Dissociation of proton bound ketone dimers in asymmetric electric fields with differential mobility spectrometry and in uniform electric fields with linear ion mobility spectrometry.

The kinetics for the decomposition of the symmetrical proton-bound dimers of a series of 2-ketones (M) from acetone to 2-nonanone have been determined at ambient pressure by linear ion mobility spectrometry (IMS) and by differential mobility spectrometry (DMS). Decomposition, M2H(+) →MH(+) + M, in the IMS instrument, observed under thermal conditions over the temperature range 147 to 172 °C, yielded almost identical Arrhenius parameters Ea = 122 kJ mol(-1) and ln A = 38.8 for the dimers of 2-pentanone, 2-heptanone, and 2-nonanone.