Reactions of propene and cyclopropane radical cations with neutral ethylene

The gas‐phase reactions of propene and cyclopropane radical cations with neutral ethylene were investigated by using Fourier transform, chemical ionization and tandem mass spectrometries. Both reactions form covalent C₅H₁₀ adduct ions. The adduct ions are hypothesized to form initially as distonic radical cations that isomerize via a substituted cyclopropane intermediate and are detected as the most stable C₅H₁₀ isomer, the 2‐methylbut‐2‐ene radical cation. The rate constant for each reaction is approximately 20% of the theoretical collision rate, indicating that product ions are formed in one out of every five collisions of the C₃H₆ radical cations with neutral C₂H₄.