Thermolysis of <i>N</i>‐tetramethylpiperidinyl triphenylacetate: homolytic fragmentation of a TEMPO ester
Bibliographic record
Abstract
Abstract Thermolysis of N‐tetramethylpiperidinyl triphenylacetate (7, Ph3CCO2T, T=2,2,6,6‐tetramethylpiperidinyl) in benzene at 146°C leads to the formation of triphenylmethane (Ph3CH, 80%), tetramethylpiperidine (TH, 91%), and tetraphenylmethane (Ph4C, 9%). First‐order rate constants for the decomposition at 132.8 and 150.0°C were 2.20 × 10−6 and 2.88 × 10−5 s−1, respectively. In benzene‐d6 solvent the triphenylmethane was formed as Ph3CD to the extent of 20%, as determined by 1H NMR and mass spectrometry. The results are interpreted as showing that Ph3CCO2T undergoes thermolysis by concerted two‐bond scission with formation of Ph3C⋅, tetramethylpiperidinyl radicals and CO2. The formation of Ph4C occurs by addition of Ph3C⋅ to benzene, followed by hydrogen atom abstraction from the resulting adduct. Calculations using DFT methods at the B3LYP/6–311++G** level were used to elucidate the bond fission of HCO2T (2), and indicate that cleavage to HCO2⋅ and T⋅ is favored by 7.8 kcal mol−1 relative to cleavage to HC(•)O and TO⋅, in agreement with the experimental results. Copyright © 2003 John Wiley & Sons, Ltd.
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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 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.002 | 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 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".