Catalytic Reduction of α,ω-Dihaloalkanes, X(CH₂)_mX (X = Cl, Br, or I and m = 2−8), by Electrochemically Generated C₇₀^n- (n = 2 or 3) in Benzonitrile Solutions

The first report on the homogeneous electrocatalytic reduction of halogenated alkanes by C70 anions is presented. Cyclic voltammetry (CV) measurements indicate that C70n- (n = 2 or 3), electrochemically generated in 0.1 M (TBA)PF6, benzonitrile, catalyzes the dehalogenation of α,ω-dihaloalkanes, X(CH2)mX (X = Cl, Br, or I and m = 2−8). Values of the second-order rate constant, k, for the electrocatalytic dehalogenation of the α,ω-dihaloalkanes by the C70n- anions were determined by using the rotating-disk electrode (RDE) voltammetry under pseudo-first-order conditions with respect to the α,ω-dihaloalkanes. In accordance with Saveant's theory of dissociative reduction, the k values increase in the order Cl < Br < I for the investigated 1,2-dihaloethanes. The k values also decrease with the number of carbon atoms of the alkyl chain for the investigated series of α,ω-diiodoalkanes. The calculated k values for the C70n- (n = 2 or 3) catalysts are generally smaller than those for the C60n- (n = 2 or 3) catalys...