n-Alkane Nanoparticles in Cryogenic Trichlorofluoromethane-Alkane Systems: Their Use in the Study of the σ-Basicity of n-Alkanes

摘要

Under cryogenic conditions, n-alkane nanoparticles are formed in trichlorofluoromethane-alkane systems. γ-Irradiation in combination with EPR-spectroscopy has been utilized to characterize these nanoparticles and to determine their physical state (crystalline vs. amorphous). From such experiments, it appears that the size of these nanoparticles can be controlled through experimental parameters, such as concentration and chain length of the n-alkane solute, and that it may range from essentially monomolecular to aggregates large enough to crystallize. The n-alkane nanoparticles appear very useful for gaining insight into the properties of pentacoordinated alkyl carbonium ions and into the σ-basicity of n-alkanes. γ-Irradiated cryogenic trichlorofluoro-methane-alkane systems have proven invaluable in the study of symmetric proton transfer from alkane radical cations to alkane molecules, a reaction process that is characterized by quite intriguing selectivity with respect to both the site of proton donation and proton acceptance. Such investigations are currently leading to a profound insight into the relative propensity of different C-H bonds in alkanes to act as proton acceptor.