[7783-39-3] · F2Hg · Mercury(II) Fluoride · (MW 238.59)
Alternate Name: mercuric fluoride.
Physical Data: mp 645 °C, bp >650 °C, d 8.95 g cm-3.
Solubility: hydrolyzes in water; slightly sol MeCN, DMSO.
Form Supplied in: white powder.
Handling, Storage, and Precautions: turns yellow on exposure to moist air; highly toxic.
Mercury(II) fluoride has been used to replace chlorine,2 bromine,3 and iodine4 at sp3 carbon with fluorine, as shown in eqs 1-3. In cases where a typical SN2 reaction occurs, Potassium Fluoride in the presence of 18-Crown-6 is a better reagent. However, for highly halogenated compounds,5 HgF2 is the reagent of choice.
Alkenes treated with an electrophile in the presence of mercury(II) fluoride add the electrophile and fluoride to give the trans product stereoselectively, as shown in eqs 4 and 5.6,7
Thioacetals, on treatment with mercury(II) fluoride in acetonitrile, give rise to a-fluoro sulfides, as shown in eq 6.8 Treatment of sulfoxides with N,N-Diethylaminosulfur Trifluoride also results in the formation of a-fluoro sulfides.9
Triphenylacetic acid, triphenylethylene, and triethyl phosphite have been selectively fluorinated in DMSO/HgF2 solutions under UV-visible illumination (eqs 7-9).10
Fluorodecarboxylations have also been accomplished with Xenon(II) Fluoride.11 Phosphites can also be oxidatively fluorinated with carbonyl fluoride12 or 2H-Hexafluoropropyl Azide.13
Suzanne T. Purrington
North Carolina State University, Raleigh, NC, USA