Oxidation of secondary hydroperoxides via αC–H abstraction to form ketones and hydroxyl radicals: fluorene autoxidation as a model system
Bibliographic record
Abstract
Organic and biological molecules with relatively weak C–H bonds can react with O2 via a free-radical reaction called autoxidation. The primary products of these peroxyl-radical-driven reactions are hydroperoxides, R2CHOOH. If autoxidation continues, the secondary oxidation of hydroperoxides is known to form ketones, R2C═O, but this mechanism is not well characterized. Importantly, we find that ketone formation produces a highly reactive hydroxyl radical, HO•. We can trap HO• using benzene as a solvent to form quantifiable amounts of phenol. Fluorene was chosen as a model system to study this secondary oxidation in great detail. Kinetic modeling allowed the measurement of rate constants for the primary and secondary autoxidation reactions as 11.3 and 25 mol L−1s−1, respectively. Density functional theory modeling likewise predicts a faster oxidation for the secondary autoxidation. This type of kinetic measurement and modeling approach could be useful to study the autoxidation of plastics, petrochemicals, and lipids.
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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 | 0.000 |
| 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 | 0.000 | 0.001 |
| 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".