Methane cannot be prepared by

Options

A. Corey-house synthesis
B. Wurtz reaction
C. Fittig reaction
D. All of these

Answer

To determine which method cannot be used to prepare methane (CH₄), let's analyze each option provided in the question:

### Step 1: Analyze Corey-House Synthesis
- **Corey-House Synthesis** involves the reaction of dialkylcuprate reagents with alkyl halides.
- The general reaction can be represented as:
\[ R_2CuLi + R'X \rightarrow R-R' + CuX + Li \]
- In this reaction, at least two carbon atoms are required to form an alkane. Therefore, it cannot produce methane, which has only one carbon atom.

### Step 2: Analyze Wurtz Reaction
- **Wurtz Reaction** involves the coupling of two alkyl halides in the presence of sodium metal, typically in dry ether:
\[ 2R-X + 2Na \rightarrow R-R + 2NaX \]
- Similar to Corey-House Synthesis, this reaction requires at least two carbon atoms from the alkyl halides to form an alkane. Thus, it cannot produce methane either.

### Step 3: Analyze Fittig Reaction
- **Fittig Reaction** involves the reaction of aryl halides with sodium in dry ether:
\[ 2Ar-X + 2Na \rightarrow Ar-Ar + 2NaX \]
- This reaction also results in the formation of biphenyl compounds, which contain more than one carbon atom. Therefore, it cannot be used to prepare methane.

### Conclusion
Since all three methods (Corey-House synthesis, Wurtz reaction, and Fittig reaction) require at least two carbon atoms to form an alkane, none of them can be used to prepare methane. Therefore, the correct answer is:
**D) All of these**

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