Hydration of Phenylketene Revisited: A Counter-Intuitive Result
Bibliographic record
Abstract
In previous work (Can. J. Chem. 1987, 65, 1719-1723 and J. Am. Chem. Soc. 1995, 117, 9165-9171), flash photolysis of diazoacetophenone or phenylhydroxycyclopropenone in aqueous solution was found to produce phenylketene as a short-lived transient species with absorbance at lambda congruent with 260 nm, which decayed with single-exponential kinetics. It has now been discovered that, in the acidity region [H(+)] = 0.000 01 to 0.06 M, this decay is preceded by a faster absorbance rise, and that the overall change conforms well to a double exponential rate law. Analysis of the new data produces rate profiles whose general shapes, as well as the numerical values of their constituent rate constants, plus the form of buffer catalysis, indicate that this newly discovered absorbance rise represents ketonization of phenylacetic acid enol, and that the subsequent absorbance decay represents addition of water to phenylketene. The chemistry of the system, however, requires ketene hydration to precede enol ketonization in a time sequence opposite from that of the absorbance changes. This seemingly counter-intuitive result is nevertheless consistent with the rate law that governs the time evolution of the central species in a two-step rise and decay, such as that observed here.
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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 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.001 |
| 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) | 0.000 | 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".