Free Radicals Formed by H Atom Addition to Allenes as Determined by Muon Spin Spectroscopy
Bibliographic record
Abstract
Allyl and vinyl radicals are important intermediates in diverse areas of chemistry, ranging from combustion to synthesis. However, questions remain about the competitive formation of these radicals from allenes. Here, we present a study of prototypical allyl and vinyl radicals formed by H atom addition to allenes. They were studied by forming the analogous muonium adducts because muonium (Mu) behaves as a light isotope of hydrogen, and muoniated species can be characterized by muon spin spectroscopy (μSR). Two techniques were employed: transverse-field muon spin rotation (TF-μSR) and muon level-crossing resonance (μLCR), which allow for the measurement of muon hyperfine constants (hfcs) and other nuclear hfcs, respectively, and thus aid identification of the formed radicals. TF-μSR has already been used to determine that two radicals are formed by Mu addition to 1,1-dimethylallene, but μLCR techniques were undeveloped at the time of that study, so assignments were based on electron spin resonance (ESR) data of similar allyl and vinyl radicals. We report here the μSR of multiple radicals detected from positive muon irradiation of 1,1-dimethylallene and 1-methoxyallene in solution. The radicals were identified by comparison of muon and proton hfcs with ESR data and the results of density functional theory calculations. The conclusion is that muonium (and by extension, the H atom) can add to all three carbons of the allene system, albeit with preference for the central carbon.
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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) | 0.000 | 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 | 0.000 |
| 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".