Chlorotrifluoroethylene

[79-38-9]  · C2ClF3  · Chlorotrifluoroethylene  · (MW 116.47)

(addition reactions; cycloadditions; trifluorovinylations)

Physical Data: mp -158 °C; bp -28.4 °C.

Solubility: sol organic solvents (ether, THF).

Form Supplied in: flammable gas, inhibited with 1% Bu3N.

Handling, Storage, and Precautions: inhalation toxicity LC50: 1000 ppm; flammable; use in a fume hood.

Addition Reactions.

Chlorotrifluoroethylene is a starting material for the preparation of fluorinated molecules, via addition or addition-elimination reactions, the regioselectivity of which is not always, but can be, excellent. Halogenation according to eq 1 is a good example.1 Hydrobromination under UV irradiation also gives a unique pentahaloethane (eq 2).2

Lewis acid catalyzed addition of CCl4 proceeds via addition-substitution (eq 3).3

The nucleophilic addition of alcohols,4 thiols,5 and primary and secondary amines6 in the presence of base occurs readily; the regioselectivity corresponds to a better stabilization of the negative charge by -CFCl, than by -CF2 (eqs 4 and 5). With diethanolamine,7 further substitution occurs (eq 6).

Various organometallic reagents8-11 follow the addition-elimination pattern (eqs 7-9), as do lithium amides (eq 10).

Thiolates and alcoholates follow the same scheme. Allylates represent an interesting case since the initially formed allyl fluorovinyl ether undergoes a fluorine accelerated Claisen rearrangement, even at -35 °C (eq 11).12

Cycloadditions.

Insertion of difluorocarbene generates chloropentafluorocyclopropane (eq 12).13

Various cycloadditions are observed at high temperatures (pressure vessel) with alkenes, alkynes, and conjugated dienes ([2 + 2] addition prevails largely over [4 + 2]) (eqs 13-15).14-16

Trifluorovinylations.

A useful synthon for the nucleophilic introduction of the trifluorovinyl moiety is obtained by chlorine/lithium exchange (eq 16).17

The vinyllithium species must be handled at low temperatures. It reacts with aldehydes or ketones to give trifluorovinylcarbinols, which are a source of a-fluoro-a-ethylenic acids (by acidic treatment). They are also a source of a,b-difluoro-a-ethylenic alcohols if a lithium reagent is added, in a second step, to the reaction mixture (eq 17).18

The analogous zinc derivative19 is much more thermally stable, and can be vinylated, arylated, or acylated by a palladium catalyzed reaction with vinyl or aryl halides, or with acyl chlorides (eq 18).18

The analogs CF2=CFBr and CF2=CFI have been used in several similar reactions, but they are more expensive. However, when treated with Zinc powder, they deliver the corresponding zinc derivative.20


1. Hauptschein, M.; Braid, M.; Fainberg, A. M. JACS 1961, 83, 2495.
2. Haszeldine, R. N.; Steele, B. R. JCS 1954, 3747.
3. Posta, A.; Paleta, O. CCC 1966, 31, 2389.
4. (a) Tarrant, P.; Brown, H. C. JACS 1951, 73, 1781. (b) Lichtenberger, J.; Geyer, A. M. BSF(2) 1957, 581 and references cited therein.
5. Terrell, R. C.; Ucciardi, T.; Vitcha, J. F. JOC 1965, 30, 4011.
6. Sterlin, R. N.; Bogachev, V. E.; Yatsenko, R. D.; Knunyants, I. L. IZV 1959, 2151 (CA 1960, 54, 10 848h).
7. Martini, T. TL 1972, 3957.
8. Sauvêtre, R.; Normant, J. F. BSF(2) 1972, 3202.
9. Dixon, S. JOC 1956, 21, 400.
10. Tarrant, P.; Savory, J.; Iglehart, E. S. JOC 1964, 29, 2009.
11. Yakubovich, A. Ya.; Sergeev, A. P.; Belyaeva, I. N. DOK 1965, 161, 1362 (CA 1965, 63, 6967d).
12. Normant, J. F.; Reboul, O.; Sauvêtre, R.; Deshayes, H.; Masure, D.; Villieras, J. BSF(2) 1974, 2072.
13. Mitsch, R. A. JHC 1964, 1, 271.
14. Tarrant, P.; Johnson Jr., R. W.; Brey Jr., W. S. JOC 1962, 27, 602.
15. Roberts, J. D.; Sharts, C. M. OR 1962, 12, 1.
16. Park, J. D.; Holler, H. V.; Lacher, J. R. JOC 1960, 25, 990.
17. Normant, J. F.; Foulon, J. P.; Masure, D.; Sauvêtre, R.; Villieras, J. S 1975, 122.
18. Normant, J. F. JOM 1990, 400, 19.
19. Gillet, J. P.; Sauvêtre, R.; Normant, J. F. S 1986, 355.
20. Heinze, P. L.; Burton, D. J. JFC 1986, 31, 115.

Raymond Sauvêtre & Jean F. Normant

Université Pierre et Marie Curie, Paris, France



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