New methods for resolution of hydroxychloroquine by forming diastereomeric salt and adding chiral mobile phase agent on RP‐HPLC
Bibliographic record
Abstract
Abstract Hydroxychloroquine (HCQ), 2‐([4‐([7‐Chloro‐4‐quinolyl]amino)pentyl]ethylamino)ethanol, exhibited significant biological activity, while its side effects cannot be overlooked. The RP‐HPLC enantio‐separation was investigated for cost‐effective and convenient optical purity analysis of HCQ. The thermodynamic resolution of Rac‐HCQ, driven by enthalpy and entropy, was achieved on the C18 column using Carboxymethyl‐β‐cyclodextrin (CM‐β‐CD) as the chiral mobile phase agent (CMPA). The effects of CCM‐β‐CD, pH, and triethylamine (TEA) V% on the enantio‐separation process were explored. Under the optimum conditions at 24°C, the retention times for the two enantiomers were and , resulting in . The resolution via diastereomeric salt formation of Rac‐HCQ was developed to obtain the active pharmaceutical ingredient of single enantiomer S‐HCQ. Di‐p‐Anisoyl‐L‐Tartaric Acid (L‐DATA) was proved effective as the resolution agent for Rac‐HCQ. Surprisingly, it was found that refluxing time was a key fact affecting the resolution efficiency, which meant the kinetic dominate during the process of the resolution. Four factors—solvent volume, refluxing time, filtration temperature, and molar ratio—were optimized using the single‐factor method and the response surface method. Two cubic models were established, and the reliability was subsequently verified. Under the optimal conditions, the less soluble salt of 2L‐DATA:S‐HCQ was obtained with a yield of 96.9% and optical purity of 63.0%. The optical purity of this less soluble salt increases to 99.0% with a yield of 74.2% after three rounds recrystallization.
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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 | 0.001 | 0.001 |
| 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 | 0.000 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.002 | 0.002 |
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".