Reactions of C3H6+ with C3 and C4 Paraffins

Abstract

Rate constants for H⁻ and H₂⁻ transfer from C₃ and C₄ paraffins to propylene and cyclopropane molecular ions have been determined for ions of low translational energy at the ionization threshold of C₃H₆⁺. The results indicate that an increase in K_H⁻ is accompanied by a compensating decrease in KH₂⁻ and vice versa, such that the total reactivity of C₄ structural isomers is invariant. By using selectively labeled compounds, it was possible to derive transfer probabilities for the various substituent sites on the normal butane carbon skeleton. Evidence is also presented which suggests that cyclopropane molecular ions do not assume the propylene‐ion structure prior to or during reaction with C₄ paraffins. The results of the present investigation are compared with some complementary data obtained from radiolytic and photolytic systems at much higher pressures.