Chemistry and spectroscopy in strongly acidic solutions. Part III: Formation of two different entities on protonation of formic acid

It has been shown by NMR spectroscopy that protonation of formic acid in HF‐BF3 solution leads to an equilibrium mixture of two different proton adducts, which probably differ in the configuration around the partly double carbon‐oxygen bond. Diffusion‐controlled proton transfer reactions take place between the stable protonated species (which are not directly interconvertible under the experimental conditions) and fluoride anions. No evidence has been found of the occurrence of protonated CO.