Trifluoroacetone - an Organofluorine Compound

Trifluoroacetone [CF₃C(O)CH₃] is an organofluorine compound with the formula CF3C(O)CH3. The compound is a colorless liquid with an odor similar to chloroform.

Keep away from ignition sources and use explosion-proof equipment. Keep the container tightly closed in a well-ventilated, dry fume hood. It is advised to store at 2–8°C. Over time, pressure can build up, causing containers to burst.

Properties

Trifluoroacetone exhibits reactivities not normally seen in common ketones. Aside from influencing physical properties, the trifluoromethyl group increases the electrophilicity of the carbonyl center. As with formaldehyde, its hydration equilibrium is primarily on the side of the geminal diol in an aqueous solution.

Melting point: -78 °C
Boiling point: 22 °C(lit.)
Density: 1.252 g/mL at 25 °C(lit.)
Vapor pressure: 13.62 psi ( 20 °C)
Flash point: −23 °F
Storage temp.: 2-8°C
Form: Liquid
Color: Clear colorless
Water Solubility: Miscible

Preparation and reactions

It can be synthesized in a variety of ways. The compound was first synthesized by decarboxylating ethyl 4,4,4-trifluoro-3-oxobutanoate (CF₃COCH₂CO₂Et). It has been reported that by treating trifluoroacetic acid (CF₃CO₂H) with an excess of methylmagnesium iodide, 56 percent yield of -trifluoroacetone (CF₃COCH₃) can be obtained (MeMgI, 3 equiv).

CF₃COCH₃ was obtained in 86 percent yield through the reaction of TMSCF₃ and ethyl acetate in the presence of cesium fluoride using the Ruppert–Prakash reagent (TMSCF₃) (CsF). In addition to the methods described above, CF₃COCH₃ was obtained in a low yield via a Cu(I)-catalyzed reaction of sodium trifluoroacetate (CF3CO₂Na) and acetyl chloride (CH₃COCl).

Trifluoroacetone is produced by decarboxylation of trifluoroacetoacetic acid:

CF3C(O)CH2CO2H → CF3C(O)CH3 + CO2

The acetoacetic acid in turn is obtained via condensation of acetate and trifluoroacetate esters.

Trifluoroacetone has been examined as an oxidizing agent in Oppenauer oxidation, in which case hydroxyl groups of secondary alcohols can be oxidized in the presence of hydroxy groups of primary alcohols.

Uses

Starting with 2,6-dihalopyridines, trifluoracetone is used in the synthesis of 2-trifluoromethyl-7-azaindoles. By using a Strecker reaction followed by either nitrile hydrolysis or reduction, the derived chiral imine is used to prepare enantiopure -trifluoromethyl alanines and diamines.

Precautions