Fluorene

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Not to be confused with fluorine.

Fluorene^[1]



IUPAC name 9H-Fluorene
Identifiers
CAS number	86-73-7^Y
PubChem	6853
ChemSpider	6592^Y
UNII	3Q2UY0968A^Y
EC number	201-695-5
KEGG	C07715^Y
ChEBI	CHEBI:28266^Y
ChEMBL	CHEMBL16236^Y
RTECS number	LL5670000
Jmol-3D images	Image 1
SMILES c1ccc-2c(c1)Cc3c2cccc3
InChI InChI=1S/C13H10/c1-3-7-12-10(5-1)9-11-6-2-4-8-13(11)12/h1-8H,9H2^Y Key: NIHNNTQXNPWCJQ-UHFFFAOYSA-N^Y InChI=1/C13H10/c1-3-7-12-10(5-1)9-11-6-2-4-8-13(11)12/h1-8H,9H2 Key: NIHNNTQXNPWCJQ-UHFFFAOYAW
Properties
Molecular formula	C₁₃H₁₀
Molar mass	166.223 g/mol
Density	1.202 g/mL
Melting point	116-117 °C
Boiling point	295 °C; 563 °F; 568 K
Solubility in water	1.992 mg/L
Solubility	soluble in CS₂, ether, benzene, hot alcohol, pryimidine, CCl₄, toluene, acetone
log P	4.18
Acidity (pK_a)	22.6
Hazards
MSDS	Sigma-Aldrich
NFPA 704	1 1 0
Flash point	152 °C; 306 °F; 425 K
LD₅₀	16000 mg/kg (oral, rat)
Y (verify) (what is: Y/N?) Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
Infobox references

Fluorene /flɔriːn/, or 9H-fluorene, is a polycyclic aromatic hydrocarbon. It forms white crystals that exhibit a characteristic, aromatic odor similar to that of naphthalene. It is combustible. It has a violet fluorescence, hence its name. For commercial purposes it is obtained from coal tar. It is insoluble in water and soluble in benzene and ether.

Synthesis, structure, and reactivity

Although fluorene is obtained from coal tar, it can also be prepared by dehydrogenation of diphenylmethane.^[2]

Alternatively, it can be prepared by the reduction of diphenylene with zinc.

The fluorene molecule is nearly planar,^[3] although each of the two benzene rings is coplanar with the central carbon 9.^[4]

Acidity

The C9-H sites of the fluorene ring are weakly acidic (pK_a = 22.6 in DMSO.^[5]) Deprotonation gives the stable fluorenyl "anion", nominally C₁₃H₉⁻, which is aromatic and has an intense orange colour. The anion is a nucleophile, and most electrophiles react with it by adding to the 9-position. The purification of fluorene exploits its acidity and the low solubility of its sodium derivative in hydrocarbon solvents.

Both protons can be removed from C9. For example, 9,9-fluorenyldipotassium can be obtained by treating fluorene with potassium metal in boiling dioxane.^[6]

Uses

Fluorene is a precursor to other fluorene compounds; the parent species has few applications. Fluorene-9-carboxylic acid is a precursor to pharmaceuticals. 2-Aminofluorene, 3,6-bis-(dimethylamino)fluorene, and 2,7-diiodofluorene are precursors to dyes. Oxidation of fluorene gives fluorenone, which is nitrated to give commercially useful derivatives. 9-Fluorenylmethyl chloroformate (Fmoc chloride) is used to introduce the 9-fluorenylmethyl carbamate (Fmoc) protecting group on amines in peptide synthesis.^[2]

Polyfluorene polymers (where carbon 7 of one unit is linked to carbon 2 of the next one, displacing two hydrogens) are electrically conductive and electroluminescent, and have been much investigated for use as a luminophore in organic light-emitting diodes.

References

↑ Merck Index, 11th Edition, 4081
↑ 2.0 2.1 Karl Griesbaum, Arno Behr, Dieter Biedenkapp, Heinz-Werner Voges, Dorothea Garbe, Christian Paetz, Gerd Collin, Dieter Mayer, Hartmut Höke “Hydrocarbons” in Ullmann's Encyclopedia of Industrial Chemistry 2002 Wiley-VCH, Weinheim. doi:10.1002/14356007.a13_227
↑ D. M. Burns, John Iball (1954), Molecular Structure of Fluorene Nature volume 173, p. 635. doi:10.1038/173635a0
↑ R. E. Gerkin, A. P. Lundstedt and W. J. Reppart (1984) Structure of fluorene, C₁₃H₁₀, at 159 K Acta Crystallographica, volume C40, pp. 1892–1894 doi:10.1107/S0108270184009963
↑ F. G. Bordwell (1988). "Equilibrium acidities in dimethyl sulfoxide solution". Acc. Chem. Res. 21 (12): 456–463. doi:10.1021/ar00156a004.
↑ G. W. Scherf and R. K. Brown (1960), POTASSIUM DERIVATIVES OF FLUORENE AS INTERMEDIATES IN THE PREPARATION OF C9-SUBSTITUTED FLUORENES. I. THE PREPARATION OF 9-FLUORENYL POTASSIUM AND THE INFRARED SPECTRA OF FLUORENE AND SOME C9-SUBSTITUTED FLUORENES. Canadian Journal of Chemistry, Vol. 38, p. 697.

External links

National Pollutant Inventory - Polycyclic Aromatic Hydrocarbon Fact Sheet
Fluorene in the National Institute of Standards and Technology database.

v t e Polycyclic aromatic hydrocarbons

2 rings	Azulene Naphthalene 1-Methylnaphthalene Sapotalin

3 rings	Acenaphthene Acenaphthylene Anthracene Fluorene Phenalene Phenanthrene

4 rings	Benz[a]anthracene Benzo[a]fluorene Benzo[c]phenanthrene Chrysene Fluoranthene Pyrene Tetracene Triphenylene Tricyclobutabenzene

5 rings	Benzopyrene Benzo[a]pyrene Benzo[e]pyrene Benzo[a]fluoranthene Benzo[b]fluoranthene Benzo[j]fluoranthene Benzo[k]fluoranthene Dibenz[a,h]anthracene Dibenz[a,j]anthracene Olympicene Pentacene Perylene Picene Tetraphenylene

6+ rings	Anthanthrene Benzo[ghi]perylene Circulene Corannulene Coronene Dicoronylene Diindenoperylene Helicene Heptacene Hexacene Kekulene Ovalene Zethrene

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