Ion Rearrangement at the Beginning of Cluster Formation: Methyl Substitution Effects on the Internal S <sub>N</sub> 2 Reaction in the Proton-Bound Dimers of Acetonitrile and Alcohols
Bibliographic record
Abstract
Mass spectrometry and ab initio calculations have been employed to investigate the unimolecular decompositions of proton-bound dimers consisting of acetonitrile with n- and i-propanol. Common to both systems is a competition between dissociation of the hydrogen bond in the proton-bound dimer and isomerization to (CH 3 CNR)(H 2 O) + [R = CH 2 CH 2 CH 3 and CH(CH 3 ) 2 ]. The minimum-energy-reaction pathways for the isomerization in these two systems, as well as those for the dimers containing methanol and ethanol, are presented and compared. The dominant isomerization pathway for these ions is an internal S N 2 reaction that proceeds via a stable intermediate CH 3 CN•••ROH 2 + ion [R = CH 3 , CH 2 CH 3 , CH 2 CH 2 CH 3 and CH(CH 3 ) 2 ]. The mass spectra for the four butanol-containing dimers ( n-, s-, i- and t-butanol) follow similar behavior.
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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 | 0.000 | 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".