- Synthesis and aromatization of 2+2 cycloadducts of butadienes and tetrafluoroethylene
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Passing tetrafluoroethylene (TFE) and hydrocarbon dienes down a hot tube at 600 deg C with a contact time of a few seconds produces substituted fluorobenzenes.Specifically, tetrafluoroethylene and butadiene form 1,2-difluorobenzene.The aromatics produced bythe pyrolysis of TFE and methyl-substituted butadienes do not necessarily result from eliminating HF from 2+4 adducts of the starting materials.Solid-acids such as alumina or silica/alumina accelerate the ring-expansion elimination of the 2+2 cycloadducts.Aromatic products result from the preformed 2+2 cycloadducts at temperatures 200 deg C lower than the corresponding thermal reaction.The solid-acids can also influence product regiochemistry.
- Weigert, F. J.,Davis, R. F.
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- Three-step regioselective synthesis of 2,3-difluorohalobenzenes using tetrafluoroethylene and buta-1,3-diene as starting building blocks
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The gas-phase copyrolysis of tetrafluoroethylene and buta-1,3-diene in a flow tube reactor at 490–510 °C gives 3,3,4,4-tetrafluorocyclohex-1-ene, which is selectively converted to 1-bromo- or 1-chloro-2,3-difluorobenzene via intermediate steps of halogenation and dehydrohalogenation.
- Egorov, M. P.,Lipkind, M. B.,Nefedov, O. M.,Volchkov, N. V.
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p. 925 - 932
(2021/06/07)
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- Synthesis of fluorinated halonitrobenzenes and halonitrophenols using tetrafluoroethylene and buta-1,3-dienes as starting building blocks
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The gas-phase copyrolysis of tetrafluoroethylene with buta-1,3-diene in a flow reactor at 495–505 °C produces 3,3,4,4-tetrafluorocyclohex-1-ene, which selectively converted to 1,2-difluorobenzene or 1-chloro-2,3-difluorobenzene. The latter can be converted to 2-chloro-3,4-difluoronitrobenzene, 2,3,4-trifluoronitrobenzene, 2,3-difluoro-6-nitrophenol, or 2-chloro-3-fluoro-4-nitrophenol via nitration, fluorodechlorination, and hydrolysis reactions.
- Lipkind, M. B.,Nefedov, O. M.,Volchkov, N. V.
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p. 2156 - 2163
(2022/01/22)
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- KINETICS AND MECHANISM OF THE SYNTHESIS OF DIFLUOROBENZENES BY THERMAL REACTION OF DIFLUOROCARBENE WITH BUTADIENE
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Reaction of butadiene with difluorocarbene, resulting in the formation of difluorobenzenes, and its main steps have been systematically studied.The kinetics of thermal conversions of intermediately formed 2,2-difluorovinylcyclopropane and 2,2,3,3-tetrafluorovinylcyclobutane has been examined.The synthesis of difluorobenzenes has been optimized.The results obtained are used as a basis for domestic technology of production of difluorobenzenes.
- Shipilov, A. I.,Zabolot-skikh, V. F.,Nefedov, O. M.
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