Hexafluoroacetone

Chemical compound From Wikipedia, the free encyclopedia

Hexafluoroacetone (HFA) is a chemical compound with the formula (CF3)2CO. It is structurally similar to acetone; however, its reactivity is markedly different. It is a colourless, hygroscopic, nonflammable, highly reactive gas characterized by a musty odour.[2] According to electron diffraction, HFA and acetone adopt very similar structures, the C-O distance being only longer in the fluorinated compound (124.6 vs 121.0 pm), possibly due to steric effects.[3]

Quick facts Names, Identifiers ...
Hexafluoroacetone
Hexafluoropropanone skeletal structure
Hexafluoropropanone skeletal structure
Hexafluoropropanone 3D structure
Hexafluoropropanone 3D structure
Names
Preferred IUPAC name
1,1,1,3,3,3-Hexafluoropropan-2-one
Other names
perfluoroacetone
acetone hexafluoride
perfluoro-2-propanone
Identifiers
3D model (JSmol)
ChEBI
ChemSpider
ECHA InfoCard 100.010.616 Edit this at Wikidata
EC Number
  • 211-676-3
RTECS number
  • UC2450000
UNII
UN number 2420
  • InChI=1S/C3F6O/c4-2(5,6)1(10)3(7,8)9 checkY
    Key: VBZWSGALLODQNC-UHFFFAOYSA-N checkY
  • InChI=1/C3F6O/c4-2(5,6)1(10)3(7,8)9
    Key: VBZWSGALLODQNC-UHFFFAOYAI
  • FC(F)(F)C(=O)C(F)(F)F
Properties
C3F6O
Molar mass 166.02 g/mol
Appearance Colorless gas
Odor musty[1]
Density 1.32 g/ml, liquid
Melting point −129 °C (144 K)
Boiling point −28 °C (245 K)
Reacts with water
Vapor pressure 5.8 atm (20 °C)[1]
Hazards
Occupational safety and health (OHS/OSH):
Main hazards
 Toxic (T),
Corrosive (C)
GHS labelling:
GHS05: CorrosiveGHS06: ToxicGHS07: Exclamation markGHS08: Health hazard
Danger
H301, H310, H311, H314, H315, H330, H360, H370, H372
P201, P202, P260, P262, P264, P270, P271, P280, P281, P284, P301+P310, P301+P330+P331, P302+P350, P302+P352, P303+P361+P353, P304+P340, P305+P351+P338, P307+P311, P308+P313, P310, P312, P314, P320, P321, P330, P332+P313, P361, P362, P363, P403+P233, P405, P410+P403, P501
NFPA 704 (fire diamond)
NFPA 704 four-colored diamondHealth 3: Short exposure could cause serious temporary or residual injury. E.g. chlorine gasFlammability 0: Will not burn. E.g. waterInstability 2: Undergoes violent chemical change at elevated temperatures and pressures, reacts violently with water, or may form explosive mixtures with water. E.g. white phosphorusSpecial hazard W: Reacts with water in an unusual or dangerous manner. E.g. sodium, sulfuric acid
3
0
2
W
Flash point Nonflammable[1]
NIOSH (US health exposure limits):
PEL (Permissible)
 none[1]
REL (Recommended)
 TWA 0.1 ppm (0.7 mg/m3) [skin][1]
IDLH (Immediate danger)
 N.D.[1]
Related compounds
Related ketones;
organofluorides
 Acetone;
Hexafluoro-2-propanol
Except where otherwise noted, data are given for materials in their standard state (at 25 Â°C [77 Â°F], 100 kPa).
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The term "hexafluoroacetone" can refer to the sesquihydrate (1.5 H2O), which is a hemihydrate of hexafluoropropane-2,2-diol (F
3C)
2C(OH)
2, a geminal diol. Hydrated HFA behaves differently from the anhydrous material.

Synthesis

The industrial route to HFA involves treatment of hexachloroacetone with HF:[4]

(CCl3)2CO + 6 HF → (CF3)2CO + 6 HCl

Laboratory methods

Hydrated HFA can be converted to HFA by treatment with hot sulfuric acid.[5]

It has also be prepared from hexafluoropropylene oxide, which will rearrange to give HFA when heated in the presence of a Lewis acid such as AlCl3.[6] The Lewis acid catalysed oxidation of hexafluoropropylene will also produce HFA, via a similar mechanism.

Although it is commercially available, HFA can be prepared on the laboratory-scale from hexafluoropropylene.[7] In the first step KF catalyzes the reaction of the alkene with elemental sulfur to give the 1,3-dithietane dimer of hexafluorothioacetone. This species is then oxidized by potassium iodate to give HFA.[8]

Uses

Hexafluoroacetone is used in the production of hexafluoroisopropanol:

(CF3)2CO + H2 → (CF3)2CHOH

It is also used as a precursor to hexafluoroisobutylene,[4] a monomer used in polymer chemistry, and as a building block in the synthesis of midaflur, bisphenol AF, 4,4′-(hexafluoroisopropylidene)diphthalic anhydride, and alitame.

Reactivity

Hexafluoroacetone imine is an unusual primary ketimine that is isolable.
Ammonia adduct of hexafluoroacetone

With water, hexafluoroacetone converts to the hydrate. The equilibrium constant (Keq) for the formation of this geminal diol is 106 M−1. The analogous equilibrium for acetone is an unfavorable 10−3 M−1.[9] Hexafluoroacetone-hydrates are acidic. In an analogous reaction, ammonia adds to hexafluoroacetone to give the hemiaminal (CF3)2C(OH)(NH2) which can be dehydrated with phosphoryl chloride to give the imine (CF3)2CNH.[10]

Nucleophiles attack occurs at the carbonyl carbon of hexafluoroacetone, as illustrated above. Thus, HFA readily forms lactones when treated with hydroxy- and amine-substituted carboxylic acids. In such reactions, HFA serves both as electrophile and dehydrating agent:[5]

RCH(OH)CO2H + O=C(CF3)2 → RCH(O)CO2C(CF3)2 + (HO)2C(CF3)2

See also

References

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