The Kinetic Acidity of Oligofluorobenzenes Correlated with Their Gas Phase Deprotonation Energies

The relative reactivities of fluorobenzene, all di-, tri-, and tetrafluorobenzenes and pentafluorobenzene toward sec-butyllithium have been assessed in tetrahydrofuran at -100 degrees C. At this temperature no subsequent transmetalation reactions take place but those compromise the outcome of the competition experiments if the latter are conducted at -75 degrees C. The rates determined at -100 degrees C reflect the basicity differences between the naked (oligo)fluorophenyl anions to the extent of 10 %.