Kinetics of the Fully Inhibited Thermal Decomposition of Bistrifluoromethyl Peroxide, CF₃OOCF₃

Abstract

BERNARD DESCAMPS and WENDELL FORST. Can. J. Chem. 53,1442(1975). The pyrolyosis of CF300CF3 (BTMP) was studied in the gas phase from 5 to 100 Torr BTMP pressure and between 197 and 244 O C in a clean nickel reactor by the static method. C F 3 0 [1 I radicals, due to the initial split CF300CF3 + 2CF30, were scavenged by S 0 3 F radicals produced in situ by the thermal decomposition of their dimer S206F2. Under these conditions, C F 3 0 0 S 0 2 F is the only product of BTMP pyrolysis, as shown by gas chromatographic analysis. Thus the BTMP pyrolysis becomes fully inhibited and the rate of accumulation of C F 3 0 0 S 0 2 F is a measure of kl. The rate constant kl turns out to be pressure-insensitive under the experimental conditions, from which it is inferred that k1 is actually klw. the limiting high-pressure unimolecular rate constant for reaction 1. Its temperature dependence yields the result klw (s-l) = 1015.9f0. L'expression experimentale pour klw est ensuite utilisee pour la reconstitution de la courbe de la chute de k1 avec la pression, suivant la prockdure de Forst. Ce calcul confirme que k1 ne chute qu'au dessous de 10 Torr.

Bond Dissociation Energy of Peroxides Revisited

“…Trifluoromethoxy radical and di­(trifluoromethyl) peroxide are relevant to the degradation of hydrofluorocarbons in the troposphere. Early measurements yielded O–O BDE values ranging from 40 to 50 kcal/mol. − A more recent pyrolysis study determined a BDE of 47.5 kcal/mol. A computational study obtained an O–O dissociation energy of 50.0 kcal/mol at the CBS-QB3 level of theory .…”

Infrared photochemistry of bis(trifluoromethyl) peroxide

“…The thermal unimolecular decomposition of bis(trifluoromethy1) peroxide (BTMP) has been studied by Kennedy and Levy [6] and by Descamps and Forst [7,8]. The generally accepted mechanism is initial homolytic cleavage at the 0-0 bond,…”

“…The thermal unimolecular decomposition of bis(trifluoromethy1) peroxide (BTMP) has been studied by Kennedy and Levy [6] and by Descamps and Forst [7,8]. The generally accepted mechanism is initial homolytic cleavage at the 0-0 bond, ki (1) CF3OOCF3 + 2CF30 followed by decomposition of the CF30 radical, (6) are supposed to occur at nearly gas-kinetic rates, without activation energy; estimates for the propagation rate coefficients are k4 N exp(-20,000/RT) and 125 N An alternative decomposition mechanism has been suggested by Christe and Pilipovich [9], on the basis of pyrolysis + matrix-isolation studies.…”