Bromine Trifluoride1

BrF3

[7787-71-5]  · BrF3  · Bromine Trifluoride  · (MW 136.90)

(forms in situ bromine monofluoride,2 oxidative fluorination on heteroatoms3 and polyfluoroaromatics,4 substituting aliphatic halogens5 and tertiary hydrogens with fluorine,6 brominating aromatic rings,7 converting carbonyls through their azines and thioesters8 to the CF2 group)

Physical Data: mp 8.8 °C; bp 126 °C; dliq 2.49 g cm-3.

Form Supplied in: commercially supplied in cylinders as a volatile liquid, pale yellow when pure; orange-red crystals at low temperatures; dec at high temperature to Br2 and BrF5.9

Handling, Storage, and Precautions: use in a fume hood; BrF3 can be stored in stainless steel or Teflon containers. It reacts violently with water and many oxygen-containing organic solvents.

Introduction.

The organic chemistry associated with BrF3 is still in its infancy. The high reactivity of the reagent is one of the reasons that, until recently, its chemistry was not strongly developed. However, its commercial availability and the ease of preparation from the corresponding elements are changing this situation.

Bromofluorination of Alkenes.

When BrF3 is mixed with bromine, the active species is Bromine Monofluoride, which can be added to alkenes (eq 1)2 or can brominate deactivated aromatic rings (eq 2).7 Martin used BrF3 to prepare compounds with hypervalent heteroatoms, many of them unattainable otherwise (eq 3).3 A key step in Lemal's unique synthesis of perfluorocyclopentadiene also involved an oxidative fluorination (eq 4).4 BrF3 is capable of electrophilic fluorination and it can substitute halogens, as well as unactivated tertiary hydrogens whose bond with carbon is relatively electron rich (eqs 5 and 6).5,6

Recently, bromine trifluoride found promising use as a tool for converting carbonyls to the important CF2 group. Aldehydes and ketones are converted through their easy-to-make azines (eq 7), while esters give the corresponding thioesters to form eventually a-fluoromethylene ethers (eq 8).8


1. Boguslavskaya, L. S.; Chuvatkin, N. N. In New Fluorinating Agents in Organic Synthesis; German, L.; Zemkov, S., Eds.; Springer: Berlin, 1989.
2. Boguslavskaya, L. S.; Chuvatkin, N. N.; Kartashov, A. V.; Ternovskoi, L. A. JOU 1987, 23, 230.
3. (a) Michalak, R. S.; Wilson, S. R.; Martin, J. C. JACS 1984, 106, 7529; (b) Michalak, R. S.; Martin, J. C. JACS 1982, 104, 1683.
4. Soelch, R. R.; Mauer, G. W.; Lemal, D. M. JOC 1985, 50, 5845.
5. Kartashov, A. V.; Chuvatkin, N. N.; Boguslavskaya, L. S. JOU 1988, 24, 2276.
6. Boguslavskaya, L. S.; Kartashov, A. V.; Chuvatkin, N. N. JOU 1989, 25, 1835.
7. Rozen, S.; Lerman, O. JOC 1993, 58, 239.
8. (a) Rozen, S.; Mishani, E. CC 1993, 1761. (b) Rozen, S.; Mishani, E.; Baz-Haim, A. JOC 1994, 59, 2918.
9. Stein, L. JACS 1959, 81, 1273.

Shlomo Rozen

Tel Aviv University, Israel



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