Theoretical investigation on the reaction mechanisms of <scp>O<sub>2</sub></scp>‐initiated gas‐phase oxidation of lignin model compounds
Bibliographic record
Abstract
Abstract Transforming renewable lignin into high value‐added chemicals is a forward‐looking strategy to address the resource waste caused by insufficient utilization of biomass resources. On this basis, studying the efficient conversion of lignin to aldehydes/acids and their reaction mechanisms has become an attractive topic. A systematic investigation of the gas‐phase oxidation reaction mechanisms of the three model compounds initiated by O2 was carried out at the atomic and molecular levels by using density functional theory (DFT). Further revealing of oxidation behavior on two reaction sites of phenolic hydroxyl group and hydroxymethyl group were accomplished in detail. The potential energy surface information of 21 possible reaction channels of two pathways were obtained at B3LYP/6‐311+G(d,p) level. The influence of substituent effects on the reaction energy barrier was estimated. The calculation results showed that the reactivity of phenolic hydroxyl group is stronger than that of hydroxymethyl group, because the reaction Gibbs potential barriers are lower by about 4.9–8.7 kcal/mol. The reaction energy barriers on phenolic hydroxyl group site and hydroxymethyl group site decrease with the increase of the number of methoxy groups. Revealing the oxidation processes of lignin model compounds will provide a deeper understanding on the reaction mechanism and provide theoretical support for further experimental research on the conversion of lignin into high value‐added chemicals.
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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 | 0.001 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.000 | 0.001 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.001 | 0.000 |
| Insufficient payload (model declined to judge) | 0.004 | 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".