Gas-Phase Proton Affinities for H2O, C2H4 and C2H6

Article abstract of DOI:10.1021/ja00399a006

Rate and equilibrium constant measurements are reported which provide proton affinities for H2O, C2H4, and C2H6 and heats of formation for the corresponding protonated species at 298 K, on the basis of the well-established proton affinity of CO.The values recommended for the proton affinities are 165.3 +/- 1.8, 163.0 +/- 1.7, and 142.1 +/-1.2 kcal mol^-1 for H2O, C2H4, and C2H6, respectively.The proton affinity obtained for H2O is lower than accepted values.The results obtained for C2H4 agree almost exactly with those obtained in a very recent photoionization (PIPECO) study by Baer.The measurements with C2H6 provide a new accurate determination of its proton affinity.