Mercuric acetate Hg(OAc)2 is used for the oxymercuration of alkenes and alkynes. In the presence of alkenes and alkynes it will form a 3-membered ring bearing a positive charge on Hg, which can then undergo attack at the more substituted carbon (Markovnikov addition) to give alcohols or ethers. The C-Hg bond is then removed with sodium borohydride NaBH4.