Resolution Characteristics of Optically Active (1 <scp> <i>S</i> </scp> ,2 <scp> <i>S</i> </scp> )‐(+)‐1‐( <scp> <i>p</i> </scp> ‐Nitrophenyl)‐2‐Amino‐1,3‐Propanediol for <scp> <i>trans</i> </scp> ‐1,2‐Cyclohexanedicarboxylic Acid
Bibliographic record
Abstract
The resolution behavior of chiral compounds containing two carboxyl groups remains an interesting subject due to their potential for forming complex stereospecific interactions. In this study, a representative for this group of compounds, trans-1,2-cyclohexanedicarboxylic acid (CHDA) was enantiomerically separated using optically active (1S,2S)-(+)-1-(p-nitrophenyl)-2-amino-1,3-propanediol ((SS)-ANP) as a resolving agent in ethanol solvent. Remarkably, regardless of the initial molar ratio of (SS)-ANP to CHDA (ranging from 1:3 to 3:1), only a cocrystal, di-(SS)-ANP·CHDA·ethanol was obtained. When the molar ratio was adjusted to 1:2, a pair of diastereomeric salts was formed, and (RR)-CHDA freed from the less soluble diastereomeric salt exhibited an enantiomeric excess (e.e.) exceeding 85%. Upon two cycles of recrystallization of the less soluble salts, the optical purity of the freed (RR)-CHDA reached 96.5 e.e.%. To elucidate the resolution mechanism, single crystals of both the less soluble salt 2(SS)-ANP·(RR)-CHDA·ethanol and the more soluble salt 2(RR)-ANP·(RR)-CHDA·ethanol were grown and structurally analyzed. The crystallographic data revealed that the hydrogen bonding in the less soluble salt was stronger than that in the more soluble salt, enhancing the stability of the less soluble salt, 2(SS)-ANP·(RR)-CHDA·ethanol.
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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 | 0.000 | 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 | 0.000 |
| 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 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".