Methyl Radical Addition Reactions to C═X Double Bonds
Bibliographic record
Abstract
High Resolution Image Download MS PowerPoint Slide Radical additions to olefins and related π-systems are essential tools in the modern synthetic toolbox for forging C–C and C–X bonds. We report a systematic DFT study (ZORA-(U)OLYP/TZ2P) on methyl radical (H 3 C • ) additions to H 2 C═X substrates, where X is varied across elements from the tetrel (group 14: C, Si, Ge), pnictogen (group 15: N, P, As), and chalcogen (group 16: O, S, Se) groups. Our analysis reveals clear periodic trends: addition barriers at carbon decrease, and those at X increase from tetrels to chalcogens; reaction energies become less favorable across a period but more favorable down a group. Regioselectivity favors addition at X except for X = CH 2, NH, and O, where carbon attack dominates─consistent with experimental data. These trends arise from a balance of orbital interactions and Pauli repulsion, with the latter emerging as a key, yet underappreciated, factor governing radical reactivity and regioselectivity in π-systems.
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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) | 0.004 | 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".