Hydride and Proton Transfer Reactions Involving Sec-Propyl Ions

The reactions of sec‐propyl ions produced in the radiolysis of n‐C₄D₁₀ and i‐C₄D₁₀ with hydrocarbons has been investigated. When the additive (RH) is a saturated hydrocarbon, the hydride transfer reaction: $${\mathrm{C}}_3{\mathrm{D}}_7^{+}+\mathrm{RH}\to {\mathrm{C}}_3{\mathrm{D}}_7\mathrm{H}+{\mathrm{R}}^{+}$$ is the major mode of reaction. For straight chain hydrocarbons, the cross section of this reaction, relative to that of the reference reaction $${\mathrm{C}}_3{\mathrm{D}}_7^{+}+{\mathrm{C}}_4{\mathrm{D}}_{10}\to {\mathrm{C}}_3{\mathrm{D}}_8+{\mathrm{C}}_4{\mathrm{D}}_9^{+}$$ is shown to increase with the molecular weight of RH. For different hydrocarbon isomers, the relative cross section of the hydride transfer reaction decreases with an increase in branching while the analogous reactions involving ethyl ions show no such discrimination. From the isotopic analysis of the propanes and propylenes produced in the radiolysis of C₄D₁₀ carried out in the presence of olefins, it was concluded that the proton transfer reaction $${\mathrm{C}}_3{\mathrm{D}}_7^{+}+\mathrm{RH}\to {\mathrm{C}}_3{\mathrm{D}}_6+{\mathrm{RHD}}^{+}$$ occurs. Comparison of the data obtained, using C₃D₈, n‐C₄D₁₀, and i‐C₄D₁₀ as sources of ethyl or propyl ions, indicated that the relative cross sections of the hydride transfer reactions are independent of the origin of the carbonium ion.