Kinetics and Dissociation Constants (<i>pK<sub>a</sub></i>) of Polyamines of Importance in Post-Combustion Carbon Dioxide (CO<sub>2</sub>) Capture Studies
Bibliographic record
Abstract
Pseudo-first-order overall rate constants for the loss of CO2 via reaction with different types of amines were measured using a stopped-flow technique at 298.15 K. Polyamines and cyclic amines were found to have higher reaction rates than linear primary and secondary amines. Therefore, six aqueous cyclic polyamine solutions were studied at (298.15 to 313.15) K over a concentration range of (20 to 120) mol·m-3 using. The overall reaction orders were calculated using the empirical power law kinetics and were found to be fractional in order, for practically all studied cyclic polyamines. The overall rate constants were fitted with the Crooks-Donnellan termolecular rate expression to determine elementary rate constants. In addition, the dissociation constants (pKa ) were determined using the potentiometric titration method at (298, 303, 313 and 323) K, and predicted using quantum chemistry techniques (IEFPCM continuum solvation model). A trend was found for the variation of the pKa with the addition of different radical groups to the cyclic base molecules. Computational techniques tested for the prediction of pKa involved B3LYP and MP2 levels of electronic structure theory, the addition of an explicit water molecule inside the continuum cavity, and a special scaling of the cavity radii for the ions. The procedure developed in this study reduced the error found in a previous technique for cyclic amines by 62%.
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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 | 0.000 |
| Meta-epidemiology (narrow) | 0.001 | 0.001 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.000 | 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".