Hydrogenation of ethylene on metal electrodes. Part 3.—Isotopic exchange and deuteration reactions at a platinum electrode on open circuit

Abstract

Deuteration of ethylene and isotopic exchange of deuterium in the systems of D₂/H₂O, C₂H₄+ C₂D₄/H₂O and D₂+ C₂H₄+ C₂D₄/H₂O are studied at a platinum electrode on open circuit in 1 N HClO₄ solution. Results show that (i) ethylene undergoes molecular, irreversible adsorption, (ii) in region E where P_H/P_E > 5–6, deuterium atoms from D₂ do not appear in the product ethane, whereas in region H, P_H/P_E < 5–6, deuterium atoms appear in the product at ca. 46 %, and (iii) the deuterium atoms in ethane are distributed almost randomly. These results are discussed in terms of the relative rates of the elementary steps of the mechanism.