Influence of Protonation Exothermicity on Gas-Phase Concurrent Dealkylation and Isomerization of p-Cymene

Abstract

The gas-phase protonation is reported of p-cymene (p- isopropyltoluene ) by different radiolytically formed protonating agents (O₂H⁺, N₂H⁺, CH₅⁺, COH⁺). The characteristics of the reactions vary with the protonation exothermicity . Both dealkylation and isomerization are observed with O₂H⁺ or N₂H⁺ ions. Only dealkylation occurs when the protonating agent is the CH₅⁺ ion. Formation of products is not observed when the less energetic COH⁺ ions are employed. The results show that in the competition between isomerization and dealkylation the dealkylation reaction becomes favoured as the protonation exothermicity decreases.