2π + 2π cycloaddition kinetics of some fluoro olefins and fluoro vinyl ethers

A general method for nearly reduction-free dehalogenations in a fluorinated biphasic system

“…The starting substrates (1, 2, 3 and 7) were all synthesized according to literature procedures [5,7,23,24]. All of the hydrogenated solvents were thoroughly dried by distillation over P 2 O 5 and stored over activated 4A molecular sieves and kept in a dry-box.…”

“…of 8, the fluorinated solvent Galden 1 HT-200 was substituted with Galden 1 D-100 in order to isolate it easily by distillation at reduced pressure. This is because 8 readily undergoes 2 + 2 thermal cycloaddition already at 150 8C [24,25].…”

Perfluorocyclobutyl-based methacrylate monomers: Synthesis and radical polymerization

“…It is well-known that thermal [2p + 2p] cyclodimerization of fluorinated olefins proceed via a biradical mechanism, the single requirement being the presence of a terminal difluoromethylene group in the olefin [1,19]. Therefore, three types of crossing-dimer products would be obtained after the cross-coupling reaction between p-(trifluorovinyloxy)anisole and substituted p-(trifluorovinyloxy)benzene (Scheme 3).…”

“…p-Bromo(trifluorovinyloxy)benzene (A) and p-(trifluorovinyloxy)anisole (B) were heated neat in NMR tubes and the area ratio of trans (to O) fluorine signal of A (peak b) to B (peak b 0 ) was measured as a function of time by 19 F NMR (Fig. 1).…”

Science and technology of perfluorocyclobutyl aryl ether polymers

“…5 Because of the high strain energy of the fluoroolefin, formation of the less sterically strained cyclobutane ring is thermodynamically favored. 7 For oxygen-containing fluoroolefin ethers (RÀ ÀOÀ ÀCF¼ ¼CF 2 ), the activation energy for cycloaddition is further reduced by 15À20 kcal/mol as compared with alkyl fluoroolefins (RÀ ÀCF¼ ¼CF 2 ) or halogen-containing fluorocarbons (XÀ ÀCF¼ ¼CF 2 ). [8][9][10] The thermal cyclodimerization of aryl TFVE aryl ether monomers produces stereo-random PFCB rings in primarily 1,2 fashion (i.e., head-to-head).…”