Fluorene

Source: Wikipedia, the free encyclopedia.
Not to be confused with Fluorane, Fluorine, Fluorone, or Fluorenone.
Fluorene[1]
Names
Preferred IUPAC name
9H-Fluorene[2]
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 Edit this at Wikidata
EC Number
  • 201-695-5
KEGG
RTECS number
  • LL5670000
UNII
  • InChI=1S/C13H10/c1-3-7-12-10(5-1)9-11-6-2-4-8-13(11)12/h1-8H,9H2 checkY
    Key: NIHNNTQXNPWCJQ-UHFFFAOYSA-N checkY
  • 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
  • c1ccc2c3ccccc3Cc2c1
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 organic solvents
log P 4.18
Acidity (pKa) 22.6
-110.5·10−6 cm3/mol
Hazards
NFPA 704 (fire diamond)
NFPA 704 four-colored diamondHealth 1: Exposure would cause irritation but only minor residual injury. E.g. turpentineFlammability 1: Must be pre-heated before ignition can occur. Flash point over 93 °C (200 °F). E.g. canola oilInstability 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)
Safety data sheet (SDS) Sigma-Aldrich
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
checkY verify (what is checkY☒N ?)

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.[citation needed] 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 (

pKa = 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

dioxane.[10]

Ligand properties

Fluorene and its derivatives can be deprotonated to give

cyclopentadienide
.

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

9-Fluorenylmethyl chloroformate (Fmoc chloride) is used to introduce the 9-fluorenylmethyl carbamate (Fmoc) protecting group on amines in peptide synthesis.[3]

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]

See also

References

  1. ^ Merck Index, 11th Edition, 4081
  2. ISBN 978-0-85404-182-4
    .
  3. ^
    ISBN 978-3527306732
    .
  4. doi:10.1002/cber.18730060169
  5. ISSN 0040-4039
    .
  6. doi:10.1038/173635a0
  7. doi:10.1107/S0108270184009963
    .
  8. ISSN 0888-5885
    .
  9. doi:10.1021/ar00156a004
    .
  10. doi:10.1139/v60-100
    ..
  11. PMID 22148816
    .
  12. S2CID 95312830
    .

External links

  • Fluorene in the National Institute of Standards and Technology database.
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