Homolytic Reactive Mass Spectrometry of Fullerenes: Peculiarities of the Reactions of C60 with Aromatic Compounds in the Ionization Chambers of Mass Spectrometers and in Solution

C₆₀ reacted with PhH, PhCl, BnH, BnNH₂, and o-C₂H₂B₁₀H₁₀ in the electron impact (EI) ion source of a mass spectrometer at 300 °C forming phenyl, benzyl, and o-carboranyl adducts, respectively, stabilized by hydrogen addition and loss. Besides, the additions to C₆₀ of methyl and phenyl radicals for toluene, and a phenyl radical for benzylamine were observed. A homolytic reaction mechanism was suggested involving the reaction of the radicals formed from the aromatics under EI with C₆₀ at the ionization chamber walls. While the ion/molecule reaction of C₆₀ with benzene performed by Sun et al. under chemical ionization conditions at 200 °C afforded the complex C₆₀?PhH^+?, quite a different isomer, HC₆₀Ph^+?, was detected in the present study as a sequence of the different reaction mechanisms. C₆₀ also reacted with benzyl bromide in the laser desorption/ionization (LDI) source of a mass spectrometer to give C₆₀CPh⁺. Phenyl and benzyl derivatives of C₆₀ were found, respectively, when the reactions of the fullerene with PhCl, BnH, and BnBr were performed in solution under ultra violet irradiation. For the reaction with toluene, the strong chemically induced dynamic electron polarization of the intermediate benzylfullerenyl radical with the reverse phase effect was found. The coincidence of the results of the mass spectrometry and solution reactions of C₆₀ with aromatics, even though incomplete, additionally supports the hypothesis, formulated earlier, that the former results can predict the latter ones to a significant extent and shows that this conclusion is valid for both EI and LDI initiated reactions in mass spectrometers.      

Reactivity of esters of 2-cyanoacrylic acid toward some free radicals

The rate constants for the addition of ^·CH(Ph)CH₂CCl₃, ^·CH₂Ph, ^·CH₂Prⁿ, and ^·CCl₃ radicals to the ethyl 2-cyanoacrylate molecule were determined by ESR spectroscopy using the spin trapping technique.     

Stable fluoroaliphatic radicals containing functional groups: Synthesis and reactivity

β-Fluorosulphatoperfluoroalkyl radicals (3, 7 and 8) are obtained by the reaction of fluoroolefins (HFP trimer and dimer, and perfluoro4 4-dimethylpent-2-ene, respectively) with (FSO₃)₂. The pure β-fluorosulphatotetrafluoroethylperfluorodiisopropylmethyl radical (3) has been isolated and converted to the perfluoroacetyldiisopropylmethyl radical (4) under the action of CsF. The reaction of radicals 3,7 and 8 with SbF₅ leads to the replacement of the FSO₃ group by a fluorine atom. The ability of the FSO₃ group in β-fluorosulphatoperfluoroalkyl radicals to play the role of a leaving group is explained by the stabilizing effect of the unshared electron on the adjacent carbocation centre.     

Stable radicals — The intermediates in the photochemical chlorination of unsaturated perfluoro compounds

We have studied the photochemical chlorination of perfluorinated alkenes, 1,2- and 1,3-dienes, and a cross-conjugated triene. By means of EPR we have recorded the stable intermediates, viz., alkyl and allyl radicals that can split off a chlorine atom. In every case formation of the allyl radical is regiospecific; the sterically least-strained structure is obtained.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 5, pp. 1223–1227, May, 1991.     

Reaction of phosphonyl radicals with substituted orthobenzoquinones

Conclusions The reaction of a diethylphosphonyl radical with substituted orthobenzoquinones proceeds in two directions: addition to an oxygen atom, to form a phenoxyl-type radical, or to the ring, to form a cyclohexadienyl-type radical.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 11, pp. 2563–2569, November, 1987.     

Radical Polymerization of the Silene (Me3Si)2SiCR2 by Hydrogen Transfer from a Trimethylsilyl Group

The silene (Me₃Si)₂Si?Ad is polymerized to produce a polycarbosilane with an unusual Si? Si? C repeating backbone, rather than the Si? C or Si? Si? C? C units expected for olefinic radical polymerization. The polymer structure and the polymerization mechanism (see scheme) were studied by GPC, EPR, and NMR spectroscopy and by trapping experiments.