74415-69-3Relevant academic research and scientific papers
Extremely facile ring inversion and rearrangement in fluorobicyclo[2.1.0]pentanes
Wei, Yanjun,Liu, Yufa,Wong, Terrence,Lemal, David M.
, p. 688 - 703 (2008/09/16)
cis-1,2,3,4,5,5-Hexafluorobicyclo[2.1.0]pentane and 1,2,4,5-tetrafluorobicyclo[2.1.0]pentane have been synthesized from hexafluorobenzene. The former hydrofluorocarbon, which exists entirely in the endo configuration, rearranges to cis-1,2,3,3,4,5-hexafluorocyclopentene below room temperature (Ea = 21.9 kcal/mol, log A = 13.4). The latter undergoes degenerate ring inversion with extraordinary ease (ΔG? = 6.8 ± 0.2 kcal/mol at -55 °C). Density functional calculations indicate that significant bonding between the bridgehead carbons is retained in the ring inversion transition state. Analogous calculations predict for hexafluorobicyclo[1.1.0]butane a considerably lower barrier for ring inversion and more 1,3-bonding in the transition state.
Valence-bond isomer chemistry. Part 13. Photochemical oxidation of hexafluorobenzene: formation of hexafluoro-3-oxatricyclo2,4>hept-6-ene and its reactions
Barlow, Michael G.,Peck, Colin J.
, p. 179 - 192 (2007/10/02)
Vapour-phase ultraviolet irradiation of hexafluorobenzene in the presence of oxygen slowly yields hexafluoro-3-oxatricyclo2,4>hept-6-ene (2) (10percent).The CF=CF bond in 2 adds (yields of adducts given) the dienes; cyclopentadiene (74percent), furan (61percent) and 2,5-diphenylisobenzofuran (59percent); benzonitrile oxide (58percent); chlorine (59percent) and bromine (71percent) photochemically.Heptene 2 isomerises thermally hexafluorocyclohexa-2,4-dienone (6) (60percent) at 50 deg C, and reacts with diethyl ether at room temperature yielding ethyl fluoride (89percent) and 2-ethoxypentafluorocyclohexa-2,5-dienone (21percent).The benzonitrile oxide adduct, upon flow pyrolysis at 440 deg C, yields an isomeric oxepin derivative and the cyclohexadienone 6 with longer contact times.The chlorine adduct similarly yields a dichloro-oxepin derivative; attempts to dechlorinate this to hexafluoro-oxepin were unsuccessful.Benzonitrile oxide adds to one or both of the C=C bonds of hexafluorobicyclohexa-2,5-diene; the 1:1 adduct isomerises thermally to the benzonitrile oxide-hexafluorobenzene adduct.
Synthesis and Chemistry of Highly Fluorinated Bicyclohexenone
Soelch, Richard R.,McNierney, Edward,Tannenbaum, Gary A.,Lemal, David M.
, p. 5502 - 5511 (2007/10/02)
A series of highly fluorinated bicyclo-5-hexen-2-ones (3) and their hydrates (4) have been prepared in two steps from hexafluoro Dewar benzene (1).Photolysis of exo-3H-pentafluorobicyclo-5-hexen-2-one (3d) at low pressure in the vapor phase gave 1H-pentafluorocyclopentadiene (8), but in solution the principal product was pentafluorophenol (9).Under Favorskii conditions, exo-3-bromo- and exo-3-chloropentafluorobicyclo-5-hexen-2-one (3a and 3b) ring opened stereospecifically to 2-cyclobutenecarboxylic acids 17 and 29, respectively.Treatment of these ketones with tert-butoxide under aprotic conditions effected stereospecific cleavage to tert-butyl methylenecyclobutenecarboxylates 25 and 30.The acid (27) corresponding to 25 was obtained both from bromohydrate 4a and the acid 17, again stereospecifically, by reaction with lithium diisopropylamide.Flash vacuum pyrolysis of the hydrate (4c) of of hexafluorobicyclo-5-hexen-2-one at 300 deg C gave hexafluoro-2,4-cyclohexadienone (12), which decarbonylated at higher temperatures to yield hexafluorocyclopentadiene (13).Similarly, flash vacuum pyrolysis of 3-chloropentafluorobicyclo-5-hexen-2-one (3b) at 650 deg C gave a mixture of 1- and 2-chloropentafluorocyclopentadienes.
New Routes to Hexafluorocyclopentadiene and Related Compounds
Soelch, Richard R.,Mauer, George W.,Lemal, David M.
, p. 5845 - 5852 (2007/10/02)
Hexafluorocyclopentadiene (1) has been synthesized in two steps from pentafluorophenol (2) by fluorination followed by flash vacuum pyrolysis of the resulting hexafluorocyclohexadienones 3 and 4.Similar pyrolysis of 6-chloropentafluorocyclohexadienone (13) gave an equilibrium mixture of 1- and 2-chloropentafluorocyclopentadiene (15 and 16), presumably via the 5-chloro isomer.Flash vacuum pyrolysis of tetrafluoro-o-benzoquinone 17 yielded tetrafluorocyclopentadienone (20).Hexafluorocyclopentadiene was also prepared via a ring-expansion route which entailed cycloaddition (accompanied by rearrangement) of bromotrifluoroethylene to tetrafluorocyclopropene followed by reductive debromofluorination.
BF3-Catalyzed Fluorine Addition to Fluoro-Substituted Benzene Derivatives Using Xenon Difluoride
Stavber, Stojan,Zupan, Marko
, p. 300 - 302 (2007/10/02)
BF3-catalyzed room-temperature reaction of xenon difluoride with pentafluoro-substituted benzene derivatives resulted in 1,4- and 1,2-fluorine addition with regiospecificity depending on the substituent.Reaction with 1-substituted (H, Cl, Br, C6F5) pentafluorobenzene resulted in the formation of 1-substituted heptafluorocyclohexa-1,4-dienes, and reactions with n-alkoxy-substituted pentafluorobenzenes resulted in two types of 1,4-adducts, while reaction with isopropoxypentafluorobenzene resulted in the formation of hexafluorocyclohexa-2,5-dien-1-one and hexafluorocyclohexa-2,4-dien-1-one.
Hexafluoro-3-oxatricyclo2,4>hept-6-ene (Hexafluoro-Dewar-benzene Oxide) from the Photochemical Oxidation of Hexafluorobenzene
Barlow, Michael G.,Haszeldine, Robert N.,Peck, Colin J.
, p. 158 - 159 (2007/10/02)
Photochemical oxidation of hexafluorobenzene in the vapour phase yields the title compound, which undergoes thermal rearrangement into hexafluorocyclohexa-2,4-dienone and two acid fluorides, attack by diethyl ether at the oxiran ring, and cycloaddition to its C=C double bond.
