Cleavage of Grignard reagent results in the formation of

Options

A. carbonium ion
B. carbanion
C. free radical
D. carbene

Answer

To solve the question regarding the cleavage of Grignard reagent and what it results in, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Grignard Reagents**:
- Grignard reagents have the general formula \( R-Mg-X \), where \( R \) is an organic group, \( Mg \) is magnesium, and \( X \) is a halogen (like bromine or chlorine).

2. **Polarity of the Carbon-Magnesium Bond**:
- The bond between carbon and magnesium is polar because carbon is more electronegative than magnesium. This means that the electrons in the bond are pulled closer to the carbon atom, giving it a partial negative charge (\( \delta^- \)) and leaving magnesium with a partial positive charge (\( \delta^+ \)).

3. **Cleavage of the Grignard Reagent**:
- When the Grignard reagent cleaves, the bond between carbon and magnesium breaks. The bonding pair of electrons is taken by the carbon atom.

4. **Formation of Products**:
- After cleavage, the carbon atom retains both of the bonding electrons, resulting in a carbon ion (\( R^- \)), which has three bonds and a lone pair of electrons, giving it a complete negative charge.
- The magnesium atom, having lost its bonding electrons, becomes positively charged (\( Mg^{2+} \)) and is typically associated with the halogen \( X \) (e.g., bromide \( Br^- \)).

5. **Conclusion**:
- Therefore, the cleavage of the Grignard reagent results in the formation of a carbon ion and a magnesium halide. The correct answer to the question is that it forms a carbon ion.

### Final Answer:
The cleavage of Grignard reagent results in the formation of a carbon ion.

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