Bibliographic record
Abstract
[2223-58-7] C5H10Li2 (MW 84.02) InChI = 1S/C5H10.2Li/c1-3-5-4-2;;/h1-5H2;; InChIKey = QQDSVXYDUMVTSQ-UHFFFAOYSA-N (constructing block agent: transformations of carboxyl groups and metal halides into cyclohexane and metallacyclohexane synthetic intermediates, and α,ω-bifunctional compounds; in presence of CuI ion, the reagent is transformed into an organobiscuprate) Alternate Name: 1,5-pentanediyldilithium. Solubility: sol ether, THF, hydrocarbons. Form Supplied in: prepared in ether and used in solutions which usually range from 0.5 to 1.2 M. Analysis of Reagent Purity: titration;2 1H NMR α-CH2 signal δ −0.81 (t, J = 9 Hz);3 quenching with chlorotrimethylsilane;3, 4 GLC.5 Preparative Methods: was first prepared by direct reaction of 1,5-dibromopentane with Lithium metal at 0 °C in anhydrous ether.4, 8 This method was later improved by using lithium metal (4 equiv) containing 1% Na with 1,5-dichloropentane (1 equiv).5 The optimum procedure9 uses a 12.5% excess of lithium and maintains the temperature at 0 °C (eq 1). Yields up to 90% can be obtained by this method, which may also serve to prepare lower analogs. (1) The Barbier procedure, under ultrasonic irradiation, may also be used. In a particular case, 1,5-dibromopentane (2 equiv), methyl R(−)-2-methyloctanoate (1 equiv) and lithium (8 equiv) were reacted in THF at −25 °C for 25 min (see eq 3).10 1,5-Dilithiopentane can also be prepared by lithium–iodine exchange between t‐Butyllithium and 1,5-diiodopentane (eq 2).3 This method requires a temperature of −78 °C and 4 equiv of t-BuLi.2 The excess of reagent is important, as a stoichiometric amount leads to the corresponding cycloalkane almost quantitatively. (2) The procedure also generates, in excellent yields, lithio compounds from homoallylic-type iodides. Alkyl bromides and secondary iodides may also be used, but yields are lower. Handling, Storage, and Precautions: solutions are highly flammable; must be stored and handled in the absence of proton sources, carbon acids, and oxygen. Flasks and Schlenk tubes should be flushed with dry Ar or N2. At −20 °C, ether solutions have a useful life of one to four months.5, 6 At higher temperature (∼30 °C), organolithiums react readily with ethers.7
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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) | 0.001 | 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 | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.019 | 0.010 |
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".