Hexafluoroacetone (HFA) is a

chemical compound A chemical compound is a chemical substance composed of many identical molecules (or molecular entities) containing atoms from more than one chemical element held together by chemical bonds. A molecule consisting of atoms of only one element ...

with the formula (CF₃)₂CO. It is structurally similar to

acetone Acetone (2-propanone or dimethyl ketone), is an organic compound with the formula . It is the simplest and smallest ketone (). It is a colorless, highly volatile and flammable liquid with a characteristic pungent odour. Acetone is miscib ...

; however, its reactivity is markedly different. It a colourless, hygroscopic, nonflammable, highly reactive gas characterized by a musty odour. The most common form of this substance is hexafluoroacetone sesquihydrate (1.5 H₂O), which is a

hemihydrate In chemistry, a hemihydrate (or semihydrate) is a hydrate whose solid contains one molecule of water of crystallization per two other molecules, or per two unit cell In geometry, biology, mineralogy and solid state physics, a unit cell is ...

of hexafluoropropane-2,2-diol , a

geminal diol In chemistry, the descriptor geminal () refers to the relationship between two atoms or functional groups that are attached to the same atom. A geminal diol, for example, is a diol (a molecule that has two alcohol functional groups) attached t ...

Synthesis

The industrial route to HFA involves treatment of

hexachloroacetone Hexachloroacetone is an organic compound with the formula (Cl3C)2CO. It is also called hexachloropropanone or perchloroacetone. Numbers indicating the position of the chlorine-atoms are generally omitted as all the possible positions are substitut ...

with HF: :(CCl₃)₂CO + 6 HF → (CF₃)₂CO + 6 HCl

Hexafluoropropylene oxide Hexafluoropropylene oxide (HFPO) is an intermediate used in industrial organofluorine chemistry; specifically it is a monomer for fluoropolymers. This colourless gas is the epoxide of hexafluoropropylene, that is fluorinated analog of propylene ...

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)₂CSsub>2. This species is then oxidized by iodate to give (CF₃)₂CO.

Uses

Hexafluoroacetone is used in the production of

hexafluoroisopropanol Hexafluoroisopropanol, commonly abbreviated HFIP, is the organic compound with the formula (CF3)2CHOH. This fluoroalcohol finds use as solvent and synthetic intermediate. It appears as a colorless, volatile liquid that is characterized by a stro ...

: :(CF₃)₂CO + H₂ → (CF₃)₂CHOH It is also used as a precursor to hexafluoroisobutylene, a monomer used in polymer chemistry, and as a building block in the synthesis of

midaflur Midaflur ( INN; EXP 338) is an extremely stable 3-imidazoline derivative with central skeletal muscle relaxant and sedative properties in humans and other species of mammals, exhibiting consistently high oral bioavailability and a long duration ...

, bisphenol AF, 4,4′-(hexafluoroisopropylidene)diphthalic anhydride, and

alitame Alitame is an aspartic acid-containing dipeptide sweetener. It was developed by Pfizer in the early 1980s and currently marketed in some countries under the brand name Aclame. Most dipeptides are not sweet, but the unexpected discovery of aspart ...

Reactivity

Hexafluoroacetone is an

electrophile In chemistry, an electrophile is a chemical species that forms bonds with nucleophiles by accepting an electron pair. Because electrophiles accept electrons, they are Lewis acids. Most electrophiles are positively charged, have an atom that carrie ...

. Nucleophiles attack at the

carbonyl In organic chemistry, a carbonyl group is a functional group composed of a carbon atom double-bonded to an oxygen atom: C=O. It is common to several classes of organic compounds, as part of many larger functional groups. A compound containi ...

carbon. In water, hexafluoroacetone predominantly exists as the hydrate. The

equilibrium constant The equilibrium constant of a chemical reaction is the value of its reaction quotient at chemical equilibrium, a state approached by a dynamic chemical system after sufficient time has elapsed at which its composition has no measurable tendency ...

(K_eq) for the formation of this

is 10⁶ M⁻¹. The analogous equilibrium for acetone is an unfavorable 10⁻³ M⁻¹. Hexafluoroacetone-hydrates are acidic. In an analogous reaction,

ammonia Ammonia is an inorganic compound of nitrogen and hydrogen with the formula . A stable binary hydride, and the simplest pnictogen hydride, ammonia is a colourless gas with a distinct pungent smell. Biologically, it is a common nitrogenous wa ...

adds to hexafluoroacetone to give the

hemiaminal In organic chemistry, a hemiaminal (also carbinolamine) is a functional group or type of chemical compound that has a hydroxyl group and an amine attached to the same carbon atom: . R can be hydrogen or an alkyl group. Hemiaminals are intermedia ...

(CF₃)₂C(OH)(NH₂) which can be dehydrated with

phosphoryl chloride Phosphoryl chloride (commonly called phosphorus oxychloride) is a colourless liquid with the formula . It hydrolyses in moist air releasing phosphoric acid and fumes of hydrogen chloride. It is manufactured industrially on a large scale from phos ...

to give the

imine In organic chemistry, an imine ( or ) is a functional group or organic compound containing a carbon–nitrogen double bond (). The nitrogen atom can be attached to a hydrogen or an organic group (R). The carbon atom has two additional single bon ...

(CF₃)₂CNH.. Hexafluoroacetone imine

References

{{Reflist Trifluoromethyl compounds Ketones Perfluorinated compounds Trifluoromethyl ketones

Synthesis

Uses

Reactivity

See also

References