Kinetic Study of the Mechanism of the Low-Temperature Pyrolysis of Vinyl Bromide
Bibliographic record
Abstract
The pyrolysis of vinyl bromide has been examined in the temperature range 637−733 K and at pressures from 6 to 86 kPa. The yields of the major hydrocarbon products, C 2 H 2, C 2 H 4, and 1,3-C 4 H 6, are second order in vinyl bromide over the entire range of temperatures investigated. At the higher temperatures, initiation by molecular elimination of HBr dominates, while at lower temperatures a free radical initiation channel becomes increasingly important. Our data for the overall process leading to HBr fit the relation ln( k ) = (30.7 ± 4.8) − ((26.6 ± 3.3) × 10 3 )/ T, with the rate constant in the units L mol -1 s -1, indicating an activation energy of 220 kJ mol -1 ± 12% for the HBr elimination. A simple Arrhenius extrapolation is close to previous results at temperatures from 800 to over 2000 K. The combination of our data and the earlier measurements of the HBr elimination is reasonably represented by ln( k ) = 37 − (3 × 10 4 )/ T . Our data suggest that the free radical pathway is disproportionation rather than unimolecular cleavage of the C−Br bond, a situation analogous to that in the low-temperature thermal decomposition of ethylene. Kinetic analysis indicates that the activation energy of this new free radical initiation channel is approximately 150 kJ mol -1, much less than the C−Br bond energy.
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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 | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.001 | 0.001 |
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".