Thermal decomposition of dialkyl peroxides and heats of formation of the ethoxyl and isopropoxyl radicals

Abstract

The gas-phase thermal decompositions of diethyl peroxide and di-isopropyl peroxide have been studied in the temperature range 134–185°C using a continuous mass-spectrometric sampling technique. Values of 10^16.1±0.7(sec^–1) and 37.3±1.2 (kcal mole^–1) and 10^15.4±0.4(sec^–1) and 37.1±0.8 (kcal mole^–1) respectively have been obtained for the Arrhenius parameters of the decomposition reactions: C₂H₅OOC₂H₅→2C₂H₅O (CH₃)₂CHOOCH(CH₃)₂→2(CH₃)₂CHO Using these parameters, revised values of –4.4±1.1 and –12.3±2 kcal mole ^–1 have been derived for the heats of formation of the ethoxyl and of the isopropoxyl radicals. Values of ca. 10^12.5 mole^–1 cm³ sec^–1 have been estimated for the rate of dimerization of ethoxyl and isopropoxyl radicals.