Trifluoroacetyl Chloride

[354-32-5]  · C2ClF3O  · Trifluoroacetyl Chloride  · (MW 132.47)

(useful for the preparation of trifluoro ketones1,2 and for the elimination of epoxides to alkenes3)

Physical Data: bp -27 °C; mp -146 °C.

Form Supplied in: nonflammable gas supplied in metal cylinders.

Preparative Methods: can be generated in situ from Trifluoroacetic Anhydride and Lithium Chloride3 or Trifluoroacetic Acid and Phosphorus(V) Chloride.2

Handling, Storage, and Precautions: highly toxic material; handle accordingly. Use in a fume hood.

General Considerations.

Trifluoroacetyl chloride has limited use in organic synthesis due to its in situ preparation or use of the gas form. The preparation of common trifluoroacetate derivatives is achieved by the action of trifluoroacetic anhydride with the corresponding alcohol or amine.

Trifluoroacetyl chloride has been used to effect the elimination of epoxides to the corresponding alkene. The intermediate chlorohydrin trifluoroacetate must be treated with iodide to achieve elimination (eq 1).

In practice, the conversion of an alkene from one geometry to the other can be realized via epoxidation and then treatment with trifluoroacetyl chloride followed by Sodium Iodide.

Trifluoroacetophenone2 is prepared by the action of trifluoroacetyl chloride on benzene in the presence of Aluminum Chloride (eq 2).

Trifluoroacetyl chloride reacts with N,O-Dimethylhydroxylamine hydrochloride in the presence of Triethylamine to form N-methoxy-N-methyltrifluoroacetamide (eq 3).1,4 This interesting reagent reacts with Grignard reagents to form trifluoro ketones (eq 4).

Trifluoroacetyl chloride is used to acylate an ylide which leads to a,a,a-trifluoro-b-keto esters (eq 5).5

Related Reagents.

Trifluoroacetic Anhydride.

1. Shaw, D. A.; Tuominen, T. C. TL 1985, 15, 1291.
2. Hull, W. E.; Seeholzer, K.; Baumeister, M.; Ugi, I. T 1986, 42, 547.
3. Sonnet, P. E. JOC 1980, 45, 154.
4. Nahm, S.; Weinreb, S. M. TL 1981, 22, 3815.
5. Jeong, I. H.; Burton, D. J.; Cox, D. G. TL 1986, 27, 3709. Thenappan, A.; Burton, D. J. TL 1989, 30, 6113; JOC 1991, 56, 273.

Regina Zibuck

Wayne State University, Detroit, MI, USA

Copyright 1995-2000 by John Wiley & Sons, Ltd. All rights reserved.