Studies on gas-phase positive ion-molecule reactions initiated by proton transfer to alcohols: the reactions of 2-methyl-2-propanol ( t-butyl alcohol) with H 3O + in a Fourier transform mass spectrometer (FTMS)

Abstract

An understanding of the chemistry of the ion-molecule reactions occurring in an ion mobility system is a prerequisite to fully exploiting the potential of Ion Mobility Spectrometry for the detection and monitoring of pollutants. Whilst it is commonly thought that clustering around a proton is the dominant process occurring in the positive ion mode, previous studies have shown that much more complex processes can and do occur. The present paper is the first of a series reporting fundamental investigations of the ion-molecule reactions that can be initiated by proton transfer at low pressure in a Fourier transform mass spectrometer. Preliminary studies have shown that carbonium ion formation could be the dominant process. It was therefore decided that, as a first step, the reactions of t-butyl alcohol (2-methyl-2-propanol) would be studied as the carbonium ion would, if formed, not undergo any rearrangement being already in its most stable and energetically well-characterised structure.