Thermodynamic ionization energies and charge transfer reactions in benzene and substituted benzenes

Ionization energies of 11 substituted benzenes of CS₂ related to the ionization energy of benzene were obtained by measurements of the charge exchange equilibrium constants for C₆H₅X⁺ + C₆H₅Y ? C₆H₅Y⁺ + C₆H₅X at 450 and K. Thermodynamic ionization energies of substituted benzenes, related to that of benzene, are found to be higher by 0.5–2.0 kcal/mole than the corresponding photoionization (0—0) values. Exothermic charge transfer reactions between substituted benzenes are found to proceed with rate constants of (1.3–1.6) × 10^?9 cm³/mol s, which agree well with calculated collision rates.