Hexafluoroacetone

Hexafluoroacetone (HFA) is a chemical compound with the formula (CF3)2CO. It is structurally similar to acetone; however, its reactivity is markedly different. It a colourless, hygroscopic, nonflammable, highly reactive gas characterized by a musty odour.[2] The most common form of this substance is hexafluoroacetone sesquihydrate (1.5 H2O), which is a hemihydrate of hexafluoropropane-2,2-diol (F
3C)
2C(OH)
2, a geminal diol .

Hexafluoroacetone
Names
IUPAC name
1,1,1,3,3,3-hexafluoro-2-propanone
Other names
perfluoroacetone
acetone hexafluoride
perfluoro-2-propanone
Identifiers
3D model (JSmol)
ChEBI
ChemSpider
ECHA InfoCard 100.010.616
EC Number
  • 211-676-3
RTECS number
  • UC2450000
UNII
UN number 2420
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
Main hazards Toxic (T),
Corrosive (C)
GHS pictograms
GHS Signal word Danger
GHS hazard statements
 H280, H301, H310, H311, H314, H315, H318, H330, H360, H370, H372
P201, P202, P260, P262, P264, P270, P271, P280, P281, P284, P301+310, P301+330+331, P302+350, P302+352, P303+361+353, P304+340, P305+351+338, P307+311, P308+313, P310, P312, P314, P320, P321, P322
NFPA 704 (fire diamond)
Flammability code 0: Will not burn. E.g. waterHealth code 3: Short exposure could cause serious temporary or residual injury. E.g. chlorine gasReactivity code 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
0
3
2
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 °C [77 °F], 100 kPa).
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Infobox references

Synthesis

The industrial route to HFA involves treatment of hexachloroacetone with HF:[3]

(CCl3)2CO + 6 HF → (CF3)2CO + 6 HCl

Hexafluoropropylene oxide rearranges to give HFA.

In the laboratory, HFA can be prepared in a two step process from perfluoropropene. In the first step KF catalyzes the reaction of the alkene with elemental sulfur to give the 1,3-dithietane [(CF3)2CS]2. This species is then oxidized by iodate to give (CF3)2CO.[4]

Uses

Hexafluoroacetone is used in the production of hexafluoroisopropanol:

(CF3)2CO + H2 → (CF3)2CHOH

It is also used as a precursor to hexafluoroisobutylene,[3] 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 is an electrophile. Nucleophiles attack at the carbonyl carbon. In water, hexafluoroacetone predominantly exists as 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.[5] 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.[6]

Hexafluoroacetone imine is an unusual primary ketimine that is stable.
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See also

References
  1. NIOSH Pocket Guide to Chemical Hazards. "#0319". National Institute for Occupational Safety and Health (NIOSH).
  2. CDC - NIOSH Pocket Guide to Chemical Hazards
  3. Günter Siegemund, Werner Schwertfeger, Andrew Feiring, Bruce Smart, Fred Behr, Herward Vogel, Blaine McKusick (2002). "Fluorine Compounds, Organic". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/14356007.a11_349.CS1 maint: uses authors parameter (link)
  4. Van Der Puy, M. ; Anello, L. G. (1990). "Hexafluoroacetone". Organic Syntheses.CS1 maint: multiple names: authors list (link); Collective Volume, 7, p. 251
  5. Lemal, David M. (2004). "Perspective on Fluorocarbon Chemistry". The Journal of Organic Chemistry. 69 (1): 1–11. doi:10.1021/jo0302556. PMID 14703372.
  6. W. J. Middleton, H. D. Carlson (1970). "Hexafluoroacetone imine". Org. Syntheses. 50: 81–3. doi:10.15227/orgsyn.050.0081..
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