1
[0030] Example 1 prepares chlorofluorobenzene
[0031]
[0032] Potassium pentafluorobenzoate (100 g) was added to dimethylformamide ( 150ml). The reaction mixture was heated to 140°C, and carbon tetrachloride (154 g) was added in such a manner as to maintain a temperature of 140-143°C while distilling off the resulting product. This process continues until the end of gas evolution. The distillates and cubes were combined and washed with two volumes of 15% hydrochloric acid. The aqueous layer was decanted and the lower (organic) layer was washed with water, steam distilled and rectified. After rectification, chlorofluorobenzene (72.9g) with a purity of 99% and a boiling point of 118°C was obtained, corresponding to 90% of the chlorofluorobenzene described in [Zh.Org.Khim.11; (1975); p.2372–2383]. Yield. NMR of the obtained compound 19 F is consistent with the literature [Journal of Organic Chemistry; vol.54(23); (1989); p.5511-5516].
example 2
[0033] Example 2 Preparation of chlorofluorobenzene
[0034]
[0035] Stir in a 0.5 L glass reactor equipped with a mechanical stirrer, dropping funnel, separator, Liebig condenser, adapter and receiver flask, add potassium pentafluorobenzoate (100 g) to sulfolane (150 ml) . The reaction mixture was heated to 140°C and carbon tetrachloride (154 g) was added in such a way as to maintain the temperature of 140-160°C while distilling off the resulting product. This process is continued until the end of gas evolution. The cube was heated to 185-190°C while distilling off the resulting product. The total yield was 94 g, and the purity was 78%. After rectification, chloropentafluorobenzene (53 g) with a purity of 99% was obtained, and the yield was 66%.
example 3
[0036] Example 3 Preparation of chlorofluorobenzene
[0037]
[0038] Stir in a 0.5 L glass reactor equipped with a mechanical stirrer, dropping funnel and reflux condenser, and add potassium pentafluorobenzoate (100 g) to acetonitrile (150 ml). The reaction mixture was heated to 80°C and carbon tetrachloride (154 g) was added in this way to maintain reflux. This process is continued until the end of gas evolution. After cooling, the reaction mixture was washed with two volumes of 15% perchloric acid. The aqueous layer was decanted, the lower layer (organic) containing the precipitate was rinsed with water, 2 volumes of water were added, and the product was subjected to steam distillation followed by rectification. After rectification, chlorofluorobenzene (49 g) with a purity of 99% and a yield of 61% was obtained.
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