Mechanism of Mercury(ID)-Catalyzed Hydration of Alkynes The alkyne uses a pair of electrons to R一C attack the electrophilic mercury(I) Hg2+802 ion,yielding a mercury-containing ■ Electrophilic vinylie carbocation intermediate. addition of Hg(Il)to Nucleophilic attack of water on Hg'SO alkyne gives a the earbocation forms a C-O bond and yields a protonated mercury- vinylic cation containing enol. ■Vater adds and Hg+802 loses a proton ■Acidic reaction +HO condition is e olacement of Hg'by H'occurs sufficient to replace to give a neutral enol mercury by H +HO The enol under to give e the final ketone product Mechanism of Mercury(II)-Catalyzed Hydration of Alkynes „ Electrophilic addition of Hg(II) to alkyne gives a vinylic cation „ Water adds and loses a proton „ Acidic reaction condition is sufficient to replace mercury by H