Thermal decomposition of trifluoromethoxycarbonyl peroxy nitrate, CF₃OC(O)O₂NO₂

Abstract

Abstract The thermal decomposition of trifluoromethoxycarbonyl peroxy nitrate, CF 3 OC(O)O 2 NO 2 , has been studied between 278 and 306 K at 270 mbar total pressure using He as a diluent gas. The pressure dependence of the reaction was also studied at 292 K between 1.2 and 270 mbar total pressure. The rate constant reaches its high‐pressure limit at 70 mbar. The first step of the decomposition leads to CF 3 OC(O)O 2 and NO 2 formation, that is, CF 3 OC(O)O 2 NO 2 + M ⇆ CF 3 OC(O)O 2 + NO 2 + M ( k 1 , k −1 ). Reaction (−1) was prevented by adding an excess of NO that reacts with the peroxy radical intermediate and leads to carbonyl fluoride (CF 2 O), carbon dioxide (CO 2 ), nitrogen dioxide (NO 2 ), and small quantities of CF 3 OC(O)O 2 C(O)OCF 3 . The kinetics of reaction (1) was determined by following the loss of CF 3 OC(O)O 2 NO 2 via IR spectroscopy. The temperature dependence of the decomposition follows the equation k 1 (T) = 1.0 × 10 16 e −((111±3)/(RT)) for the exponential term expressed in kJ mol −1 . The values obtained for the kinetic parameters such as k 1 at 298 K, the activation energy (E a ), and the preexponential factor (A) are compared with literature data for other acyl peroxy nitrates. The atmospheric thermal stability of CF 3 OC(O)O 2 NO 2 and its dependence with altitude is discussed. © 2008 Wiley Periodicals, Inc. Int J Chem Kinet 40: 831–838, 2008