The key difference between oxymercuration and demercuration is that oxymercuration involves an electrophilic addition where an alkene transforms into a neutral alcohol, whereas demercuration involves the conversion of an alkene into Hg2+ salt and an organomercury intermediate.
Oxymercuration is a chemical reaction in which an electrophilic addition mechanism takes place, transforming an alkene into a neutral alcohol. Demercuration or oxymercuration-demercuration is a reaction in which an alkene converts into a Hg2+ salt and an oxygen nucleophile, forming an organomercury intermediate.
CONTENTS
1. Overview and Key Difference
2. What is Oxymercuration
3. What is Demercuration
4. Oxymercuration vs Demercuration in Tabular Form
5. Summary – Oxymercuration vs Demercuration
What is Oxymercuration?
Oxymercuration is a chemical reaction in which an electrophilic addition mechanism takes place, transforming an alkene into a neutral alcohol. In this process, we can observe the reaction between an alkene and mercuric acetate in an aqueous solution. This yields the addition of an acetoxymercury group and an OH group across the double bond.
Figure 01: An Oxymercuration Reaction Mechanism in Sequential Order
During the oxymercuration process, carbocations do not form. Therefore, there are rearrangement steps as well. This reaction takes place according to Markonikov’s rule, which describes that when the addition of protic acid with the formula of HX (where X= halogen) or H2O (considered as H-OH) to an alkene, hydrogen attaches to the double-bonded carbon with the greater number of hydrogen atoms, while the halogen (X) attaches to the other carbon.
Moreover, oxymercuration is an anti-addition reaction. This means the OH group will always get added to the more substituted carbon atom and the two groups tend to be trans to each other, respectively.
Figure 02: An Application of Oxymercuration
Usually, an oxymercuration reaction is followed by a reductive demercuration reaction; hence we call it an oxymercuration-reduction reaction. Practically, this reduction reaction is more common than the oxymercuration reaction.
What is Demercuration?
Demercuration or oxymercuration-demercuration is the reaction in which an alkene converts into a Hg2+ salt and an oxygen nucleophile, forming an organomercury intermediate. The oxygen nucleophile we use here can be water or an alcohol. In other words, in demercuration, a hydrogen atom at the CH2 site and a hydroxyl group on the ring carbon atom react with each other. It gives the predicted Markovnikov product through indirect hydration of an alkene.
What is the Difference Between Oxymercuration and Demercuration?
Oxymercuration is a chemical reaction in which an electrophilic addition mechanism takes place, transforming an alkene into a neutral alcohol. Demercuration, on the other hand, is the reaction in which an alkene converts into a Hg2+ salt and an oxygen nucleophile, forming an organomercury intermediate. Therefore, the key difference between oxymercuration and demercuration is that oxymercuration involves an electrophilic addition where an alkene transforms into a neutral alcohol, whereas demercuration involves the conversion of an alkene into Hg2+ salt and an organomercury intermediate.
Below is a summary of the difference between oxymercuration and demercuration in tabular form for side by side comparison.
Summary – Oxymercuration vs Demercuration
Oxymercuration is a chemical reaction in which an electrophilic addition mechanism takes place, transforming an alkene into a neutral alcohol. Demercuration or oxymercuration-demercuration is the reaction in which an alkene converts into a Hg2+ salt and an oxygen nucleophile, forming an organomercury intermediate. Therefore, the key difference between oxymercuration and demercuration is that oxymercuration involves an electrophilic addition where an alkene transforms into neutral alcohol, whereas demercuration involves the conversion of an alkene into Hg2+ salt and an organomercury intermediate.
Reference:
1. “Oxymercuration Demercuration.” An Overview | ScienceDirect Topics.
2. “Hydration: Oxymercuration-Demercuration.” Chemistry – Libre Text
Image Courtesy:
1. “Oxymercuration Stepwise” By The Jackal at English Wikipedia – Transferred from en.wikipedia to Commons by Ronhjones using Commons Helper. (Public Domain) via Commons Wikimedia
2. “Oxymerc other” By Vkk0000 – Own work (CC BY-SA 3.0) via Commons Wikimedia
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