Bibliographic record
Abstract
[497-23-4] C4H4O2 (MW 84.07) InChI = 1S/C4H4O2/c5-4-2-1-3-6-4/h1-2H,3H2 InChIKey = VIHAEDVKXSOUAT-UHFFFAOYSA-N (can be transformed into derivatives of 2-furanol including esters2 and silyl ethers;3 provides 3-(1′-hydroxyalkyl)-2(5H)-furanones by regioselective aldolization;4 undergoes highly regio- and stereoselective reactions with sulfinylallyl anions;5 serves as keystone for the convergent assembly of lignans6 and prostaglandin analogs7 through tandem vicinal difunctionalization8) Alternate Names: γ-crotonolactone; 2(5H)-furanone; but-2-en-4-olide. Physical Data: bp 86–87 °C/12 mmHg; mp 5 °C; d 1.185 g cm−3. A pKa value of 18.8 has been determined for its equilibrium acidity in DMSO (pKHA), but this may not be correct.9 Solubility: sol most organic solvents, e.g. CCl4, CH2Cl2, Et2O, toluene, THF, MeOH, and MeCN. Form Supplied in: colorless or pale yellow liquid, commercially available; expensive. Preparative Methods: obtainable by oxidation of furfural10 or by dehydrobromination of α-bromo-γ-butyrolactone10a,11 at very low cost. Handling, Storage, and Precautions: avoid contact with skin or eyes; do not inhale or ingest; vapor is irritating to the eyes and upper respiratory track. It should be stored at 4 °C or below. Use in a fume hood.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
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) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| 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) | 0.036 | 0.015 |
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".