A theoretical model study on the cyclic reaction of 4-hydroxybutanal catalyzed by Brønsted acid
Bibliographic record
Abstract
For a theoretical model study on the cyclic reaction of 4-hydroxybutanal (4-OH-BL), we have examined five assumed reaction pathways (I–V) by performing the B3LYP calculations in the gas phase and self-consistent isodensity polarized continuum model (SCIPCM)-B3LYP calculations in aqueous solution. Pathways II (4-OH-BL + H + ), III (4-OH-BL + H 3 O + ), and IV (4-OH-BL + H 3 O + + H 2 O) represent three models for the cyclic reaction catalyzed by Brønsted acids. The present study leads to the following conclusions concerning the five pathways (mainly on the basis of the calculation results in the solution). The high barrier along pathway I (with no catalyst) implies that the reaction does not occur without a catalyst, and the extremely large stabilization energy of the intermediate implies that pathway II is not a realistic model for the reaction catalyzed by Brønsted acid. Along pathway III, there are two intermediates and a transition state in between, and they are 10–16 kcal/mol lower in energy than the reactants (4-OH-BL + H 3 O + ). Along pathway IV, there is only one intermediate, and it is 20.6 kcal/mol lower in energy than the reactants (4-OH-BL + H 3 O + + H 2 O). Pathways III and IV are predicted to be feasible. Energetically, pathway IV is more favourable than pathway III and it is considered as a rational model for the cyclic reaction of 4-OH-BL catalyzed by Brønsted acid. Our calculations for pathway V (catalyzed by H 2 O) indicate that the water molecule may also serve as a catalyst for the cyclic reaction. The transition state along pathway V is 20.0 kcal/mol higher in energy than the reactants (4-OH-BL + H 2 O), and one can clearly see the “proton wire” in its structure. Our calculations show strong solvent effects on energetics of the charged intermediates along pathways II, III, and IV.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.001 |
| 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 | 0.001 |
| 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 teacher head, 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".