The positive charge is shared within the three-membered mercury-containing bridge rather than being localized on one carbon. This electronic arrangement forms when the alkene attacks Hg(OAc)⁺ and mercury bonds to both alkene carbons. The shared charge helps describe why the reaction proceeds through a bridged intermediate instead of a freely formed carbocation.
Because mercury remains bonded to both carbons of the former double bond, the reaction does not produce a free carbocation that could reorganize its carbon skeleton. This distinguishes oxymercuration from pathways that involve discrete carbocation intermediates. Consequently, the carbon framework is retained while nucleophilic water proceeds to the next step.
Within the bridged intermediate, nucleophilic water attacks the more substituted carbon, giving the usual Markovnikov placement of the future hydroxyl group. The attack typically occurs from the face opposite the mercury bridge. This combination of regioselectivity and opposite-face attack explains how the intermediate controls both where water adds and how the substituents are oriented.
After water adds, deprotonation converts the initially attached water-derived group into the alcohol functionality. Reductive demercuration then removes the mercury component from the organomercury intermediate, completing conversion of the alkene-derived structure into an alcohol. These steps are sequential rather than alternative pathways, and together they finish the oxymercuration–demercuration transformation.
The sequence begins with alkene attack on Hg(OAc)⁺ to form the bridged intermediate. Water then attacks the more substituted carbon, typically from the opposite face, followed by deprotonation. A final reductive demercuration removes mercury and yields the alcohol. This workflow connects electrophilic addition, nucleophilic capture, proton transfer, and mercury removal.
This method is useful when an alcohol is needed from an alkene with typical Markovnikov regioselectivity and without carbocation rearrangement. Its synthetic value also comes from operating under mild conditions, as indicated by the transformation described in the source. The bridged mercury intermediate therefore links a predictable alkene addition pattern with practical alcohol preparation.