Proton affinities of primary alkanols: An appraisal of the kinetic method

The kinetic method is a now well-established technique for determining thermochemical properties such as acidities and proton affinities. We present here a study of the application of the kinetic method to the proton affinities (PA) of a series of homologous primary alkanols, namely ethanol through n-octanol. Both metastable and collisionally activated dissociations of proton-bound alkanol pairs were studied, the latter as a function of the target gas and its pressure. Plots of ln([R1OH2+]/[R2OH2+]) VS PA for both experiments were obtained to determine new PA values and investigate the significance of the "effective temperature" term. When the experiments are considered in detail, it is apparent that the kinetic method is essentially a semiempirical relationship, without a sound physicochemical basis.