Measurement of the proton affinities of some methyl substituted pyrimidines via the kinetic method on a pentaquadrupole mass spectrometer

The proton affinities of 4,6-dimethyl-pyrimidine and 4-methyl-pyrimidine ha ve been measured using the kinetic method on a pentaquadrupole mass spectro meter. The experimental affinities are compared with those calculated by ab initio molecular orbital methods. Some unexpected results obtained during this work have been attributed to the formation of the 6-methyl-pyrimidin-4 -yl radical and its proton affinity has also been estimated by both theory and experiment. (Int J Mass Spectrom 194 (2000) 133-143) (C) 2000 Elsevier Science B.V.