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Fluorene

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Title: Fluorene  
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Subject: Polycyclic aromatic hydrocarbon, Polyfluorene, Naphthalene, Fluorone, F number (chemistry)
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Fluorene

Fluorene[1]
Names
IUPAC name
9H-Fluorene
Identifiers
 Y
ChEBI  Y
ChEMBL  Y
ChemSpider  Y
EC number 201-695-5
Jmol-3D images Image
KEGG  Y
PubChem
RTECS number LL5670000
UNII  Y
Properties
C13H10
Molar mass 166.223 g/mol
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
Hazards
Safety data sheet Sigma-Aldrich
NFPA 704
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).
 Y  (: Y/N?)

Fluorene , 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.[2] It is insoluble in water and soluble in many organic solvents.

Contents

  • Synthesis, structure, and reactivity 1
    • Acidity 1.1
  • Uses 2
  • See also 3
  • References 4
  • External links 5

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, 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.[7]

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]

organic light-emitting diodes.

See also

References

  1. ^ Merck Index, 11th Edition, 4081
  2. ^ a b c 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
  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. ^ 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
  6. ^ F. G. Bordwell (1988). "Equilibrium acidities in dimethyl sulfoxide solution". Acc. Chem. Res. 21 (12): 456–463.  
  7. ^ 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.
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