Aqueous OH kinetics of saturated C6–C10 dicarboxylic acids under acidic and basic conditions between 283 and 318 K; new structure-activity relationship parameters

Witkowski, Bartłomiej; Chi, Jian; Jain, Priyanka; Błaziak, Kacper; Gierczak, Tomasz

doi:10.1016/j.atmosenv.2021.118761

Cited by 4 publications

(13 citation statements)

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“…However, the k OH values measured here for some TAs were lower than the values obtained using pure standards. , The estimated k SAR values (Table S5) were also noticeably higher than the k OH values measured in this work (Table ). , Therefore, k OH values measured here for lower-MW products are likely affected by their secondary formation in the reaction solution. ,− , Previously, only the formation of terpenylic acid ( m / z 171) was observed from reaction under very similar conditions . Note, however, that the authors did not compare their results with SAR predictions and used slightly outdated kinetic data; their study was focused on a lower number of TAs, which might explain these discrepancies.…”

Section: Resultsmentioning

confidence: 75%

“…The k OH values measured in this work under acidic and basic conditions for cis -pinic, cis -pinonic, and 4-oxopinonic acids are generally in good agreement with the previously reported data (Table ). However, the k OH values measured here for some TAs were lower than the values obtained using pure standards. , The estimated k SAR values (Table S5) were also noticeably higher than the k OH values measured in this work (Table ). , Therefore, k OH values measured here for lower-MW products are likely affected by their secondary formation in the reaction solution. ,− , Previously, only the formation of terpenylic acid ( m / z 171) was observed from reaction under very similar conditions .…”

Section: Resultsmentioning

confidence: 99%

“…Kinetic reference compounds, suberic, camphoric, azelaic, and sebacic acid, were added to the reaction solution before photooxidation. The pH of the reaction mixture was adjusted to 2 or 9 with HClO 4 or NaOH to measure the k OH values for the completely protonated and deprotonated TAs with p K a values between 4 and 5 …”

Section: Methodsmentioning

confidence: 99%

“…49,51 The estimated k SAR values (Table S5) were also noticeably higher than the k OH values measured in this work (Table 2). 49,51 Therefore, k OH values measured here for lower-MW products are likely affected by their secondary formation in the reaction solution. 29,[31][32][33]89 Previously, only the formation of terpenylic acid (m/z 171) was observed from reaction 1 under very similar conditions.…”

Section: Kinetic Measurementsmentioning

confidence: 99%

“…Aqueous processing (aging) of terpenoic precursors by the OH, which is the major atmospheric oxidant during the daytime, , recently received attention as the potential source of aq SOAs. ,,,− The kinetic data available to date strongly indicate that OH oxidation of TAs is likely to occur under realistic atmospheric conditions. ,,, Aqueous OH aging of the water-soluble fraction of α-P SOA (α-P SOA aq ) yielded low-volatility, oxidized products ,, but was also shown to decompose dimers. , …”

Section: Introductionmentioning

confidence: 99%

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Aging of α-Pinene Secondary Organic Aerosol by Hydroxyl Radicals in the Aqueous Phase: Kinetics and Products

Witkowski

Alsharafi

Błaziak

et al. 2023

Environ. Sci. Technol.

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The reaction of hydroxyl radicals (OH) with a water-soluble fraction of the α-pinene secondary organic aerosol (SOA) was investigated using liquid chromatography coupled with negative electrospray ionization mass spectrometry. The SOA was generated by the dark ozonolysis of α-pinene, extracted into the water, and subjected to chemical aging by the OH. Bimolecular reaction rate coefficients (k OH) for the oxidation of terpenoic acids by the OH were measured using the relative rate method. The unaged SOA was dominated by the cyclobutyl-ring-retaining compounds, primarily cis-pinonic, cis-pinic, and hydroxy-pinonic acids. Aqueous oxidation by the OH resulted in the removal of early-stage products and dimers, including well-known oligomers with MW = 358 and 368 Da. Furthermore, a 2- to 5-fold increase in the concentration of cyclobutyl-ring-opening products was observed, including terpenylic and diaterpenylic acids and diaterpenylic acid acetate as well as some of the newly identified OH aging markers. At the same time, results obtained from the kinetic box model showed a high degree of SOA fragmentation following the reaction with the OH, which indicates that non-radical reactions occurring during the evaporation of water likely contribute to the high yields of terpenoic aqSOAs reported previously. The estimated atmospheric lifetimes showed that in clouds, terpenoic acids react with the OH exclusively in the aqueous phase. Aqueous OH aging of the α-pinene SOA results in a 10% increase of the average O/C ratio and a 3-fold decrease in the average k OH value, which is likely to affect the cloud condensation nuclei activity of the aqSOA formed after the evaporation of water.

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