Indene

Bicyclic hydrocarbon compound with formula C9H8

Indene  Skeletal formula

Names
Preferred IUPAC name

1H-Indene[1]

Other names

Benzocyclopentadiene
Indonaphthene
Bicyclo[4.3.0]nona-1,3,5,7-tetraene

Identifiers

CAS Number

* 95-13-6 Y

3D model (JSmol)

* Interactive image

Beilstein Reference

| 635873
ChEBI |

* CHEBI:41921 Y

ChEMBL |

* ChEMBL192812 Y

ChemSpider |

* 6949 Y

DrugBank |

* DB02815 Y

ECHA InfoCard | 100.002.176
EC Number |

* 202-393-6

Gmelin Reference

| 27265
KEGG |

* C11565 Y

PubChem CID

* 7219

UNII |

* 67H8Y6LB8A Y

CompTox Dashboard (EPA)

* DTXSID8042052

InChI

* InChI=1S/C9H8/c1-2-5-9-7-3-6-8(9)4-1/h1-6H,7H2 Y

Key: YBYIRNPNPLQARY-UHFFFAOYSA-N Y

* InChI=1/C9H8/c1-2-5-9-7-3-6-8(9)4-1/h1-6H,7H2

Key: YBYIRNPNPLQARY-UHFFFAOYAJ

SMILES

* c1ccc2c(c1)CC=C2

Properties

Chemical formula

| C9H8
Molar mass | 116.16
Appearance  | Colorless liquid[2]
Density | 0.997 g/mL
Melting point | −1.8 °C (28.8 °F; 271.3 K)
Boiling point | 181.6 °C (358.9 °F; 454.8 K)

Solubility in water

| Insoluble
Acidity (pKa)  | 20.1 (in DMSO)[3]

Magnetic susceptibility (χ)

| −80.89×10−6 cm3/mol
Hazards
Occupational safety and health (OHS/OSH):

Main hazards

| Flammable
Flash point | 78.3 °C (172.9 °F; 351.4 K)
NIOSH (US health exposure limits):

PEL (Permissible)

| none[2]

REL (Recommended)

| TWA 10 ppm (45 mg/m3)[2]

IDLH (Immediate danger)

| N.D.[2]
Related compounds

Related compounds

| Benzofuran, Benzothiophene, Indole

Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).

Y verify (what is YN ?)

Infobox references

Chemical compound

Indene is an aromatic, polycyclic hydrocarbon with chemical formula C9H8. It is composed of a benzene ring fused with a cyclopentene ring. This flammable liquid is colorless although samples often are pale yellow. The principal industrial use of indene is in the production of indene/coumarone thermoplastic resins. Substituted indenes and their closely related indane derivatives are important structural motifs found in many natural products and biologically active molecules, such as sulindac.[4]

## 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.[5]

## Reactivity

[edit]

Indene readily polymerises. Oxidation of indene with acid dichromate yields homophthalic acid (o-carboxylphenylacetic acid). It condenses with diethyl 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, which are highly coloured. Treatment of indene with organolithium reagents gives lithium indenyl compounds:

C9H8 \+ RLi → LiC9H7 \+ RH

Indenyl is a ligand in organometallic chemistry, giving rise to many transition metal indenyl complexes.[6]

## See also

[edit]

* Indane
* Indole
* Isoindene
* Indenyl effect
* Indenone

## References

[edit]

1. ^ International Union of Pure and Applied Chemistry (2014). Nomenclature of Organic Chemistry: IUPAC Recommendations and Preferred Names 2013. The Royal Society of Chemistry. p. 207\. doi:10.1039/9781849733069. ISBN 978-0-85404-182-4.
2. ^ a b c d NIOSH Pocket Guide to Chemical Hazards. "#0340". National Institute for Occupational Safety and Health (NIOSH).
3. ^ 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 Archived 2008-10-09 at the Wayback Machine
4. ^ Wu, Jie; Qiu, Guanyinsheng (2014). "Generation of Indene Derivatives by Tandem Reactions". Synlett. 25 (19): 2703–2713\. doi:10.1055/s-0034-1379318.
5. ^ Collin, Gerd; Mildenberg, Rolf; Zander, Mechthild; Höke, Hartmut; McKillip, William; Freitag, Werner; Imöhl, Wolfgang (2000). "Resins, Synthetic". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. ISBN 978-3-527-30673-2.
6. ^ O'Connor, Joseph M.; Casey, Charles P. (1987). "Ring-Slippage Chemistry of Transition Metal Cyclopentadienyl and Indenyl Complexes". Chemical Reviews. 87 (2): 307–318\. doi:10.1021/cr00078a002.

## External links

[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.

Authority control databases: National |

* Germany

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*[CID]: Compound ID
*[EPA]: U.S. Environmental Protection Agency