Fluorocarbons, Fluorohydrocarbons, and Polyfluorohalogeno-compounds

Although a number of 1 1 cycloadducts are formed in the photochemical reaction between hexafluorobenzene and cyclo-octene, irradiation of a mixture of the arene and 2,3-dimethylbut-2-ene yields mainly the open-chain adduct CjFj-CMea CMeaF. The reaction is unaffected by the presence of proton-donors and possibly involves formation and rearrangement of the biradical (27). In a related reaction, l,3,4,S,6-pentafluorobenzocyclobutene 

An unusual Friedel-Crafts reaction occurs between pentafluorobenzene and hexafluoropropene in the presence of antimony pentafluoride cis- and rranj-perfluoro(propenylbenzene), C,F6 CF CF CF3, and /rons-perfluoro-(1,3-diphenylpropene), CeF5-CF CF CF, C,Fs, are formed, probably via the carbocations (CF2i CFiiiCF, + and (C,Fs-CF CF--iiCF3)+. The reaction between pentafluorobenzene and 1,1,2-trichlorotrifluoro-ethane, also catalysed by antimony pentafluoride, proceeds with concomitant fluorination, and yields j3-chloroperfluoroethylbenzene, CjFj-CFj-CFjCl, and perfluorobibenzy .  

6-Pentafluorotoluene undergoes conventional nucleophilic displacement at the 4-position when it is treated with 9-phenylfluoren-9-yl-, 9-ethylfluoren-9-yl-, triphenylmethyl-, and phenylxanthenyl-potassium, but treatment with radical-anion reagents (potassium naphthalide or potassium biphenylide) gives low yields of 4,4 -dimethyloctafluorobiphenyl. One-electron 

The reaction of trispentailuorophenylmethane with sodium or lithium hydride under an argon atmosphere in hexamethylphosphoramide at 20— 25 °C gives a solution of the trispentafluorophenyl carbanion [(C F, C ] (c/ p. 392), the n.m.r. spectrum of which has been described. It seems probable that bispentafluorophenyl carbanions are involved in the formation of 1,1,2,2-tetrakispentafluorophenylethane from bispentafluorophenylmethyl bromide and cyanide ion, triphenylphosphine, or butyl-lithium, and their failure to carbonate during the last reaction at - 70 °C has been attributed to their relatively high stability.  

I CeF6)(CFgC02 ) (CF3COj)jI CeFB the extent to which iodine is tercovalent in these compounds is uncertain], which reacts with toluene (mainly at the p-position) or benzene to give the corresponding aryKpenta- 

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