Electrode reactions of the methyl halides

Abstract

AbstractThe standard electrode potentials Eo and their temperature‐dependence for the half‐reactions RX + e → R + X− of the methyl halides in aqueous solution are calculated from thermodynamic data. For CH3Cl, CH3Br and CH3I, the values of Eo (25°C) are −0.77, −0.74 and −0.77 v. respectively, and dEo/dt is −0.56, −0.52 and −0.35 millivolt/°C respectively.From experimental current‐potential measurements at a dropping mercury electrode and the calculated standard potentials, the equilibrium rate constants ko for the reactions CH3X + e(Hg) → CH3 + X− have been obtaiend in 1:1 EtOH/H2O solution, with 0.1 N NEt4I as base electrolyte. The values of ko (25°C) for the three halides are 7 · 10−9, 3 · 10−5 and 1 · 10−4 cm sec−1 respectively. The nature of the activation process is discussed.