Theoretical Study of the Rate Constants and Kinetic Isotope Effects of the 1,2-Hydrogen-Atom Shift of Methoxyl and Benzyloxyl Radicals Assisted by Water
Bibliographic record
Abstract
Rate constants and kinetic isotope effects for the 1,2-H shift of methoxyl and benzyloxyl radicals were studied in the presence of water molecules. The electronic structure calculations were carried out at the UB3LYP/6-31G* level, and the dynamics calculations were performed using the variational transition state theory with semiclassical multidimensional corrections for tunneling. The study deals with 1:1 and 1:2 radical-water complexes in the gas phase. It was found that water catalyzes these rearrangement reactions by forming a bridge containing two water molecules. The dynamics calculations show that the methoxyl-water complexes react only very slowly. The rate constants for 1:2 complexes with the benzyloxyl radical are in relative good agreement with the results of laser flash photolysis. The kinetic isotope effects calculated using heavy water indicate that tunneling makes an important contribution in the 1:1 complex, whereas the contribution due to vibrations is more important for the 1:2 complexes. In both cases, the kinetic isotope effects are substantial. It is concluded that the 1,2-H shift for both radicals is catalyzed by two water molecules through a mechanism that involves the formation of a preliminary 1:1 complex.
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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) | 0.001 | 0.001 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.001 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.003 | 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".