A Kinetic Analysis of the Effect of O<sub>2</sub> on the Reactions of Atomic Bromine with Some Hydrocarbons and Ethers
Bibliographic record
Abstract
The kinetics of the reactions of atomic bromine with ethene, 2-methylpropane, dimethyl ether, and diethyl ether have been studied at 298 K in a 70-L photochemical reaction chamber with the relative rate method. Chemical analysis was by gas chromatography with a flame ionization detector. The effects of bromine and oxygen partial pressure and of the choice of reference reactant on the numerical values of the rate constants obtained have been evaluated. The results are analyzed to obtain limiting values of the rate constant ratio that are independent of the concentration of O 2 and do not depend on the mechanism used to represent the overall reaction. The following rate constants were obtained at 298 K by using the well-established rate constant for the reaction of Br with 2-methylpropane as the primary reference: Br + (CH 3 ) 2 O, k 298 = 9.43 × 10 5 L mol -1 s -1 ± 2%; Br + (C 2 H 5 ) 2 O, k 298 = 1.41 × 10 7 L mol -1 s -1 ± 6%. With the rate constants for Br + (CH 3 ) 2 O as a secondary reference value, the rate constant at 298 K for Br + (C 2 H 5 ) 2 O was 1.27 × 10 7 L mol -1 s -1 ± 8% calculated at a limiting high concentration of O 2 . When Br + (C 2 H 5 ) 2 O was measured relative to Br + C 2 H 4, the rate constant at 298 K, calculated for limiting high concentrations of O 2, ranged from 4.7 × 10 7 to 1.2 × 10 7 L mol -1 s -1 depending on the rate constant chosen for the reference reaction. The sensitivity to oxygen concentration of the rate constant for the reaction of Br with ethene depends on the concentration of Br 2 used as the photolytic source of atomic bromine. When the reaction of Br with an organic reactant is sensitive to the presence of oxygen, measurements at O 2 concentrations much larger than those in synthetic air may be required to obtain reliable rate constants for the initial reaction of Br with the organic reactant.
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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) | 0.000 | 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 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".