Electrochemical Investigations of the Fries Rearrangement in Ionic Liquids

摘要

The Fries rearrangement of phenyl benzoate has been studied in the AlCl_3 : 1 -butyl- 1-methylpyrrolidinium chloride buffered neutral ionic liquid, giving results similar to those found in the analogous 1-ethyl-3-methylimidazolium chloride system. In the former system, it is possible to observe the reduction of sodium ion, allowing assessment of the buffer level in the system. Further work involves the Fries rearrangement of phenyl benzoate in 1-butyl-1-methylpyrrolidinium triflate ionic liquid. In contrast to the l-ethyl-3-methylimidazolium tetrafluoroborate system, addition of Lewis acids such as aluminum chloride and boron trifiuoride does not result in extensive complexation of the ester in 1-butyl-1-methylpyrrolidinium triflate. An enhancement of the ester reduction processs is, however, observed, indicating that the added acids can interact with the ester to produce an ECE process. These results suggest that the Lewis acids form adducts with the triflate anion, preventing the full activity toward the ester.