Indene

Indene
Names
	Preferred IUPAC name 1H-Indene
	Other names Benzocyclopentadiene; Indonaphthene; Bicyclo[4.3.0]nona-1,3,5,7-tetraene
Identifiers
CAS Number	95-13-6 ;
3D model (JSmol)	Interactive image;
Beilstein Reference	635873
ChEBI	CHEBI:41921 ;
ChEMBL	ChEMBL192812 ;
ChemSpider	6949 ;
DrugBank	DB02815 ;
EC Number	202-393-6;
Gmelin Reference	27265
KEGG	C11565 ;
PubChem CID	7219;
UNII	67H8Y6LB8A ;
	InChI InChI=1S/C9H8/c1-2-5-9-7-3-6-8(9)4-1/h1-6H,7H2 Key: YBYIRNPNPLQARY-UHFFFAOYSA-N ; 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	C; 9H; 8
Molar mass	116.16
Appearance	Colorless liquid
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)
Magnetic susceptibility (χ)	−80.89×10−6 cm3/mol
Hazards
Main hazards	Flammable
Flash point	78.3 °C (172.9 °F; 351.4 K)
	NIOSH (US health exposure limits):
PEL (Permissible)	none
REL (Recommended)	TWA 10 ppm (45 mg/m3)
IDLH (Immediate danger)	N.D.
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).
	verify (what is ?)
	Infobox references

Short description: Bicyclic hydrocarbon compound with formula C9H8

Indene is an aromatic, polycyclic hydrocarbon with chemical formula C
9H
8. 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

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

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:

[math]\ce{ C9H8 + RLi -> LiC9H7 + RH }[/math]

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

References

↑ International Union of Pure and Applied Chemistry (2014). Nomenclature of Organic Chemistry: IUPAC Recommendations and Preferred Names 2013. The Royal Society of Chemistry. pp. 207. doi:10.1039/9781849733069. ISBN 978-0-85404-182-4.
↑ ^2.0 ^2.1 ^2.2 ^2.3 NIOSH Pocket Guide to Chemical Hazards. "#0340". National Institute for Occupational Safety and Health (NIOSH). https://www.cdc.gov/niosh/npg/npgd0340.html.
↑ 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
↑ Wu, Jie; Qiu, Guanyinsheng (2014). "Generation of Indene Derivatives by Tandem Reactions". Synlett 25 (19): 2703–2713. doi:10.1055/s-0034-1379318.
↑ Collin, Gerd; Mildenberg, Rolf; Zander, Mechthild; Höke, Hartmut; McKillip, William; Freitag, Werner; Imöhl, Wolfgang. "Ullmann's Encyclopedia of Industrial Chemistry". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH.
↑ 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

W. v. Miller, Rohde (1890). "Zur Synthese von Indenderivaten". Berichte der Deutschen Chemischen Gesellschaft 23 (2): 1881–1886. doi:10.1002/cber.18900230227. https://zenodo.org/record/1425600.
W. v. Miller, Rohde (1890). "Zur Synthese von Indenderivaten". Berichte der Deutschen Chemischen Gesellschaft 23 (2): 1887–1902. doi:10.1002/cber.18900230228. https://zenodo.org/record/1425559.
Finar, I. L. (1985). Organic Chemistry. Longman Scientific & Technical. ISBN 0-582-44257-5.

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[1] International Union of Pure and Applied Chemistry (2014). Nomenclature of Organic Chemistry: IUPAC Recommendations and Preferred Names 2013. The Royal Society of Chemistry. pp. 207. doi:10.1039/9781849733069. ISBN 978-0-85404-182-4.

[PGCH-2] 2.0 ^2.1 ^2.2 ^2.3 NIOSH Pocket Guide to Chemical Hazards. "#0340". National Institute for Occupational Safety and Health (NIOSH). https://www.cdc.gov/niosh/npg/npgd0340.html.

[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

[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. "Ullmann's Encyclopedia of Industrial Chemistry". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH.

[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.

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Indene

Topic: Chemistry

Contents

Isolation

Reactivity

See also

References

External links

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
EC Number	202-393-6
Gmelin Reference	27265
KEGG	C11565^Y
PubChem CID	7219
UNII	67H8Y6LB8A^Y
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	C 9H 8
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 (pK_a)	20.1 (in DMSO)^[3]
Magnetic susceptibility (χ)	−80.89×10⁻⁶ cm³/mol
Hazards
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