Abstract
The radiolysis behavior of neat pyridinium ionic liquids (ILs) and their aqueous solutions was investigated using nanosecond pulse radiolysis techniques. Radiolysis of the ionic liquids, such as N-butylpyridinium tetrafluoroborate (BuPyBF4), resulted in the formation of solvated electrons and organic radicals. Solvated electrons reacted with the pyridinium moiety to produce a pyridinyl radical, which can transfer electrons to various acceptors. The electron-transfer rate constants of the solvent-derived butylpyridinyl radicals in BuPyBF4 and in several compounds (for example, duroquinone, 4,4′-pyridine, benzophenone, and 1,1′-dimethyl-4,4′-bypyridinium dichloride) (k of the order 108 L/(mol s) were lower than those measured in water and in i-PrOH but were significantly higher than the diffusion-controlled rate constants estimated based on viscosity. The electron-transfer rate constants in neat BuPyBF4 were one order of magnitude faster than the diffusion-controlled values. This finding suggests that Bu-PyBF4 acts not only as solvent but also as active solute, such as in solvent-mediated reactions. These reactions result in electrons reaching their final destinations via intervening pyridinium groups without requiring the diffusion of a specific radical.
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Fu, H., Xing, Z., Cao, X. et al. Electron transfer in N-butylpyridinium tetrafluoroborate ionic liquid by pulse radiolysis. Chin. Sci. Bull. 58, 1882–1886 (2013). https://doi.org/10.1007/s11434-013-5684-7
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DOI: https://doi.org/10.1007/s11434-013-5684-7