Supercritical Carbon Dioxide: A Promoter of Carbon-Halogen Bond Heterolysis

Amazing reaction medium: Supercritical carbon dioxide, with zero dipole moment, lower dielectric constant than pentane, and non‐hydrogen‐bonding behavior, ionizes carbon–halogen bonds, dissociates the resulting ion pairs, and escapes from capture by the carbocation intermediates at temperatures above 40 °C. These properties allow the observation of carbocation chemistry in the absence of acids.