Thermodynamics of mixtures containing alkoxyethanols: Part XVII ERAS characterization of alkoxyethanol + alkane systems
Bibliographic record
Abstract
Alkoxyethanol + alkane systems have been examined in the framework of the ERAS model. An exact expression for the molar excess heat capacity at constant pressure, CPE, of solutions formed by a self-associated compound and an inert solvent has been derived. The CPE and the molar excess enthalpies (HE) and excess volumes (VE), as well as the molar enthalpies of vaporization of the pure alkoxyethanols, are represented accurately by ERAS. The calculated curves for HE and VE are skewed towards high mole fractions of the alkane. The experimental curves are more symmetrical. The opposite behaviour is observed for CPE in solutions with 2-ethoxyethanol, 2-propoxyethanol, or 2-butoxyethanol. The differences between the experimental and theoretical values arise because ERAS does not properly take into account the enhanced dipoledipole interactions due to the formation of intramolecular H-bonds in alkoxyethanols. As in previous applications, ERAS cannot simultaneously represent molar excess Gibbs energies and liquidliquid equilibria. DISQUAC, a purely physical theory, improves ERAS predictions for HE (except at high temperatures and pressures) and for CPE. Liquidliquid equilibria are also described more consistently. The self-association of alkoxyethanols via intramolecular H-bonds and the strong dipoledipole interactions lead to values of the self-association enthalpy and of the adjustable parameter of the physical contribution to HE and VE that are higher than those of the homomorphic 1-alkanols. In contrast, the equilibrium constants are lower. There is good agreement between the partial molar excess enthalpies at 298.15 K and infinite dilution of 2-alkoxyethanol in 2-alkoxyethanol(1) + n-heptane(2) mixtures and the values of the self-association enthalpies. Key words: alkoxyethanol, intermolecular, intramolecular, H-bond, dipoledipole interactions.
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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 | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.001 |
| Open science | 0.000 | 0.001 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.002 | 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".