Olefinic Compounds and Related Polymers

Olefinic Compounds and Related Polymers.— The synthesis and polymmiz-ation of fluorinated styrenes and phenyl vinyl ethers has been reviewed. Patent claims for the preparation of octafluorostyrmie (see Vol. 1, p. 200) have been extended to cover old work on the dehydrochlorination of (2-cMofo-l,2,2 trifluoroethyl)pentailuorobenzene with molten potassium hydroxide or with carbon pellets impregnated with potassium hydroxide. Reasonable yields of the styrene can be obtained by these methods, but the route from readily available materials is long, and a more convenient laboratory preparation involves the reaction of pentafluorophenylcopper with trifluoro-iodoethylene (55 % yield). The reaction of pentafluorophenyl-lithium with an excess of tetrafluoroethylene in ether at -20 °C also gives octafiuoro- 

Tambotski, E. J. Soloski, and R. J. De Pasquale, /. OrganometaUic Chem., 1968, 15,494 for a related coupling reaction between pentafluoroiodobenzene and l-iodo hexafluoro-2-tiifluorometh cyclopentene, see G. Camaggi and F. Gozzo, J. Chem. Soc. (O. 1971, 925 (reviewed on p. 57). 

Kinetic studies of the gas-phase pyrolysis of 1-aiylethyl acetates (ArCHMe-O COMe Ar = Ph or CeF ) have established that, at 625 K, pentafluoro-styrene is formed 4.60 times more slowly than styrene undo identical conditions. Previous results with monofluoro-compounds show that, if the effects of the fluorine atoms were additive, a retardation factor of 7.75 woidd be obsraved, and it is suggested that the five fluorine atoms are acting to some extent in opposition and that the full —I effect of each cannot be exerted. Similar conclusions have been reached as a result of studies of the u.v. spectrum of 2,3,4,5,6-pentafluoro-Malachite Green (64) (synthesized via the reaction of pentafluorophenyl-lithium with Michler s ketone), which shows a bathochromic shift of only 37 nm in the A -band with respect to the unfluorinated analogue.  

The diarylbistrifluoromethylethylenes (65) are claimed to be useful as oral contraceptives, administered to warm-blooded animals after coitus (tests with young female rats are described, the minimum EDjo dose being 0.016—0.08 mg kg- d ). The compounds are prepared either from perfluoro-isobutene or 1-arylisobutenes and aryl-lithium compounds (R = R = H  

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