Gas-Phase Oxidation of NO₂ to HNO₃ by Phenol: Atmospheric Implications

Abstract

The thermal reaction between nitrogen dioxide and phenol in the gas phase under anaerobic conditions has been investigated by diluting the reactants in dry nitrogen in a glass reaction vessel. Infrared spectroscopic analysis reveals that nitric acid, nitric oxide, and o-nitrophenol are the major products of the reaction. The kinetic analysis reveals the reaction stoichiometry as 3NO2 + PhOH → HNO3 + NO + o-nitrophenol, and the corresponding reaction enthalpy is Δr H 0 = −44.82 kcal/mol. Reaction monitoring by NO2 concentration variation shows that HNO3 formation is linearly correlated with the effective concentration of the nitrogen dioxide dimer (N2O4) formed, and the overall reaction follows a second-order kinetic behavior with respect to N2O4 and phenol, and the estimated rate constant value is (3.53 ± 0.56) × 10–18 cm3 molecule–1 s–1 at 298 K. In the presence of excess NO2, the reaction shows a pseudo-first-order kinetic behavior with a rate constant of (6.67 ± 0.12) × 10–3 s–1. The electronic structure calculation predicts that the N2O4–phenol complex can have multiple conformational minima, and in the lowest-energy conformer, the orientation of the two NO2 molecules about the phenolic −OH group is similar to that of the charge-separated asymmetric ONONO2 dimer of NO2. A radical mechanism has been ruled out, as HONO has not been identified as a product. To the best of our knowledge, the formation of o-nitrophenol in the gas-phase reaction between phenol and NO2 is reported here for the first time. The atmospheric implication of the reaction has been discussed.

NO2 Absorption in Aqueous Solutions with Phenolic Additives: Hydroquinone and 4-Methylaminophenol Sulfate

“…20 In gas-phase reactions, NO 2 may react with phenols to form HNO 3 , NO, and nitrophenols. 17 In the liquid phase, the solvent influences the reaction products. 21,22 In order to understand the reactions of NO 2 in aqueous solutions containing phenolic compounds, Ammann et al investigated hydroxy-and methoxy-substituted phenols in a wetted-wall reactor to obtain rate-constants for the NO 2 uptake under conditions relevant for atmospheric chemistry.…”

“…Besides their ability to reduce sulfite oxidation, substituted phenols can also react directly with NO 2 . The reactions between phenols and NO 2 have been of interest due to their importance in atmospheric chemistry. − Aromatic hydrocarbons represent a significant part of nonmethane hydrocarbons in the atmosphere . In gas-phase reactions, NO 2 may react with phenols to form HNO 3 , NO, and nitrophenols .…”

“…The reactions between phenols and NO 2 have been of interest due to their importance in atmospheric chemistry. − Aromatic hydrocarbons represent a significant part of nonmethane hydrocarbons in the atmosphere . In gas-phase reactions, NO 2 may react with phenols to form HNO 3 , NO, and nitrophenols . In the liquid phase, the solvent influences the reaction products. , In order to understand the reactions of NO 2 in aqueous solutions containing phenolic compounds, Ammann et al investigated hydroxy- and methoxy-substituted phenols in a wetted-wall reactor to obtain rate-constants for the NO 2 uptake under conditions relevant for atmospheric chemistry .…”

Development of a compact 406 nm diode laser-based cavity-enhanced spectrometer for high-sensitive detection of NO2 levels in exhaust gas

“…Nitrogen dioxide (NO 2 ) is an emerging pollutant in the troposphere and plays a critical role in atmospheric chemistry, contributing to tropospheric ozone layer formation, photochemical smog, and secondary aerosol production [1][2][3]. It is a highly reactive gas and has an active role in the production of nitrous acid (HONO) and nitric acid (HNO 3 ) in the atmosphere through gas-phase reactions [4][5][6]. Moreover, exposure to high * Author to whom any correspondence should be addressed.…”

A possible atmospheric source of HNO3: the ammonolysis reaction of t-N2O4 in the presence of water monomer, water dimer, and sulfuric acid

“…In the atmosphere, the hydrolysis of t-N 2 O 4 to produce HONO is the most major loss route of t-N 2 O 4 . 10,11 As a complement to the loss of t-N 2 O 4 , the ammonolysis reaction of t-N 2 O 4 can form HNO 3 , 13 which could be competitive with the main source of HNO 3 , the gas-phase reaction of NO 2 with the hydroxyl (OH) radical 8,14 during the day and the hydrolysis reaction of N 2 O 5 [15][16][17] at night, in polluted areas of NH 3 . The ammonolysis of t-N 2 O 4 (shown in eqn ( 1) and ( 2)) investigated by Lin et al 13 reveals that the energy barrier of the t-N 2 O 4 + NH 3 reaction was determined to be 5.3 kcal mol −1 and the corresponding rate constant at low temperature was not pressure-dependent.…”