Fluorene

Fluorene /ˈflʊərn/, 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.[2] 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. Instead it is a weak acid.

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
3D model (JSmol)
ChEBI
ChEMBL
ChemSpider
ECHA InfoCard 100.001.541
EC Number
  • 201-695-5
KEGG
RTECS number
  • LL5670000
UNII
Properties
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)
1.992 mg/L
Solubility soluble in CS2, ether, benzene, hot alcohol, pyrimidine, CCl4, toluene, acetone, DMSO
log P 4.18
Acidity (pKa) 22.6
-110.5·10−6 cm3/mol
Hazards
Safety data sheet Sigma-Aldrich
NFPA 704 (fire diamond)
Flammability code 1: Must be pre-heated before ignition can occur. Flash point over 93 °C (200 °F). E.g. canola oilHealth code 1: Exposure would cause irritation but only minor residual injury. E.g. turpentineReactivity code 0: Normally stable, even under fire exposure conditions, and is not reactive with water. E.g. liquid nitrogenSpecial hazards (white): no code
1
1
0
Flash point 152 °C (306 °F; 425 K)
Lethal dose or concentration (LD, LC):
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).
Y verify (what is YN ?)
Infobox references

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 fluorenone with zinc.[3] The fluorene molecule is nearly planar,[4] although each of the two benzene rings is coplanar with the central carbon 9.[5]

Acidity

The C9-H sites of the fluorene ring are weakly acidic (pKa = 22.6 in DMSO.[6]) 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.[7]

Ligand properties

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

A fluorenyl-derived precatalyst featuring for producing syndiotactic polypropylene.[8]

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.[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 as a luminophore in organic light-emitting diodes.

Med compounds

Cicloprofen is a NSAID 2-arylpropionic acid made from fluorene.

A really old design for a TCA is 9-[b-Diethylaminoethyl]-fluorene (pg 1439).[9]This actually predates designs such as imipramine. {This exact agent is better identified as one of the fenpiprane analogs, and appears in the same patent.} Carbazole was also used in the same literature entry.

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.[10]

gollark: No, they're just bad.
gollark: That's not really very acronym-y. They generally just remove boring words like "he" or "or".
gollark: Could you use this for pangram generation? That might be cool.
gollark: I see.
gollark: Doesn't that mean that your thing might end up seeing some data twice? Unless you shuffle it once and split it into chunks or something.

See also

References

  1. Merck Index, 11th Edition, 4081
  2. Griesbaum, Karl; Behr, Arno; Biedenkapp, Dieter; Voges, Heinz-Werner; Garbe, Dorothea; Paetz, Christian; Collin, Gerd; Mayer, Dieter; Höke (2000). "Hydrocarbons". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/14356007.a13_227.
  3. Fittig, Rud. (1873), "Ueber einen neuen Kohlenwasserstoff aus dem Diphenylenketon" Ber. Dtsch. Chem. Ges. volume 6, p. 187.doi:10.1002/cber.18730060169
  4. D. M. Burns, John Iball (1954), Molecular Structure of Fluorene Nature volume 173, p. 635. doi:10.1038/173635a0
  5. 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.
  6. F. G. Bordwell (1988). "Equilibrium acidities in dimethyl sulfoxide solution". Acc. Chem. Res. 21 (12): 456–463. doi:10.1021/ar00156a004.
  7. 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..
  8. 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.
  9. Eisleb, Otto (1941). "Neue Synthesen mittels Natriumamids". Berichte der Deutschen Chemischen Gesellschaft (A and B Series). 74 (8): 1433–1450. doi:10.1002/cber.19410740814. ISSN 0365-9488.
  10. Kurdyukova, I. V.; Ishchenko, A. A. (2012). "Organic dyes based on fluorene and its derivatives". Russian Chemical Reviews. 81 (3): 258–290. Bibcode:2012RuCRv..81..258K. doi:10.1070/RC2012v081n03ABEH004211.CS1 maint: uses authors parameter (link)
  • Fluorene in the National Institute of Standards and Technology database.
This article is issued from Wikipedia. The text is licensed under Creative Commons - Attribution - Sharealike. Additional terms may apply for the media files.