Reactions of NO<sub>3</sub> with aromatic aldehydes: gas-phase kinetics and insights into the mechanism of the reaction

Abstract

Abstract. Rate coefficients for the reaction of NO3 radicals with a series of aromatic aldehydes were measured in a 7300 L simulation chamber at ambient temperature and pressure by relative and absolute methods. The rate coefficients for benzaldehyde (BA), ortho-tolualdehyde (O-TA), meta-tolualdehyde (M-TA), para-tolualdehyde (P-TA), 2,4-dimethyl benzaldehyde (2,4-DMBA), 2,5-dimethyl benzaldehyde (2,5-DMBA) and 3,5-dimethyl benzaldehyde (3,5-DMBA) were k1= 2.6 ± 0.3, k2= 8.7 ± 0.8, k3= 4.9 ± 0.5, k4= 4.9 ± 0.4, k5= 15.1 ± 1.3, k6= 12.8 ± 1.2 and k7= 6.2 ± 0.6, respectively, in the units of 10−15 cm3 molec.−1 s−1 at 298 ± 2 K. The rate coefficient k13 for the reaction of the NO3 radical with deuterated benzaldehyde (benzaldehyde-d1) was found to be half that of k1. The end product of the reaction in an excess of NO2 was measured to be C6H5C(O)O2NO2. Theoretical calculations of aldehydic bond energies and reaction pathways indicate that the NO3 radical reacts primarily with aromatic aldehydes through the abstraction of an aldehydic hydrogen atom. The atmospheric implications of the measured rate coefficients are briefly discussed.

Oxidation of Catechols at the Air–Water Interface by Nitrate Radicals

“…The effective concentration of NO 3 to which the surface of microdroplets was exposed is obtained by integrating P NO 3 over the residence time t r = 8.77 s; the mixture of O 3 (g) and NO 2 (g) is in the quartz cuvette before its transfer to the final PTFE line directing the flow to impinge the microdroplets. In addition, the wall loss of NO 3 , normalN normalO 3 → walls taking place inside the quartz ( k R3 ≃ 0.11 s –1 ) , cuvette and the PTFE ( k R3 = 7.1 × 10 –3 s –1 ) transfer line, , indicates that a cumulative transmission efficiency of 3.0% of the produced NO 3 reaches the microdroplets’ surface. Only dry gases are used in the generation and dilution of oxidizer mixtures, which impinge the microdroplet generated at a fixed pH.…”

“…taking place inside the quartz (k R3 ≃ 0.11 s −1 ) 42,43 cuvette and the PTFE (k R3 = 7.1 × 10 −3 s −1 ) 44 transfer line, 42,45 indicates that a cumulative transmission efficiency of 3.0% of the produced NO 3 reaches the microdroplets' surface. Only dry gases are used in the generation and dilution of oxidizer mixtures, which impinge the microdroplet generated at a fixed pH.…”

Mechanism, thermochemistry, and kinetics of the reversible reactions: C2H3 + H2 ⇌ C2H4 + H ⇌ C2H5

“…1.124 is a successor to ver. 1.122× that was used in a recent study of the C–H bond dissociation enthalpies (BDE) of aromatic aldehydes, 24 itself being a result of successive expansions of earlier versions, such as 1.122h, 25 1.122o, 26 1.122p, 27 1.122q, 28,29 1.122r, 30 and 1.122v. 31…”

Emission Characteristics and Formation Mechanism of Carbonyl Compounds from Residential Solid Fuel Combustion Based on Real-World Measurements and Tube-Furnace Experiments

“…− leads to the rapid production of a large number of secondary pollutants. 22,25,26 Due to the strong atmospheric activity, the life of CCs in the atmosphere is relatively short, for example, the life of formaldehyde and acetaldehyde in the atmosphere is about 8 and 6.4 h. 25,27 could pose a threat to human health; long-term exposure to high concentrations of CCs can cause respiratory diseases and increase nephrotoxicity, as well as the risk of cancer. 28−30 Unsaturated aldehyde has strong mutagenicity; 31 acrolein and crotonaldehyde are listed as "probably carcinogenic to human group" by International Agency for Research on Cancer (IARC).…”

“…The concentration of CCs in ambient air can reach 57 ± 10% of VOCs in large cities . CCs have attracted attention because of their strong atmospheric chemical reactivity; CCs are important precursors of secondary organic aerosols − and can significantly enhance atmospheric oxidation, , wherein the reaction with OH radicals and NO 3 – leads to the rapid production of a large number of secondary pollutants. ,, Due to the strong atmospheric activity, the life of CCs in the atmosphere is relatively short, for example, the life of formaldehyde and acetaldehyde in the atmosphere is about 8 and 6.4 h. , Simultaneously, CC could pose a threat to human health; long-term exposure to high concentrations of CCs can cause respiratory diseases and increase nephrotoxicity, as well as the risk of cancer. − Unsaturated aldehyde has strong mutagenicity; acrolein and crotonaldehyde are listed as “probably carcinogenic to human group” by International Agency for Research on Cancer (IARC) . Thus, the control of CC emissions will be beneficial for both air pollution control and human health. , …”