Theoretical Study on the Mechanism for the Formation of Nitro Compounds in Red Oil

Abstract

The mechanisms involved in reactions between methane, n-hexane, n-butanol, cyclohexane, and nitric acid were explored by density functional theory calculations. All the calculations in gas phase and n-tributyl phosphate (TBP) solvent were performed at the B3LYP/6–311++G ∗ ∗ and CCSD(T)/6–311++G ∗ ∗ levels of theory. The results showed that TBP has an important effect on the reactions between nitric acid and alkanes or butanol. The reactions were considered as that the radicals (·NO2 and ·NO3 radicals are formed via the HNO3 decomposition under irradiation) initiate the H-atom depletion of the reactants (R), and the produced radicals in red oil combine with ·NO2 radical to form the nitro compounds spontaneously. The rate constants of reactions R + ·NO2 and R + ·NO3 differ substantially, the rate constants of the latter being much larger than those of the former. In the reactions of R + ·NO3, the transition states and products are 20 kJ/mol and 100 kJ/mol or more stable than the reactants, respectively, but the reactions of R + ·NO2 need to overcome energy barriers over 25 kJ/mol. The formations of products mainly depend on the reactions of R + ·NO3. For the same type of alkanes (either chain or cyclic ones), the lower the relative stabilities of carbon-centered radicals are, the more reactive the alkanes are. Cyclohexane is the most competitive species, followed by n-butanol, n-alkanes, and methane which are the least competitive.

Impact of Nonthermal Plasma on Lipid Oxidation from the Perspective of Plasma Treatment Parameters and Plasma Species: Identification of Key Reactive Species

“…During plasma generation, the nitrate radical ( · NO 3 ) can also be formed and has a much larger rate constant of abstracting H-atoms compared with · NO 2 . , Although the · NO 3 concentration in air plasma was below the sensitivity of our FTIR spectrometer, its presence in air plasma has already been confirmed . Since its lifetime was recorded as seconds to minutes in atmospheric chemistry, · NO 3 is considered very likely to reach the NTP-treated samples and induce autoxidation, but its individual contribution in the NTP treatment could not be evaluated experimentally.…”