Indene
| Indene | |
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1H-indene |
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Other names
benzocyclopentadiene |
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| Identifiers | |
| CAS number | 95-13-6  |
| PubChem | 7219 |
| ChemSpider | 6949 |
| DrugBank | DB02815 |
| KEGG | C11565 |
| ChEBI | CHEBI:41921 |
| ChEMBL | CHEMBL192812 |
| Jmol-3D images | Image 1 |
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| Properties | |
| Molecular formula | C9H8 |
| Molar mass | 116.16 |
| Acidity (pKa) | 20.1 (in DMSO)[1] |
 (verify) (what is:  / ?)Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) |
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| Infobox references | |
Indene is a flammable polycyclic hydrocarbon with chemical formula C9H8. It is composed of a benzene ring fused with a cyclopentene ring. This aromatic liquid is colorless although samples often are pale yellow. The principal industrial use of indene is in the production of indene/coumarone thermoplastic resins.
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Isolation [edit]
Indene occurs naturally in coal-tar fractions boiling around 175–185 °C. It can be obtained by heating this fraction with sodium to precipitate solid "sodio-indene." This step exploits indene's weak acidity evidenced by its deprotonation by sodium to give the indenyl derivative. The sodio-indene is converted back to indene by steam distillation.[2]
Reactivity [edit]
Indene readily polymerises. Oxidation of indene with acid dichromate yields homophthalic acid (o-carboxylphenylacetic acid). It condenses with ethyl oxalate in the presence of sodium ethoxide to form indene-oxalic ester, and with aldehydes or ketones in the presence of alkali to form benzofulvenes. The latter are highly coloured. An indene is also a precursor to the indenyl anion, a ligand in organometallic chemistry with some notability due to the indenyl effect.
See also [edit]
References [edit]
- ^ Bordwell FG (1988). "Equilibrium acidities in dimethyl sulfoxide solution". Accounts of Chemical Research 21 (12): 456–463. doi:10.1021/ar00156a004. Bordwell pKa Table in DMSO
- ^ Gerd Collin, Rolf Mildenberg, Mechthild Zander, Hartmut Höke, William McKillip, Werner Freitag, Wolfgang Imöhl “Resins, Synthetic” Ullmann's Encyclopedia of Industrial Chemistry Wiley-VCH, Weinheim, 2000.
See also [edit]
- W. v. Miller, Rohde (1890). "Zur Synthese von Indenderivaten". Berichte der deutschen chemischen Gesellschaft 23 (2): 1881–1886. doi:10.1002/cber.18900230227.
- W. v. Miller, Rohde (1890). "Zur Synthese von Indenderivaten". Berichte der deutschen chemischen Gesellschaft 23 (2): 1887–1902. doi:10.1002/cber.18900230228.
- Finar, I. L. (1985). Organic Chemistry. Longman Scientific & Technical. ISBN 0-582-44257-5.
