Two perhalo-1,4-dioxins, representatives of a previously unknown class of compounds, have been synthesized and shown to exhibit unusual reactivity. In particular, reaction with oxygen is spontaneous and exothermic, and radical-catalyzed homopolymerization will proceed through a fluorinated double bond. Representatives of the perhalo-2,3-dihydro-1,4-dioxin class have also been prepared and found to have reactivity in general intermediate to that of the perhalodioxoles and acyclic trifluorovinyl ethers. Computational studies of the two systems established that introduction of the first double bond raises the energy substantially, while the second double bond results in a near-planar ring with dramatically increased energy content.
Two perhalo-1,4-dioxins, representatives of a previously unknown class of compounds, have been synthesized and shown to exhibit unusual reactivity. In particular, reaction with oxygen is spontaneous and exothermic, and radical-catalyzed homopolymerization will proceed through a fluorinated double bond. Representatives of the perhalo-2,3-dihydro-1,4-dioxin class have also been prepared and found to have reactivity in general intermediate to that of the perhalodioxoles and acyclic trifluorovinyl ethers. Computational studies of the two systems established that introduction of the first double bond raises the energy substantially, while the second double bond results in a near-planar ring with dramatically increased energy content.
Cyclisierungen unter beteiligung von fluoridionen, 3. Mittell. [1,2] teilfluorierte 1.3- und 1.4-dioxane
作者:Guenter Siegemund、Warner Schwertfeger
DOI:10.1016/s0022-1139(00)81237-3
日期:1982.10
Cyclization of 2-(2-chloroethoxy)-perfluorocarboxylic acid halides 3 with alkalimetalfluoride gives 2.3-perfluoro- 1.4-dioxanes 6 with yields up to 84 %. This reaction is also used for the preparation of 4.5.6-perfluoro-1.3- dioxanes 12 starting from 3-chloromethoxyperfluorocarbonyl compounds 11. — The preparation of starting materials is described.
This invention is directed to halodihydrodioxins, their preparation and their polymers, which provide amorphous homopolymers that are resistant to ring opening side reactions. The resulting polymers can be used for films and thermally stable molded objects, coatings for substrates such as wood, glass, paper and metal and for protective packaging. This invention also concerns the preparation of polyhalogenated dioxoles.