Ion-Molecule Reactions in Ethylene Oxide

Abstract

The ion-molecule reactions in the systems including ethylene oxide have been studied at thermal ion energies by means of the ion trapping technique using a modified time-of-flight mass spectrometer. Details of the ion source constructed in this laboratory have been described. The performance of this modified ion source has been examined by the measurement of the ion-molecule reactions in methane. The following major ion-molecule reactions have been identified to be occurring in ethylene oxide, with the measurements of the ionization efficiency curves using the RPD technique for determination of the precursors in the reactions. (All rate constants in cm3/molecule.sec.) C2H4O+C2H4O→C2H5O++C2H3O, k=1.45×10-10, CHO++C2H4O→C2H5O++CO, k=2.05×10-9, CH3++C2H4O+→C2H3O++CH4, k=2.10×10-10.By the experiments using simple hydrocarbons including ethylene-d4as the additive, the sequence of the reactivity for the protonated ion formation and the charge transfer reactions from simple hydrocarbon ions to the ethylene oxide molecule have also been studied.