PHYSICOCHEMICAL PROPERTIES OF CHLORINE OXIDES .1. COMPOSITION, ULTRAVIOLET-SPECTRUM, AND KINETICS OF THE THERMOLYSIS OF GASEOUS DICHLORINE HEXOXIDE

The experimental evidence presented here shows that gaseous dichlorine hexoxide at room temperatures has essentially the composition Cl2O6 and not ClO3 as currently accepted. Vapor pressure measurements of liquid Cl2O6 between 5 and 45 °C have been made. The absorption cross section values of gaseous Cl2O6 are approximately 3 times higher than those assigned to ClO3 by other authors. The products of the thermal decomposition of gaseous Cl2O6 are mainly chlorine perchlorate and oxygen. The kinetics of the decomposition over the Cl2O6 pressure range 0.5-1.2 Torr, at 20-30°C, follows a first-order rate equation and is independent of the total pressure. A unimolecular process, namely, Cl2O6 → Cl2O4 + O2, proceeding at the high-pressure limit through a complex fission reaction is postulated. The rate constant k∞ = 10(11.4±1.2) exp[(-10370 ± 800)/T] s-1 is determined. © 1990 American Chemical Society.