Rate and equilibrium constants for formation and hydrolysis of 9-formylfluorene oxime: diffusion-controlled trapping of a protonated aldehyde by hydroxylamine
Bibliographic record
Abstract
Equilibrium constants K add = 440 and K ox = 3.0 × 10 8 for formation of a carbinolamine adduct and oxime, respectively from 9-formylfluorene and hydroxylamine, and pK a = 1.62 for protonation of the oxime, have been evaluated at 25°C in aqueous solution, based on measurements in hydroxylamine buffers, acetic acid buffers, and dilute HCl. Rate constants for hydrolysis of the oxime have been measured in the acidity range pH 412 M HClO 4 . At the highest acidities, a reaction pathway via protonated carbinolamine has been identified: evidence is presented that the reverse of this reaction involves rate-determining attack of hydroxylamine upon protonated 9-formylfluorene. By assuming that the attack of hydroxylamine is diffusion-controlled, with rate constant 3 × 10 9 M 1 s 1 , a pK a for O-protonation of the aldehyde (4.5) is derived. Taking account of the equilibrium constant for enolization of 9-formylfluorene (K E = 16.6), a pK a for for C-protonation of the enol tautomer ((5.7) may also be obtained. Comparison of this pK a with that of the enol of acetophenone shows that the enol of 9-formylfluorene is less basic by a factor of 10 10 . By combining pK a s for protonation of the aldehyde and oxime with measured or estimated equilibrium constants for addition of water, hydroxide ion, and hydroxylamine to 9-formylfluorene, it is also possible to obtain values of pK R = 5.3, 4.1, and 12.25 for the protonated 9-formylfluorene, protonated oxime, and 9-formylfluorene, respectively. The usefulness of pK R in providing a general measure of equilibrium constants for electrophile-nucleophile combination reactions is discussed.Key words: oxime, formyfluorene, hydrolysis, protonation, diffusion-control.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 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 teacher head, 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".