A Mechanistic Study of the Brønsted-Acid Catalysis of<i>n-</i>Hexane → Propane + Propene, Featuring Carbonium Ions
Bibliographic record
Abstract
A hypothetical five-step catalytic cycle for Brønsted-mediated fission of an all-trans n- alkane was examined using density functional theory. Optimized geometries and transition states were determined for catalyst−reactant complexes, using three different monodentate catalyst ions (NH 4 +, H 3 O +, and H 2 F + ). Despite the wide variety of catalyst acidities, protonated hexane appears as an intermediate (not a transition state) in each case. The protonated cyclopropane structure is the most likely initial form of the dissociated product ion. The predicted intermediates were seen to vary with catalyst acidity. The complete energy profiles of this model catalytic cycle are provided and fitted to a cosine expansion, which allows for generation of the energy profile for any Brønsted catalyst and any n- alkane only on the basis of the proton affinities of the n- alkane and the conjugate base of the catalyst. Remarks on the applicability to zeolites and ionic liquid catalysts are given.
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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) | 0.001 | 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".