Geometry and energy of amidoenethiolate conformers formed by ring-opening of several thiazolium ions in base: a theoretical study using density functional theory
Bibliographic record
Abstract
An interesting aspect of the ring-opening of thiamine and certain other thiazolium ions is the biphasic kinetics of the ring reclosure process.It has previously been proposed that the two amide rotamers of the ring-opened amidoenethiolates are responsible for the two kinetic processes.We have carried out Hartree-Fock and density functional theory calculations on a series of amidoenethiolates and their corresponding tetrahedral intermediates.The corrected gas phase energy difference of 14.6 kJ/mol between 1′c and 2′c supports the notion that the two rotamers can exist in solution in sufficient quantities to give rise to two kinetic processes.The major enethiolate conformer should cyclize more rapidly (after protonation) than the minor conformer in agreement with previous observations.The most stable tetrahedral intermediate has a geometry that suggests stabilization by the anomeric effect.
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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 | 0.001 | 0.000 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.000 | 0.001 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.001 | 0.000 |
| Insufficient payload (model declined to judge) | 0.003 | 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".