Experimental and theoretical study of the reaction system of 2NO2 ↔ N2O4 and some fluorinated derivatives of tert-butanol in the gas phase

Abstract

The reversible reaction between NO2/N2O4 and CF3C(CH3)2OH has been studied using UV–Vis spectrophotometry. The final product -CF3C(CH3)2ONO- of this reaction was identified by its UV spectrum in the wavelength range of 340–420nm. The absorption spectrum of CF3C(CH3)2ONO was recorded and the values of the absorption cross sections for prominent bands at 354.0; 367.5; 390.0nm were derived. The kinetics of the reaction has been investigated in the temperature range of 298–358K to follow the NO2 decay in a real time of the reaction. The rate constant for the forward k5 as well as for the reverse k6 reaction has been obtained and their values at 298K are: 10−19k5/cm3molecule−1s−1 1.4±0.3 and 10−19k6/cm3molecule−1s−1 15.0±4.0. From the temperature dependence of the rate constants the activation energy for the forward E5 and for the reverse E6 reaction has been calculated. It was proposed that the reaction mechanism is complex and N2O4 is the reactive species.The UV–Vis spectra have for all studied compounds been calculated. The possible reason of absence of the reaction between (CF3)3COH, CH3C(CF3)2OH and N2O4 has been proposed. All possible stable conformers of studied moieties have been obtained. Molecular Electrostatic Potential Surfaces (MEPS) of all structures have been derived.