Reactions of H3O+ with a number of bromine containing fully and partially halogenated hydrocarbons

Abstract The thermal bimolecular rate coefficients and product ion branching ratios for the reactions of H 3 O + with the bromine containing molecules CH 3 Br, CH 2 Br 2 , CH 2 FBr, CHF 2 Br, CHFBr 2 , CH 2 BrCl, CHBrCl 2 , CHBr 2 Cl, CH 3 CH 2 Br, CH 2 BrCH 2 Cl, CH 2 BrCH 2 Br, CF 3 CF 2 Br and CF 2 BrCF 2 Br at 300 K are reported. H 3 O + reacts with an experimental rate coefficient ( k exp ) close to the collisional value ( k c ≈10 −9  cm 3  molecule −1  s −1 ) with CHFBr 2 , CHBrCl 2 , CHBr 2 Cl, CH 2 BrCH 2 Cl, and CH 2 BrCH 2 Br, at a decreased efficiency with CH 3 CH 2 Br ( k exp / k c ≈0.3). The other neutral reactant molecules, CH 3 Br, CH 2 FBr, CHF 2 Br, CF 3 CF 2 Br, and CF 2 BrCF 2 Br react through a three-body associative process. There is no observable reaction with CH 2 Br 2 and CH 2 BrCl. Mechanistic arguments are given that go some way to explaining the observed range in both reactivity and reaction pathways.