Chiral Resolution of 1,1'-binaphthalene-2,2'-diol and its (-)- Menthyl Chloroformate Derivatives by High Performance Liquid Chromatography with Urea Derivative as Chiral Stationary Phase
Bibliographic record
Abstract
The chiral resolution of 1,1'-binaphthalene-2,2'-diol (1), 1,1'-binaphthalene-2,2'-diol-mono-[(-)-menthyl] carbonate(2) and 1,1'-binaphthalene-2,2'-diol-bi-[(-)-menthyl] carbonate(3) was studied by high performance liquid chromatography using (S)-tert-leucine and (S)-1-α-NEA as chiral stationary phase. The effect of different content of 1,2-dichloroethane and ethane, as well as a different polar modifier in mobile phase on the chiral separation was discussed. A baseline separation of optical isomers of compounds 1 and 2 with n-hexane/1,2- dichloroethane/ethanol(82∶16∶2, V/V/V) as mobile phase was obtained. The optical isomers first eluted are S-2 and R-1, their capacity factors are 0.159 and 1.196, separation factors are 1.779 and 1.311,resolutions are 2.444 and 4.266, respectively. The optical isomers of compound 3 are only partially resolved. The likely role of double hydrogen bonding between 1,1'-binaphthalene-2,2'-diol and (S)-tert-leucine (S)-1-α-NEA as well as steric hindrance for the chiral recognition and separation was discussed. This method was applied to identify the optical purity of the samples from the resolution of racemic 1,1'-binaphthalene-2,2'-diol.
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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 | 0.001 |
| 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 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".