Mass-spectrometric study on ion-molecule reactions of CF3+ with PhX [X=H, CH3, and C2Hn (n=1,3,5)] at near-thermal energy

The gas-phase ion-molecule reactions of CF3+ with benzene, toluene, ethylbenzene, styrene, and ethynylbenzene have been studied at near-thermal energy using an ion-beam apparatus. The major product channels are electrophilic addition followed by HF elimination for benzene (93.4+/-2.2%), toluene (84.3+/-2.4%), and ethynylbenzene (76.9+/-0.9%). The dominant product channels for ethylbenzene are electrophilic addition followed by C2H4 and C2H4+HF eliminations (78.9+/-4.7%), while those for styrene are electrophilic addition followed by one or two HF eliminations and C2H2F2 elimination (91.7+/-5.4%). Only ethynylbenzene gives an initial adduct ion with a small branching ratio of 6.2+/-0.4%. As minor product channels, hydride transfer occurs for benzene (6.6+/-2.2%) and toluene (7.8+/-1.5%), and charge transfer takes place for toluene (7.9+/-2.0%), styrene (8.3+/-1.40%), and ethynylbenzene (6.2+/-0.4%). The reaction mechanisms are discussed on the basis of product ion distributions and semi-empirical calculations of potential energies of reaction pathways.