Is this grignard preparation mechanism correct?

In summary: So in summary, the conversation discusses the mechanism of a reaction in which magnesium transfers an electron to a C-X bond, resulting in a Mg radical. The halogen atom leaves with 2 electrons, creating a carbon radical. A negatively charged bromide ion then forms an ionic bond with the positively charged Mg radical. Finally, the carbon and Mg radicals use their single electrons to form a new covalent bond. It is noted that the mechanism drawing may not accurately represent the formal charges involved in the reaction.
  • #1
Horseb0x
25
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[PLAIN]http://img443.imageshack.us/img443/6488/mechanisma1.png [Broken]
The magnesium transfers an electron to the C-X bond, yielding a Mg radical. The halogen atom leaves with 2 electrons from the bond and the carbon is converted into a radical. The negatively charged bromide ion forms an ionic bond with the positively charged Mg radical. The single electrons of the carbon radical and Mg radical are used to form a new covalent bond.

Is this correct? Also is my wording and mechanism drawing adequate?
 
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  • #3
Horseb0x said:
[PLAIN]http://img443.imageshack.us/img443/6488/mechanisma1.png [Broken]
The magnesium transfers an electron to the C-X bond, yielding a Mg radical. The halogen atom leaves with 2 electrons from the bond and the carbon is converted into a radical. The negatively charged bromide ion forms an ionic bond with the positively charged Mg radical. The single electrons of the carbon radical and Mg radical are used to form a new covalent bond.
Is this correct? Also is my wording and mechanism drawing adequate?

I don't agree with the formal negative charge you have shown. Remember that it gained 1 electron from Mg and lost one to Br.
 
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1. What is a Grignard reagent?

A Grignard reagent is an organometallic compound that is commonly used in organic chemistry reactions. It is typically formed by reacting an alkyl or aryl halide with magnesium metal in the presence of an ether solvent.

2. How does the Grignard reagent function in chemical reactions?

The Grignard reagent acts as a strong nucleophile, attacking electrophilic sites on other molecules. It can also function as a base, deprotonating acidic hydrogens. This allows for a wide variety of reactions to take place, making the Grignard reagent a versatile tool in organic synthesis.

3. What is the mechanism for preparing a Grignard reagent?

The preparation of a Grignard reagent involves the reaction of an alkyl or aryl halide with magnesium metal in the presence of an ether solvent. The magnesium metal acts as a reducing agent, converting the halide into an alkyl or aryl magnesium halide compound. This is followed by the addition of the desired substrate, forming the Grignard reagent.

4. How do you ensure a correct Grignard preparation mechanism?

To ensure a correct Grignard preparation mechanism, it is important to use dry and pure reagents, as any moisture or impurities can hinder the reaction. The reaction should also be carried out under an inert atmosphere, such as nitrogen, to prevent oxidation. Additionally, the reaction should be monitored by TLC or NMR to confirm the formation of the desired Grignard reagent.

5. What are some common mistakes when preparing a Grignard reagent?

Some common mistakes when preparing a Grignard reagent include using impure or moist reagents, not removing all air from the reaction vessel, and not using an appropriate solvent. It is also important to avoid excess magnesium, as it can lead to the formation of side products. Additionally, care must be taken when handling the highly reactive Grignard reagent, as it can react violently with water or other protic solvents.

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