Allylic H-Abstraction Mechanism: The Potential Energy Surface of the Reaction of Propene with OH Radical
Bibliographic record
Abstract
The allylic H-atom abstraction reaction plays a more dominant role, especially at lower temperature, than addition reactions in the case of the CH2 [Formula: see text] CH-CH3 + •OH system. Different computational methods including ab initio as well as density functional methods have been used to examine allylic H-abstraction. Both the energetically less favorable direct H-abstraction and the more favorable indirect H-abstractions have been investigated. Using first principles computations, for the indirect abstraction, a stable π- or reactantlike as well as a late productlike complex were found on the potential energy surface. Based on higher level single point calculations (QCISD(T)/6-311+G(3df,2p)), a new activation enthalpy value, Δ(⧧)H° = 0.3 ± 2 kJ/mol, is suggested for the title reaction. The computed reaction enthalpy ΔrH° = -124.7 ± 2 kJ/mol is in good agreement with the experimental value. The stability of the initial π-complex was found to be ΔH°π-complex = -7.1 kJ/mol. The product complex between the transition state and the product was found with the stability of -127.2 kJ/mol.
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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 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.001 | 0.000 |
| Insufficient payload (model declined to judge) | 0.005 | 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".