Chemistry:Lithium naphthalenide
 A solution of lithium naphthalenide in tetrahydrofuran
| |
| Names | |
|---|---|
| Preferred IUPAC name
Lithium naphthalenide | |
| Other names
LN
| |
| Identifiers | |
3D model (JSmol)
|
|
| ChemSpider | |
PubChem CID
|
|
| |
| |
| Properties | |
| Li+ [C 10H 8]− | |
| Molar mass | 135.11 g·mol−1 |
| Appearance | Dark green crystals |
| Solubility | Soluble in ether, benzene, THF[1] |
| Related compounds | |
Other cations
|
sodium naphthalenide |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). | |
| Infobox references | |
Lithium naphthalenide is an organic salt with the chemical formula Li+
[[[Chemistry:Carbon|C]]
10H
8]−
. In the research laboratory, it is used as a reductant in the synthesis of organic, organometallic, and inorganic chemistry. It is usually generated in situ. Lithium naphthalene crystallizes with ligands bound to Li+
.[2] The anion is a well-known example of an organic radical.
Preparation and properties
The compound is prepared by stirring the metallic lithium with naphthalene in an ethereal solvent, usually as tetrahydrofuran or dimethoxyethane. The resulting salt is dark green.[3] The reaction of naphthalene with lithium can be accelerated by sonication. Methods for assaying lithium naphthalene have been developed as well.[4] As a radical, its solutions show a strong EPR signal near g = 2.0.[5] Its deep green color arises from absorptions at 463 and 735 nm.[6]
Several solvates of lithium naphthalene have been characterized by X-ray crystallography. The effects are subtle, the outer pair of HC–CH bonds contract by 3 pm and the other nine C–C bonds elongate by 2–3 pm. Net reduction weakens the bonding.[7]
Reactions
Reductant
With a reduction potential near −2.5 V versus the normal hydrogen electrode, the naphthalene radical anion is a strong reducing agent.[6] Lithium naphthalene has often been used to cleave carbon-heteroatom bonds.[8][1]
Protonation
The anion is strongly basic, and a typical degradation pathway involves reaction with water and related protic sources such as alcohols. These reactions give dihydronaphthalene:[9]
As a ligand precursor
Alkali metal salts of the naphthalene radical anion are used to prepare complexes of naphthalene.[10]
Related compounds
Many related radical anions are known such as those derived from anthracene, with other alkali metals (especially sodium), and with diverse ligands attached to the alkali metal cations such as [Li+
(tmeda)
2]
2[C
10H
8]2−.[11][2]
References
- ↑ 1.0 1.1 Short, Kevin M.; Wei, Alexander; Padungros, Panuwat (2014). "Lithium Naphthalenide". Encyclopedia of Reagents for Organic Synthesis. pp. 1–6. doi:10.1002/047084289X.rl131.pub2. ISBN 978-0-470-84289-8.
- ↑ 2.0 2.1 Melero, Cristóbal; Guijarro, Albert; Yus, Miguel (2009). "Structural Characterization and Bonding Properties of Lithium Naphthalene Radical Anion, Li+(TMEDA)2C10H−8, and Lithium Naphthalene Dianion (Li+TMEDA)2C10H2−8". Dalton Transactions (8): 1286–1289. doi:10.1039/b821119c. PMID 19462646.
- ↑ David G. Hilmey; Leo A. Paquette (2007). "1,3-Dichloroacetone as a Cyclopropanone Equivalent: 5-Oxaspiro[3.4]Octan-1-one". Organic Syntheses 84: 156. doi:10.15227/orgsyn.084.0156.
- ↑ Nicholas A. Morra and Brian L. Pagenkopf (2008). "Direct Synthesis of 2,5-Dihalosiloles". Organic Syntheses 85: 53. doi:10.15227/orgsyn.085.0053.
- ↑ Cotton, F. Albert; Wilkinson, Geoffrey (1988), Advanced Inorganic Chemistry (5th ed.), New York: Wiley-Interscience, p. 139, ISBN 0-471-84997-9
- ↑ 6.0 6.1 Connelly, Neil G.; Geiger, William E. (1996). "Chemical Redox Agents for Organometallic Chemistry". Chemical Reviews 96 (2): 877–910. doi:10.1021/cr940053x. PMID 11848774.
- ↑ Castillo, Maximiliano; Metta-Magaña, Alejandro J.; Fortier, Skye (2016). "Isolation of Gravimetrically Quantifiable Alkali Metal Arenides Using 18-Crown-6". New Journal of Chemistry 40 (3): 1923–1926. doi:10.1039/C5NJ02841H.
- ↑ Gao, Jian-Wu (2012). "Lithium Naphthalenide". Synlett (2): 317–318. doi:10.1055/s-0031-1290127.
- ↑ Elliott, M.C.; Hewitt, N.L. (2014). "8.19 Partial Reduction of Benzenoid Aromatic Rings by Dissolving Metals and by Other Methods". Comprehensive Organic Synthesis II. pp. 639–672. doi:10.1016/B978-0-08-097742-3.00821-1. ISBN 978-0-08-097743-0.
- ↑ Ellis, John E. (2019). "The Chatt Reaction: Conventional Routes to homoleptic Arenemetalates of d-Block Elements". Dalton Transactions 48 (26): 9538–9563. doi:10.1039/C8DT05029E. PMID 30724934.
- ↑ Brooks, J. J.; Rhine, Wendell; Stucky, G. D. (1972). "π-Groups in Ion Pair Bonding. Stabilization of the Dianion of Naphthalene by Lithium Tetramethylethylenediamine". Journal of the American Chemical Society 94 (21): 7346–7351. doi:10.1021/ja00776a014. Bibcode: 1972JAChS..94.7346B.
 |  |
