Chloroacetyl Fluoride

[359-14-8]  · C2H2ClFO  · Chloroacetyl Fluoride  · (MW 96.49)

(acylating agent; a precursor to chloroacetylium ion)

Physical Data: bp 73-75 °C; d20 1.379 g cm-3.1

Preparative Methods: generally prepared by fluorination of ClCH2COCl.1 A variety of reagents has been employed for this transformation, including benzoyl fluoride/KH2F,2a KHF2,2b KF,2c KF/tetraalkylammonium chloride,2d and dialkylaminosulfur trifluoride.2e Preparation of ClCH2COF may also be accomplished from ClCH2CO2H through the use of 2-chloro-1,1,2-trifluoroethyldiethylamine as the fluoride source.3 Treatment of ClCH2CF2CF2OCH3 with SO3 leads to the formation of ClCH2COF in 94% yield, which is the highest yield reported for the preparation of the reagent.4

Handling, Storage, and Precautions: is corrosive, moisture sensitive, and should be stored under anhydrous conditions. This reagent should be handled in a fume hood.

Chloroacetyl fluoride is less well studied compared to its analog Chloroacetyl Chloride. The majority of the publications concerning ClCH2COF are centered on its structure and spectroscopic properties.5 Regarding synthetic chemistry aspects, ClCH2COCl has mainly been used as an acylating agent. When ClCH2COF was treated with SbF5 in SO2 solution at low temperature, chloroacetylium ion was observed.6a Its stable hexafluoroantimonate salt has been isolated (eq 1) and used as chloroacylating agent for aromatic compounds (eq 2).6b Chloroacetylium hexafluoroantimonate reacts with benzene, toluene, p-xylene, and mesitylene to generate the corresponding chloroacylated products in high yields. In the case of toluene, a 7.7:3.4:88.9 isomer distribution ratio was obtained for the ortho, meta, and para isomers.

Reaction between ClCH2COF and diazomethane led to formation of ClCH2COCHN2, which was in situ converted to a-chloro-a-fluoroacetone in 32% yield by the addition of HF (eq 3).7

It was also reported that ClCH2COF can be electrochemically transformed into chlorofluoroacetic acids.8

Related Reagents.

Chloroacetyl Chloride.

1. Redemann, C. E.; Chaikin, S. W.; Fearing, R. B.; Rotariu, G. J.; Savit, J.; Hoesen, D. V. JACS 1948, 70, 3604.
2. (a) Olah, G.; Kuhn, S.; Beke, S. CB 1956, 89, 862. (b) Kitano, T.; Fukui, K. J. Chem. Soc. Jpn., Ind. Chem. Sect. 1955, 58, 453. (c) Saunders, S. JCS 1948, 1773. (d) Tordeux, M.; Wakselman, C. SC 1982, 12, 513. (e) Markovski, L. N.; Pashinnik, V. E. S 1975, 801.
3. Schaumburg, K. JMR 1972, 7, 177.
4. Belaventsev, M. A.; Luk'yanov, V. B.; Ragulin, L. I.; Sokol'Skii, G. A. JOU 1971, 7, 720.
5. For example, see: (a) Lund, A.; Stoelevik, R. J. Mol. Struct. 1990, 221, 95. (b) Little, T. S.; Wang, A. Y.; Durig, J. R. J. Mol. Struct. 1990, 217, 221.
6. (a) Olah, G. A.; Germain, A.; Lin, H. C.; JACS 1975, 97, 5481. (b) Olah, G. A.; Lin, H. C.; Germain, A. S 1974, 895.
7. Olah, G.; Kuhn, S. CB 1956, 89, 864.
8. (a) Dvorak, F.; Dedek, V. CCC 1966, 31, 2727. (b) Dvorak, F.; Dedek, V. CCC 1968, 33, 3913.

George A. Olah, G. K. Surya Prakash, Qi Wang, & Xing-ya Li

University of Southern California, Los Angeles, CA, USA

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