Keto−Enol/Enolate Equilibria in the Isochroman-4-one System. Effect of a β-Oxygen Substituent
Bibliographic record
Abstract
The enol of 1-tetralone was generated flash photolytically, and rates of its ketonization were measured in aqueous HClO4 and NaOH solutions as well as in CH3CO2H, H2PO4(-), (CH2OH)3CNH3(+), and NH4(+) buffers. The enol of isochroman-4-one was also generated, by hydrolysis of its potassium salt and trimethylsilyl ether, and rates of its ketonization were measured in aqueous HClO4 and NaOH. Rates of enolization of the two ketones were measured as well. Combination of the enolization and ketonization data for isochroman-4-one gave the keto-enol equilibrium constant pK(E) = 5.26, the acidity constant of the enol ionizing as an oxygen acid p = 10.14, and the acidity constant of the ketone ionizing as a carbon acid p = 15.40. Comparison of these results with those for 1-tetralone shows that the beta-oxygen substituent in isochroman-4-one raises all three of these constants: K(E) by 2 orders of magnitude, by not quite 1 order of magnitude, and by nearly 3 orders of magnitude. The beta-oxygen substituent also retards the rate of hydronium-ion-catalyzed ketonization by more than 3 orders of magnitude. The origins of these substituent effects are discussed.
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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 | 0.001 |
| Open science | 0.000 | 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".