On the Proton Affinity of Water

Abstract

Ion–molecule reactions of proton transfer from H₃O⁺ and to H₂O were studied with several mixtures in a Bendix TOF mass spectrometer at pressures of 0.05–0.10 torr and in a CEC 21‐110B mass spectrometer at pressures as high as 0.25 torr. Proton transfer was observed from H₃O⁺ to C₃H₆, cis‐2‐C₄H₈, and CH₂O; proton transfer was observed to H₂O only from C₂H₅⁺, and not s‐C₃H₇⁺ or s‐C₄H₉⁺. These observations support the value of P.A. (H₂O) = 164 ± 4 kcal/mole.