Solvent effects on intermolecular proton transfer: the rates of nitrene protonation and their correlation with Swain acity.

The rate of protonation of singlet 2-fluorenylnitrene was studied in eight protic solvents. The protonation rates vary between 10(11) and 10(9) s(-1) and are well-correlated with Swain's acity parameters. This demonstrates that Swain acity parameters and nitrene protonation rates can be used to evaluate bulk solvent acidity.