Mercuric Ion

Definition

The mercuric ion, denoted as Hg2+, is a positively charged ion of the element mercury. It is a key component in the chemical process known as oxymercuration, which is a method for the hydration of alkenes, adding water across the carbon-carbon double bond.

5 Must Know Facts For Your Next Test

1. The mercuric ion, Hg2+, acts as an electrophile in the oxymercuration reaction, facilitating the addition of water to the alkene.
2. Oxymercuration is a two-step process, where the mercuric ion first adds to the alkene, followed by the addition of water and the subsequent removal of the mercury.
3. The mercuric ion is a soft Lewis acid, meaning it preferentially binds to soft Lewis bases, such as the π-electrons of the alkene.
4. The presence of the mercuric ion lowers the activation energy of the hydration reaction, making it a more favorable and faster process.
5. The mercuric ion is typically introduced in the form of a mercury(II) salt, such as mercury(II) acetate or mercury(II) sulfate, which provides the necessary Hg2+ species.

Review Questions

• Explain the role of the mercuric ion in the oxymercuration reaction for the hydration of alkenes.
  • The mercuric ion, Hg2+, plays a crucial role in the oxymercuration reaction for the hydration of alkenes. As an electrophile, the mercuric ion first adds to the carbon-carbon double bond of the alkene, forming a cyclic mercury-containing intermediate. This intermediate then undergoes addition of water, followed by the removal of the mercury species, resulting in the formation of an alcohol product. The mercuric ion facilitates the hydration reaction by lowering the activation energy and making the process more favorable.
• Describe the two-step mechanism of the oxymercuration reaction and explain the function of the mercuric ion in each step.
  • The oxymercuration reaction for the hydration of alkenes occurs in two steps. In the first step, the mercuric ion, Hg2+, acts as an electrophile and adds to the carbon-carbon double bond of the alkene, forming a cyclic mercury-containing intermediate. In the second step, water is added to this intermediate, and the mercury species is subsequently removed, resulting in the formation of an alcohol product. The mercuric ion plays a crucial role in both steps by facilitating the electrophilic addition to the alkene and stabilizing the intermediate, ultimately making the hydration reaction more favorable and efficient.
• Analyze the factors that contribute to the effectiveness of the mercuric ion in the oxymercuration reaction and discuss how these factors influence the overall reaction outcome.
  • The effectiveness of the mercuric ion, Hg2+, in the oxymercuration reaction for the hydration of alkenes can be attributed to several factors. Firstly, the mercuric ion is a soft Lewis acid, meaning it preferentially binds to the soft π-electrons of the alkene, forming a stable intermediate. This selective binding lowers the activation energy of the reaction, making the hydration process more favorable. Additionally, the presence of the mercuric ion helps to stabilize the intermediate formed during the reaction, further facilitating the addition of water and the subsequent removal of the mercury species. Finally, the mercuric ion is typically introduced in the form of a mercury(II) salt, which provides the necessary Hg2+ species required for the reaction to proceed. These factors collectively contribute to the effectiveness of the mercuric ion in the oxymercuration reaction, leading to efficient hydration of alkenes and the formation of the desired alcohol products.

Related terms

Oxymercuration: A reaction in organic chemistry where an alkene is converted to an alcohol by the addition of water, facilitated by the presence of a mercury(II) salt and a proton source.

Hydration of Alkenes: The process of adding water across the carbon-carbon double bond of an alkene, resulting in the formation of an alcohol.

Electrophilic Addition: A type of reaction where an electrophile, such as the mercuric ion, adds to the carbon-carbon double bond of an alkene.