The Chemistry of Formazan Dyes. Synthesis and Characterization of a Stable Verdazyl Radical and a Related Boron-Containing Heterocycle
Bibliographic record
Abstract
This experiment describes the synthesis and characterization of a formazan dye, and its subsequent conversion to a stable verdazyl radical and a boron–nitrogen heterocycle (boratatetrazine). Each of these compounds is intensely colored and is prepared and handled under aerobic conditions, which often surprises students as free radicals are generally described as short-lived, highly reactive species and compounds containing boron are often assumed to be air-sensitive. The prepared compounds are studied by 1 H and 13 C NMR, UV–vis, and EPR spectroscopy. The UV–vis spectra introduce an opportunity to discuss the different energy transitions that may give rise to intense colors, and interpretation of the EPR spectrum requires the student to carefully consider the bonding within the verdazyl radical; that is, is the radical centered on one atom or is it shared over several atoms within the structure? In addition the crystal structures of the formazan and the boratatetrazine are viewed in detail, expanding the students knowledge of bonding in delocalized 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) | 0.003 | 0.001 |
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".