Kinetic Mass Spectrometric Investigation of the Reactions of Ions With Some Simple Polar Molecules at Thermal Energies.

The interactions of ions from neopentane with some simple polar molecules have been investigated in a high pressure photoionization mass spectrometer at thermal kinetic energies. Proton transfer was found to occur from to acetone, ammonia, and the various methylamines, but not to molecules having estimated proton affinities < 195 kcal/mol (815 kJ/mol). Macroscopic thermal rate coefficients are reported for the various proton transfer reactions, all of which are on the order of 10 cm/molecule · second. The reaction was found to occur, but not the analogous reaction with HO. On the basis of supplementary experiments, new limits are reported for the proton affinity of acetone. These are 203±2 kcal/mol < proton affinity of acetone < 207 kcal/mol.