Experimental Determination of Activation Energies for Gas-Phase Ethyl and <i>n</i>-Propyl Cation Transfer Reactions
Bibliographic record
Abstract
Alkyl cation transfer reactions between ethanol and protonated ethanol and ethanol and protonated propionitrile, as well as between n -propanol and protonated n -propanol have been investigated experimentally by low-pressure Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometry. The two ethyl cation transfer reactions were found to be the dominant reaction channels with association being only a minor reaction pathway. The n -propyl cation transfer reaction was found to compete with the association pathway resulting in an approximately 50:50 mixture of protonated di- n -propyl ether and the proton-bound dimer of n -propanol, depending on temperature and pressure. The enthalpies of activation were determined to be −16.1 ± 0.8, −17.5 ± 0.8, and −15.7 ± 0.9 kJ mol -1 for the ethanol/protonated ethanol, ethanol/protonated propionitrile, and n -propanol/protonated n -propanol alkyl cation transfer reactions, respectively. The entropies of activation were found to be essentially the same, −121 ± 28 J K -1 mol -1, for all three reactions. All experimentally determined thermochemical properties agreed very well with those calculated at the MP2/6-31+G(d)//B3LYP/6-31+G* level of theory. Furthermore, the enthalpies and entropies of activation for the methy, ethyl, and n -propyl cation transfer reactions between the neutral alcohols and the respective protonated alcohols were found to be the same within experimental uncertainty.
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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 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.000 | 0.001 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.005 | 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".