30301-52-1Relevant academic research and scientific papers
Thermal and UV-induced isomerisation of fluorinated hexatrienes
Hrabal, R.,Chvatal, Z.,Dedek, V.
, p. 185 - 192 (1993)
Irradiation of octafluoro-1,3,5-hexatriene (I) in the gas phase with a high-pressure mercury lamp gave a mixture of octafluoro-2-vinyl-cyclobutene (III) and octafluorobicyclohex-2-ene (V).The analogous photolysis of hexatriene I in the liquid phase led to an equilibrium mixture of the starting compound I (cis-isomer) and the trans-isomer II, respectively.Photolysis of 2,3,4,5-tetrafluro-1,3,5-hexatriene (VI) gave a mixture of cis- and trans-isomers, both in the vapour and liquid phases.Thermal reaction of hexatriene I gave octafluoro-1,3-cyclohexadiene (IV) as the sole product.
The Perfluoro-1,3,5-hexatrienes
Jing, Naiyong,Lemal, David M.
, p. 1844 - 1848 (1994)
trans-Perfluoro-1,3,5-hexatriene was obtained by catalytic isomerization of the cis isomer, and their configurations were confirmed by a photochemical method.Equilibration of these isomers with iodine and light at 13 deg C revealed that the cis isomer is slightly more stable than the trans (Kc-t = 0.83).The trienes undergo reactions under the influence of heat and light which contrast with those of their hydrocarbon counterparts.Cis triene cyclizes reversibly to perfluoro-3-vinylcyclobutene at 160 deg C (Keq = 12.2), and at higher temperatures perfluoro-1,3-cyclohexadiene is formed irreversibly.Cyclization of trans triene to the vinylcyclobutene is much slower than that of the cis isomer, as required by the finding that thermal ring opening of the vinylcyclobutene gives cis triene cleanly.Ultraviolet irradiation of the trienes with and without mercury sensitization yields the same two cyclization products, but the cyclohexadiene undergoes a further rapid photocyclization to give perfluorobicyclohex-2-ene, as reported recently by Dedek's group.Mercury photosensitization of the vinylcyclobutene proceeds smoothly to yield this same bicyclic olefin.
Novel keto-enol systems: Cyclobutane derivatives
Lindner, Patrick E.,Correa, Ricardo A.,Gino, James,Lemal, David M.
, p. 2556 - 2563 (2007/10/03)
3H-Perfluorobicyclo[2.2.0]hexan-2-one (3) has been synthesized from hexafluorobenzene and equilibrated with its enol form (4). In carbon tetrachloride K(e/k) = 0.07 ± 0.01 (25°C), but in Lewis basic solvents (e.g. acetonitrile, ether, and tetrahydrofuran) only enol is detectable at equilibrium because of its strength as a hydrogen bond donor. In the monocyclic counterpart of this keto-enol system, 2H-perfluorocyclobutanone (1) and perfluorocyclobut-1-enol (2), the enol is more stable yet. Here ketone is undetectable under equilibrating conditions in all media examined, including carbon tetrachloride. Among unhindered and unconjugated enols, 2 and 4 are more stable relative to their ketones than any others that have been reported. Ab initio quantum mechanical calculations support the conclusion that destabilization of the ketones, but not stabilization of the enols, by fluorine substitution is responsible for the unique relative stability of these enols.
