Fluorene

Fluorene^[1]
Names
	Preferred IUPAC name 9H-Fluorene
	Systematic IUPAC name Tricyclo[7.4.0.02,7]trideca-2,4,6,9,11,13-hexaene
Identifiers
CAS Number	86-73-7 ;
3D model (JSmol)	Interactive image;
ChEBI	CHEBI:28266 ;
ChEMBL	ChEMBL16236 ;
ChemSpider	6592 ;
EC Number	201-695-5;
KEGG	C07715 ;
PubChem CID	6853;
RTECS number	LL5670000;
UNII	3Q2UY0968A ;
	InChI InChI=1S/C13H10/c1-3-7-12-10(5-1)9-11-6-2-4-8-13(11)12/h1-8H,9H2 Key: NIHNNTQXNPWCJQ-UHFFFAOYSA-N ; 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;
	SMILES c1ccc2c3ccccc3Cc2c1;
Properties
Chemical formula	C13H10
Molar mass	166.223 g·mol−1
Density	1.202 g/mL
Melting point	116 to 117 °C (241 to 243 °F; 389 to 390 K)
Boiling point	295 °C (563 °F; 568 K)
Solubility in water	1.992 mg/L
Solubility	organic solvents
log P	4.18
Acidity (pKa)	22.6
Magnetic susceptibility (χ)	-110.5·10−6 cm3/mol
Hazards
Safety data sheet	Sigma-Aldrich
NFPA 704 (fire diamond)	1 1 0
Flash point	152 °C (306 °F; 425 K)
	Lethal dose or concentration (LD, LC):
LD50 (median dose)	16000 mg/kg (oral, rat)
	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

Fluorene /ˈflʊəriːn/, or 9H-fluorene is an organic compound with the formula (C₆H₄)₂CH₂. It forms white crystals that exhibit a characteristic, aromatic odor similar to that of naphthalene. It has a violet fluorescence, hence its name. For commercial purposes it is obtained from coal tar.^[3] It is insoluble in water and soluble in many organic solvents. Although sometimes classified as a polycyclic aromatic hydrocarbon, the five-membered ring has no aromatic properties. Fluorene is mildly acidic.

Synthesis, structure, and reactivity

Although fluorene is obtained from coal tar, it can also be prepared by dehydrogenation of diphenylmethane.^[3] Alternatively, it can be prepared by the reduction of fluorenone with zinc^[4] or hypophosphorous acid–iodine.^[5] The fluorene molecule is nearly planar,^[6] although each of the two benzene rings is coplanar with the central carbon 9.^[7]

Fluorene can be found after the incomplete combustion of plastics such as PS, PE and PVC.^[8]

Acidity

The C9-H sites of the fluorene ring are weakly acidic (pK_a = 22.6 in DMSO.^[9]) Deprotonation gives the stable fluorenyl anion, nominally C₁₃H₉⁻, which is aromatic and has an intense orange colour. The anion is a nucleophile. 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.^[10]

Ligand properties

Fluorene and its derivatives can be deprotonated to give ligands akin to cyclopentadienide.

A fluorenyl-derived Kaminsky precatalyst for producing syndiotactic polypropylene.^[11]

Uses

Fluorene is a precursor to other fluorene compounds; the parent species has few applications. Fluorene-9-carboxylic acid is a precursor to pharmaceuticals. 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.^[3]

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 as a luminophore in organic light-emitting diodes.

Fluorene dyes

Fluorene dyes are well developed. Most are prepared by condensation of the active methylene group with carbonyls. 2-Aminofluorene, 3,6-bis-(dimethylamino)fluorene, and 2,7-diiodofluorene are precursors to dyes.^[12]

References

↑ Merck Index, 11th Edition, 4081
↑ 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.
↑ ^3.0 ^3.1 ^3.2 Griesbaum, Karl; Behr, Arno; Biedenkapp, Dieter; Voges, Heinz-Werner; Garbe, Dorothea; Paetz, Christian; Collin, Gerd; Mayer, Dieter et al. (2000). "Ullmann's Encyclopedia of Industrial Chemistry". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/14356007.a13_227.
↑ Fittig, Rud. (1873), "Ueber einen neuen Kohlenwasserstoff aus dem Diphenylenketon" Ber. Dtsch. Chem. Ges. volume 6, p. 187.doi:10.1002/cber.18730060169
↑ Hicks, Latorya D.; Han, Ja Kyung; Fry, Albert J. (2000). "Hypophosphorous acid–iodine: a novel reducing system.". Tetrahedron Letters (Elsevier BV) 41 (41): 7817–7820. doi:10.1016/s0040-4039(00)01359-9. ISSN 0040-4039.
↑ D. M. Burns, John Iball (1954), Molecular Structure of Fluorene Nature volume 173, p. 635. doi:10.1038/173635a0
↑ Gerkin, R. E.; Lundstedt, A. P.; Reppart, W. J. (1984). "Structure of fluorene, C13H10, at 159 K". Acta Crystallographica Section C Crystal Structure Communications 40 (11): 1892–1894. doi:10.1107/S0108270184009963.
↑ Wang, Zhenlei; Richter, Henning; Howard, Jack B.; Jordan, Jude; Carlson, Joel; Levendis, Yiannis A. (2004-06-01). "Laboratory Investigation of the Products of the Incomplete Combustion of Waste Plastics and Techniques for Their Minimization". Industrial & Engineering Chemistry Research 43 (12): 2873–2886. doi:10.1021/ie030477u. ISSN 0888-5885. https://doi.org/10.1021/ie030477u.
↑ F. G. Bordwell (1988). "Equilibrium acidities in dimethyl sulfoxide solution". Acc. Chem. Res. 21 (12): 456–463. doi:10.1021/ar00156a004.
↑ G. W. Scherf; 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 38: 697. doi:10.1139/v60-100. .
↑ Ewen, J. A.; Jones, R. L.; Razavi, A.; Ferrara, J. D. (1988). "Syndiospecific Propylene Polymerizations with Group IVB Metallocenes". Journal of the American Chemical Society 110 (18): 6255–6256. doi:10.1021/ja00226a056. PMID 22148816.
↑ Kurdyukova, I. V.; Ishchenko, A. A. (2012). "Organic dyes based on fluorene and its derivatives". Russian Chemical Reviews 81 (3): 258–290. doi:10.1070/RC2012v081n03ABEH004211. Bibcode: 2012RuCRv..81..258K.

External links

Fluorene in the National Institute of Standards and Technology database.

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[1] Merck Index, 11th Edition, 4081

[2] 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.

[Ullmanns-3] 3.0 ^3.1 ^3.2 Griesbaum, Karl; Behr, Arno; Biedenkapp, Dieter; Voges, Heinz-Werner; Garbe, Dorothea; Paetz, Christian; Collin, Gerd; Mayer, Dieter et al. (2000). "Ullmann's Encyclopedia of Industrial Chemistry". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/14356007.a13_227.

[4] Fittig, Rud. (1873), "Ueber einen neuen Kohlenwasserstoff aus dem Diphenylenketon" Ber. Dtsch. Chem. Ges. volume 6, p. 187.doi:10.1002/cber.18730060169

[5] Hicks, Latorya D.; Han, Ja Kyung; Fry, Albert J. (2000). "Hypophosphorous acid–iodine: a novel reducing system.". Tetrahedron Letters (Elsevier BV) 41 (41): 7817–7820. doi:10.1016/s0040-4039(00)01359-9. ISSN 0040-4039.

[burns-6] D. M. Burns, John Iball (1954), Molecular Structure of Fluorene Nature volume 173, p. 635. doi:10.1038/173635a0

[7] Gerkin, R. E.; Lundstedt, A. P.; Reppart, W. J. (1984). "Structure of fluorene, C13H10, at 159 K". Acta Crystallographica Section C Crystal Structure Communications 40 (11): 1892–1894. doi:10.1107/S0108270184009963.

[8] Wang, Zhenlei; Richter, Henning; Howard, Jack B.; Jordan, Jude; Carlson, Joel; Levendis, Yiannis A. (2004-06-01). "Laboratory Investigation of the Products of the Incomplete Combustion of Waste Plastics and Techniques for Their Minimization". Industrial & Engineering Chemistry Research 43 (12): 2873–2886. doi:10.1021/ie030477u. ISSN 0888-5885. https://doi.org/10.1021/ie030477u.

[9] F. G. Bordwell (1988). "Equilibrium acidities in dimethyl sulfoxide solution". Acc. Chem. Res. 21 (12): 456–463. doi:10.1021/ar00156a004.

[scherf-10] G. W. Scherf; 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 38: 697. doi:10.1139/v60-100. .

[11] Ewen, J. A.; Jones, R. L.; Razavi, A.; Ferrara, J. D. (1988). "Syndiospecific Propylene Polymerizations with Group IVB Metallocenes". Journal of the American Chemical Society 110 (18): 6255–6256. doi:10.1021/ja00226a056. PMID 22148816.

[12] Kurdyukova, I. V.; Ishchenko, A. A. (2012). "Organic dyes based on fluorene and its derivatives". Russian Chemical Reviews 81 (3): 258–290. doi:10.1070/RC2012v081n03ABEH004211. Bibcode: 2012RuCRv..81..258K.

v t e Polycyclic aromatic hydrocarbons
2 rings	Butalene Azulene Naphthalene
3 rings	Acenaphthene Acenaphthylene Anthracene Fluorene Phenalene Phenanthrene
4 rings	Benz[a]anthracene Benzo[a]fluorene Benzo[c]fluorene Benzo[c]phenanthrene Chrysene Fluoranthene Pyrene Tetracene Triphenylene Tricyclobutabenzene
5 rings	Benz[e]acephenanthrylene Benzopyrene Benzo[a]pyrene Benzo[e]pyrene Benzo[a]fluoranthene Benzo[b]fluoranthene Benzo[j]fluoranthene Benzo[k]fluoranthene trans-Bicalicene Dibenz[a,h]anthracene Dibenz[a,j]anthracene Olympicene Pentacene Perylene Picene Tetraphenylene
6+ rings	Anthanthrene Benzo[ghi]perylene Circulene Corannulene Coronene Dicoronylene Diindenoperylene Heptacene Hexacene Kekulene Ovalene Zethrene
General classes	Acene Helicene Phenacene