Kinetics of the gas-phase reaction of atomic chlorine with selected monoterpenes
Bibliographic record
Abstract
Halogens may play an important role in the chemistry of hydrocarbons in certain regions of the troposphere. We have studied Cl-atom-initiated reactions of several monoterpenes (α-pinene, 2-carene, 3-carene, myrcene and γ-terpinene) at atmospheric pressure of ca. 760 Torr over the temperature range 283–323 K in N2 and air. The decay of the terpenes was followed using a gas chromatograph with a flame ionisation detector (GC-FID) and the rate constants were determined using the relative rate technique with n-nonane as a reference compound. The Cl atoms were generated by UV photolysis of trichloroacetylchloride (CCl3COCl) at λ≅250 nm. Room temperature rate constants are found to be (in units of 10−10 cm3 molecule−1 s−1, with uncertainties representing ± 2σ) 5.3 ± 0.1 for α-pinene, 5.8 ± 0.1 for 2-carene, 5.2 ± 0.1 for 3-carene, 8.5 ± 1.8 for myrcene, and 10.4 ± 0.6 for γ-terpinene. No temperature dependence was observed for the reactions within our experimental uncertainties with the exception of Cl + γ-terpinene (ln k = (−27.9 ± 0.8) − (2100 ± 200)/T). Data on the rate constants of the Cl reactions with monoalkenes and dienes, obtained in this work and taken from the literature were correlated with alkene HOMO energies within the framework of PFMO theory. The calculated semi-empirical parameters can be used to predict Cl-atom rate constants for alkenes in the troposphere. To gain a deeper insight into the reaction mechanism, several ab initio and DFT quantum chemical calculations were also carried out.
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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 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.002 | 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".