A theoretical kinetic study on the reaction of atomic bromine with toluene
Bibliographic record
Abstract
Abstract The reaction of Br atoms with toluene was investigated by employing various quantum chemical methods and statistical rate theory calculations. Various composite methods such as CBS‐QB3, G3, and G4 were used to obtain the energy profiles of the Br + toluene reaction. Further single‐point calculations of the stationary points were performed at the CCSD(T)/cc‐pV(D,T)Z level of theory using B3LYP/cc‐pVTZ and MP2/aug‐cc‐pVDZ optimized geometries. Our calculations revealed several reaction pathways in the potential energy surface of the Br + toluene reaction. However, the reaction pathway that abstracts hydrogen atoms from the methyl site of toluene was found to be energetically the most favorable. This reaction pathway appears to proceed via a complex forming mechanism, similar to that seen in the reactions of cyclic ethers with Br atoms. Our calculations reveal that the reaction of a Br atom with toluene proceeds exclusively via intermediate complexes in an overall endothermic addition‐elimination mechanism. Based on the ab initio results, the standard enthalpies of formation of the product radicals and the rate coefficients for the relevant reaction pathways are computed. The calculated values of the enthalpy of formation are found to match excellently with the available literature data. Lowering the barrier height of hydrogen abstraction reaction at the methyl site by less than 4 kJ/mol, the calculated rate coefficients, k ov ( T ) = 1.36 × 10 –23 T 3.687 exp(−4.57 K/ T ) cm 3 molecule –1 s –1 , reproduced the experimental data excellently from 200 to 500 K.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| 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 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| 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 teacher head, 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".