Effects of a Carboxyl Group on the Products, Mechanism, and Kinetics of the OH Radical-Initiated Oxidation of 3-Butenoic Acid Under Low NOx Conditions DOI
Anna C. Ziola, Paul J. Ziemann

The Journal of Physical Chemistry A, Journal Year: 2025, Volume and Issue: unknown

Published: Feb. 4, 2025

Concentrations of nitrogen oxides (NOx) in the U.S. have decreased so much last few decades that oxidation volatile organic compounds (VOCs), which plays a critical role formation ozone and fine particles, now often occurs urban areas under conditions are historically associated with remote rural locations. As result, alkylperoxy radicals (RO2•), key intermediates VOC oxidation, can react NO, HO2, RO2• radicals, isomerize. In this study, we primarily investigated products, mechanism, kinetics OH radical-initiated 3-butenoic acid where dominant products similar reaction 1-pentene were hydroxy-hydroperoxides formed through + HO2 reactions. 3-Butenoic has some structural properties made it ideally suited for was conducted an environmental chamber using iodide chemical ionization mass spectrometry authentic standards. The major oxo-propanoic acid, hydroxyoxo-butanoic dihydroxy-butanoic dihydroxy-dicarboxybutyl-peroxide (a ROOR dimer) measured molar yields 0.74, 0.09, 0.08, 0.03 total yield 0.94 effectively achieved mole balance. Unlike reaction, radical led almost solely to formaldehyde apparently due hydrogen bonding involving carboxyl group ROO–OOH intermediate complex. Similar ROO–OOR complex likely responsible peroxide dimer exceptional speed reactions, competitive reactions calculated from measurements modeling occur rate constant ≥3 × 10–11 cm3 molecule–1 s–1 may approach collision limit value about 5 10–10 s–1. results study demonstrate functional groups dramatic effects on atmospheric chemistry VOCs.

Language: Английский

Multigeneration Chemistry in Secondary Organic Aerosol Formation from Nitrate Radical Oxidation of Isoprene DOI Creative Commons
Toby Xu, Masayuki Takeuchi, Jean C. Rivera‐Rios

et al.

ACS Earth and Space Chemistry, Journal Year: 2025, Volume and Issue: unknown

Published: Jan. 26, 2025

The nitrate radical (NO3) oxidation of isoprene is an important contributor to secondary organic aerosol (SOA). Isoprene has two double bonds which allow for multigeneration occur. effects chemistry on the gas- and particle-phase product distributions + NO3 system are not fully understood. In this study, we conduct chamber experiments by varying ratio N2O5 (precursor NO3) concentration from 1:1 14:1 investigate formation products in both phases under different levels. Multigeneration leads gas-phase then partition into particle phase depending volatility; first-generation (15–36% total SOA) such as C5H9NO5 C10H16N2O9 have volatility (log10C* = 1.0–3.0 using partitioning method log10C* 2.6–4.5 formula method) 1–5 orders magnitude higher than second-generation (37–57% SOA, −0.8–2.1 −3.7–1.8 C5H8,10N2O8, C5H9N3O10, C10H17N3O13. fast reaction rate constants (estimated be order 10–13 cm3 molecules–1 s–1 at 295 K) lower result increased SOA yields when availability increases enhanced. Specifically, increase up 300% yield observed N2O5/isoprene 3:1; 5.7% (organic mass concentration, ΔMo 4.2 μg/m3) 16.3% (ΔMo 11.9 reacted 25 ppb 3.1% 1.2 12.4% 5.4 15 ppb. maximum occurs greater or equal 3:1 a combined peroxy radicals (RO2) fate. We encourage future studies consider factors, can vary laboratory ambient conditions, comparing better understand any differences observed. Our results highlight that updated parameters including distribution should considered enable more comprehensive representation prediction atmospheric models.

Language: Английский

Citations

2
Effects of a Carboxyl Group on the Products, Mechanism, and Kinetics of the OH Radical-Initiated Oxidation of 3-Butenoic Acid Under Low NOx Conditions DOI
Anna C. Ziola, Paul J. Ziemann

The Journal of Physical Chemistry A, Journal Year: 2025, Volume and Issue: unknown

Published: Feb. 4, 2025

Concentrations of nitrogen oxides (NOx) in the U.S. have decreased so much last few decades that oxidation volatile organic compounds (VOCs), which plays a critical role formation ozone and fine particles, now often occurs urban areas under conditions are historically associated with remote rural locations. As result, alkylperoxy radicals (RO2•), key intermediates VOC oxidation, can react NO, HO2, RO2• radicals, isomerize. In this study, we primarily investigated products, mechanism, kinetics OH radical-initiated 3-butenoic acid where dominant products similar reaction 1-pentene were hydroxy-hydroperoxides formed through + HO2 reactions. 3-Butenoic has some structural properties made it ideally suited for was conducted an environmental chamber using iodide chemical ionization mass spectrometry authentic standards. The major oxo-propanoic acid, hydroxyoxo-butanoic dihydroxy-butanoic dihydroxy-dicarboxybutyl-peroxide (a ROOR dimer) measured molar yields 0.74, 0.09, 0.08, 0.03 total yield 0.94 effectively achieved mole balance. Unlike reaction, radical led almost solely to formaldehyde apparently due hydrogen bonding involving carboxyl group ROO–OOH intermediate complex. Similar ROO–OOR complex likely responsible peroxide dimer exceptional speed reactions, competitive reactions calculated from measurements modeling occur rate constant ≥3 × 10–11 cm3 molecule–1 s–1 may approach collision limit value about 5 10–10 s–1. results study demonstrate functional groups dramatic effects on atmospheric chemistry VOCs.

Language: Английский

Citations

0