Reaction of Condensed-Phase Criegee Intermediates with Carboxylic Acids and Perfluoroalkyl Carboxylic Acids
Bibliographic record
Abstract
This work presents evidence for the formation of α-acyloxyalkyl-1-hydroperoxides (AAHPs) from the reaction of carboxylic acids with Criegee intermediates formed by gas-phase ozone reacting heterogeneously with a condensed-phase alkene, squalene. With liquid chromatography-electrospray-tandem mass spectrometry, it is shown that a long-chain fatty acid, palmitic acid, is lost when squalene is exposed to ozone in the presence of palmitic acid. This is consistent with the formation of higher molecular weight products via Criegee intermediate reactions observed by direct analysis in real-time mass spectrometry. Confirmation of AAHP formation comes from application of a new atmospheric pressure chemical ionization-tandem mass spectrometry method that is specific to organic hydroperoxides. Experiments with perfluorotetradecanoic acid confirm that the perfluoroalkyl carboxylic acids, a class of compounds that was heretofore thought to be unreactive in the condensed phase, can also be lost via reactions with Criegee intermediates in this manner. Condensed-phase water competes with this reaction, likely leading to α-hydroxyhydroperoxides via the direct reaction of water with the Criegee intermediates. The potential environmental importance of this chemistry is discussed in terms of the fate of perfluoroalkyl carboxylic acids, secondary organic aerosol formation, and oxidation of organic films in indoor settings.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.001 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.001 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.001 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".