Ab Initio/RRKM Study of Dissociation Mechanism of Benzene Trication
Bibliographic record
Abstract
Density functional B3LYP /6-31 G (d,p) calculations have been performed in order to investigate isomerization and dissociation of [Formula: see text] in the ground electronic state, which are relevant to the Coulomb explosion mechanism of benzene. The results demonstrate that the benzene-like isomer of [Formula: see text], 1, can decompose through various pathways leading to distinct fragmentation products. The most kinetically favorable channel involves ring opening in 1 accompanied with 1,2-shifts of two hydrogen atoms followed by rotation around the middle C–C bond and dissociation to H 2 CCCH 2+ + H 2 CCCH + with exothermicity and the highest barrier of 100.2 and 38.4 kcal/mol, respectively. Several other product channels, including [Formula: see text], [Formula: see text], [Formula: see text], and [Formula: see text], share the same highest barrier for the initial ring opening step with the pathway producing H 2 CCCH 2+ + H 2 CCCH + but exhibit higher second highest barriers. Elimination of [Formula: see text] to form [Formula: see text] is 137.9 kcal/mol exothermic but the highest barrier on the pathway leading to these products is 53.0 kcal/mol. A simple proton elimination to produce [Formula: see text] is computed to be 82–84 kcal/mol exothermic and to depict a 64–65 kcal/mol barrier. RRKM calculations of rate constants for individual reaction steps assuming that the initial internal energy of 1 is 110 kcal/mol and solving kinetic master equations to obtain relative branching ratios show that H 2 CCCH 2+ + H 2 CCCH + are the dominant products (81.5%) followed by [Formula: see text] (13.2%) and the other minor products include [Formula: see text] (2.6%), [Formula: see text] (1.1%), [Formula: see text] (0.55%), [Formula: see text] (0.49%), [Formula: see text] (0.20%), and [Formula: see text] (0.14%). The fragments are expected to be produced with high translational energy due to high Coulomb repulsion energy barriers.
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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 | 0.001 | 0.001 |
| Meta-epidemiology (narrow) | 0.001 | 0.001 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.002 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.002 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.007 | 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".