Homolytic reactions of polyfluoroaromatic compounds V. The reaction of pentafluorophenyl radicals with fluorobenzene

The arylation of fluorobenzene with pentafluorophenyl radicals obtained by the reaction of the corresponding aniline with pentyl nitrite is described. The reaction involves attact at the 2t?-,3t?-and 4t?-positions. The composition of the mixture and the nature of its components were determined by ¹⁹F NMR spectroscopy and were confirmed by gas-liquid chromatography.     

A diatropic ring current in a fluorofullerene trannulene

Ipsocentric current-density maps for a fluorofullerene derivative, C60F15H3, modelling the addition pattern of the experimentally characterised C60F15[CBr(CO2Et)2]3 which contains an [18]trans-annulene system, reveal a diamagnetic ring current dominated by the contribution of the four HOMO electrons, as in a classical (4n + 2) aromatic annulene.     

Homolytic reactions of polyfluoroaromatic compounds. X. Biphenylyl radicals in the thermolysis of aroyl peroxides in polyfluoroaromatic solvents

The thermolyses of a number of aroyl peroxides in hexafluorobenzene, and of benzoyl peroxide in octafluorotoluene, gave the corresponding biaryls which were isolated by steam distillation. Mass spectrometry of the residues showed evidence of biphenylyl radicals arising from the arylation of the peroxides themselves or, possibly, of the derived aroic acids. Terphenyls, and the corresponding σ-intermediate radicals, could be found, and the relative molecular masses of the latter components showed that subsequent arylation of the main binuclear products was not the main source of terphenyls.     

Homolytic reactions of polyfluoroaromatic compounds. Part XII. Aryldehydrogenation and aryldefluorination in polyfluorobenzenes

The thermal decomposition of benzoyl peroxide in a range of polyfluorobenzenes at 80° gives biaryls arising from both the displacement of fluorine and hydrogen. Phenyldefluorination predominated only in the attack of 1,2,3,4-tetrafluorobenzene and of pentafluorobenzene, but was evident even in the attack of $\text{o}$-difluorobenzene. The relative rates of displacement, as shown by the isomer distributions, were generally well reflected by the application of partial rate factors found in the phenylation of fluorobenzene; however, phenyldefluorination was not so easily amenable to this treatment, a possible consequence of complex formation between radical precursor and substrate.     

Evidence from15N nuclear polarization on the mechanism of addition of nitrogen dioxide to alkenes

Nitrogen dioxide reacts with 2-ethyl-1-butene and 2-methyl-2-pentene inn-hexane as solvent to give mainly the corresponding dinitro compounds and nitro alcohols (believed to be derived from nitronitrites during the separation process). When¹⁵N-labelled nitrogen dioxide is used, the products show strong¹⁵N nuclear polarization: the signal from the first nitro group to be introduced into the alkene shows enhanced absorption and, in the dinitro compounds, the signal from the second nitro group is in emission. The results indicate that both the dinitro compounds and the nitronitrites are formed by the reaction of the alkenes with two successive nitrogen dioxide molecules. The results do not, however, exclude the possible contributions of other reaction paths.     

Nucleophilic displacement in polyhalogenoaromatic compounds. Part X. Transmission of substituent effects in polyfluorobiphenyl derivatives

The rate of methoxydefluorination (NaOMe-MeOH, 323.2 K) and the ¹⁹F-NMR chemical shifts of some substituted penta- and nona-fluorobiphenyls have been measured. The observed substituent effects parallel those found in the corresponding pentafluorobenzenes and demonstrate proportionate transmission of the total substituent electronic effect across the aromatic system.     

Nucleophilic displacement in polyhalogenoaromatic compounds. Part V. Fluorodechlorination of 1,2,3,4- and 1,2,3,5-tetrachlorobenzenes and 2,3,4,5,6-pentachlorotoluene in sulpholan

Potassium fluoride in sulpholan (tetramethylene sulphone) reacted readily with 1,2,3,4- and 1,2,3,5-tetrachlorobenzenes at 250°, but needed temperatures of 270° before fluorodechlorination of pentachlorotoluene proceeded readily. Individual rate constants for the formation and decomposition of some of the fluorochloroarenes have been isolated; their values are discussed in terms of the electronic effects of the substituents.