Electrogenerated BF3 From Tetrafluoroborate-Based Ionic Liquids: Theoretical And Experimental Studies Towards Selective Styrene Oxide Isomerization

The anodic oxidation of tetrafluoroborate anion yields the Lewis acid BF3. If this reaction is carried out in an imidazolium ionic liquid, a quite stable system containing BF3 is obtained, whose reactivity is similar to the one of BF3 center dot Et2O, but less harmful. The two reagents' stabilities were compared by computational analysis, strongly suggesting a higher stability for BF3/BMIm-BF4 system. The effect of substituents on the imidazolium ring and of the electrochemical configuration on BF3 reactivity were studied in a model reaction, styrene oxide isomerization. The experimental conditions were defined for the selective formation of phenylacetaldehyde or of 2-benzyl-4-phenyl-1,3-dioxolane. Moreover, the formation of N-heterocyclic carbene-BF3 adduct was confirmed when carrying out the electrolysis in an undivided cell. Electrogenerated BF3/BMIm-BF4 system demonstrated to be a valid alternative to commercial BF3 center dot Et2O.

Automated summary

The anodic oxidation of tetrafluoroborate anion produces the Lewis acid BF3, which yields a stable system when carried out in an imidazolium ionic liquid. Computational analysis suggests a higher stability for the BF3/BMIm-BF4 system compared to BF3·Et2O. Studies on the effects of substituents on the imidazolium ring and the electrochemical configuration on BF3 reactivity were conducted in a model reaction involving styrene oxide isomerization.