Dissociation Constant (p<i>K</i><sub>a</sub>) and Thermodynamic Properties of Some Tertiary and Cyclic Amines from (298 to 333) K
Bibliographic record
Abstract
The potentiometric titration method was used to measure p K a values of nine amines [2-(diisopropylamino)ethanol [2-DIPA], N, N, N ′, N ′-tetrakis(2-hydroxypropyl)ethylenediamine [THPEDA], 2-{[2-(dimethylamino) ethyl]methyl amino} ethanol [2-DMAEMAE], tris[2-(2-methoxyethoxy)ethyl]amine [TMEEA], N -(2-hydroxyethyl) aniline [2-HEAN], 1-(2-hydroxyethyl)piperazine [HEP], piperazine [PZ], monoethanolamine [MEA], and N -methyldiethanolamine [MDEA] at (298.15, 303.15, 313.15, 323.15, and 333.15) K. p K a values of the last three amines were compared with published data to validate the procedure and assess the accuracy of the instrument. Thermodynamic quantities, such as standard enthalpy (Δ H °·kJ –1 ·mol –1 ) and entropy (Δ S o ·kJ –1 ·mol –1 ) for the dissociation process, were determined at 298.15 K using the van’t Hoff equation. From the experimental results, the values of the standard state thermodynamic properties were derived and compared to the values of commercially available amines used as absorbents for CO 2 capture. Among the studied amines, 2-DMAEMAE was identified as having a high p K a (9.18) and lower heat of dissociation than MEA (27.77 kJ/mol, as compared to 48.59 kJ/mol for MEA) and can therefore be considered a potential candidate for CO 2 capture applications.
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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 | 0.001 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.001 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.003 | 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".