The gas phase reactions of the trichloromethylium ion with alkyl aromatics, studied by high pressure mass spectrometry

Abstract

The reactions of trichloromethylium (CCl3+) with benzene and the lower alkyl aromatics (ArH) have been studied by high pressure mass spectrometry at pressures in the range 2–4 Torr and temperatures from 300 to 560 K. The only two primary products are the adduct ArHCCl3+ and ArCCl2+, which is formed by loss of HCl from the adduct. The relative yields of adduct increase with increasing number of methyl substituents on the aromatic ring (benzene → mesitylene). The disappearance of CCl3+ is kinetically second order with specific rate constants increasing from benzene to mesitylene, the latter reacting essentially at every ion–molecule collision. All rate constants are fairly large (>1010 cc molecule−1 s−1) and show negative temperature coefficients. ArCCl2+ is unreactive but ArHCCl3+ reacts further by proton transfer to ArH.

The reactions of trichloromethylium with oxygen- and sulfur-containing compounds

“…In earlier experiments with CC13+ using high pressure mass spectrometry (HPMS) with ion source pressures in the range 2-5 Torr, we found that stable aromatic.CC13' adducts were observable (2) whereas previous studies at much lower ion source pressures (-Torr) had failed to detect such species (3,4). Thus while collisional stabilization is not of importance at low pressures, it can be of significance at the higher pressures of our HPMS studies.…”

“…Results and discussion CC13+ is formed from CC14 by dissociative proton transfer from CH5+ and C2H5+, the major reagent ions in methane (2).…”