The ozonolysis of <i>ortho</i>-xylene and its relevance to the history of the benzene problem
Bibliographic record
Abstract
Using B3LYP density functional theory in conjunction with the 6-311++G** basis set, the relative rates of the initial rate-determining attack of ozone upon the carboncarbon bonds of o-xylene are found to be 4,5- [Formula: see text] 3,4- > 2,3- > 1,2-. With the assumption that the final products glyoxal (G), methylglyoxal (M), and dimethylglyoxal (D) are determined by the site of the initial attack, and taking statistical factors into account, the ratio G:M:D is calculated to be 3:2:1. This is close to the value found experimentally, and identical to the result predicted by the contention that two nearly equivalent KekuléPauling valence bond (resonance) structures of o-xylene exist and each localized carboncarbon double bond of these structures is oxidized at the same rate. Although Frontier Molecular Orbital theory also predicts a 3:2:1 ratio of G:M:D, this theory incorrectly predicts that the initial attack of ozone will take place at the 1,2- and 4,5- bonds, with 1,2-attack slightly preferred. These results are discussed in relation to a recent historical analysis of the benzene problem, and it is concluded that since the products of ozonolysis of o-xylene are determined by the relative energies of the transition states leading to the four possible primary ozonides, these transition states should be the focus of theory.Key words: Kekulé structure, resonance, frontier orbital theory, density functional theory, kinetics.
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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) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.000 | 0.001 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.001 | 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".