Mechanistic and kinetic aspects of the reduction of nitryl chloride in aprotic media

In order to bring more information on the thermodynamic and kinetic behavior of nitryl chloride in aprotic media, we have surveyed exhaustively the first NO₂Cl-reduction step in sulfolane (at the platinum electrode), taking into account our preliminary results about the electrochemical properties of NO₂Cl in aprotic solvents. We have excluded the intervention of the weak ionic dissociation of NO₂Cl (NO₂Cl ⇆ NO + Cl⁻ [I]) and its slow molecular decomposition as: 2NO₂Cl ⇄ Cl₂ + 2NO (⇄ N₂O₄) [II] in this process. We have admitted the occurrence of a rapid chemical reaction which controls kinetically the electrochemical system studied: \documentclass{article}\pagestyle{empty}\begin{document}$ {\rm NO} + {\rm NO}_{\rm 2} {\rm Cl}\buildrel {k^*} \over \longrightarrow {\rm NOCl} + {\rm NO}_{\rm 2}^ \cdot {\rm}[{\rm III]} $\end{document}. By analyzing the kinetic currents resulting from the 1 st cathodic wave of NO₂Cl at the temperature range 303–323 K, the rate constant, k*, and the activation energy, E*, of reaction [III] have been determined. These results and those previously found in the gas phase are discussed.