REVERSIBLE-REACTION OF EXCESS ELECTRONS WITH P-DIFLUOROBENZENE IN N-HEXANE AND CYCLOHEXANE

The equilibrium reaction es- + p-C6H4F2 ⇄ p-C6H4F2-was studied as a function of temperature in n-hexane and cyclohexane solvents. The conductivity technique employed allowed measurement of both the attachment and detachment rates. The attachment rates are diffusion limited in both solvents. The detachment rates are characterized by very high preexponential factors and large activation energies. The reaction is exothermic in solution and proceeds with a large decrease in entropy. The latter can only partially be accounted for by polarization by the product anion, but in addition indicates a positive entropy of solution of the electron. A linear correlation of ΔGreac with electron affinity is presented. The results are consistent with an electron affinity of p-difluorobenzene equal to approximately -0.35 eV. © 1979 American Chemical Society.