SCALE OF ACIDITIES IN THE GAS-PHASE FROM METHANOL TO PHENOL

The relative gas-phase acidities of 81 oxygen, nitrogen, carbon, sulfur, and phosphorus acids have been measured at 320 K with a pulsed ion cyclotron resonance spectrometer. Equilibrium constants for reactions of the general type A- + BH = B- + AH are used to determine the relative acidities of the two acids AH and BH in the absence of solvation. The experimental data are also used to calculate gaseous heats of formation for a wide variety of anions, ΔH°f(A-), electron affinities of radicals, EA (A.), and bond dissociation energies, DH°(A-H). Criteria for the establishment of equilibrium in pulsed ICR experiments are discussed. © 1979, American Chemical Society. All rights reserved.