What is the Difference Between Alkoxymercuration and Oxymercuration?

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The key difference between alkoxymercuration and oxymercuration lies in the products they form and the nucleophiles involved in the reactions. Both reactions involve the addition of mercury (II) salts to alkenes, but they proceed differently:

  • Alkoxymercuration: In this reaction, an alkene reacts with an alcohol (in the presence of mercuric acetate). This initially gives an alkoxymercury intermediate, which then produces an ether followed by the reduction with sodium borohydride. This reaction is similar to oxymercuration, but the nucleophile is an alcohol instead of water.
  • Oxymercuration: In this reaction, an electrophilic addition mechanism takes place, transforming an alkene into a neutral alcohol. When an alkene is treated with a mercury (II) salt such as mercuric acetate, addition occurs across the C-C pi bond, resulting in a new C-OH bond and a C-Hg bond. This reaction is also called "solvomercuration" since addition will generally incorporate any solvent, whether it be H2O, alcohols, carboxylic acids, or others.

In summary, alkoxymercuration forms ethers from alkenes and alcohols, while oxymercuration forms neutral alcohols from alkenes. The choice of nucleophile (alcohol or water) and the product formed (ether or neutral alcohol) are the main differences between these two reactions.

Comparative Table: Alkoxymercuration vs Oxymercuration

The main differences between alkoxymercuration and oxymercuration are the reactants and the products formed in each reaction. Here is a comparison table highlighting the key differences:

Feature Alkoxymercuration Oxymercuration
Reactants Alkene, Alcohol, Mercury Salt Alkene, Water, Mercury Salt
Products Ether Neutral Alcohol
Mechanism Electrophilic Addition, Stabilized Carbocation Electrophilic Addition, Stabilized Carbocation

Both reactions involve the addition of a mercury salt, such as mercuric acetate, to an alkene. However, in alkoxymercuration, an alcohol is used instead of water, resulting in the formation of an ether. In contrast, oxymercuration uses water and produces a neutral alcohol as the final product. The mechanisms of both reactions are similar, involving electrophilic addition and stabilization of the carbocation intermediate by a mercury ion bridge.