Which of the following reactions can be used to prepare alkanes?

Options

A. Corey-House synthesis
B. Williamson synthesis
C. Friedel-Crafts reactions
D. Grignard reagent

Answer

To determine which of the given reactions can be used to prepare alkanes, we will analyze each option step by step.

### Step-by-Step Solution:

1. **Option A: Corrie-Haus Synthesis**
- In the Corrie-Haus synthesis, an alkyl halide reacts with lithium to form an organolithium compound (RLi) and lithium halide (LiX).
- Two moles of RLi then react with copper iodide (CuI) to form a compound R2CuLi and lithium iodide (LiI).
- This R2CuLi can react with another alkyl halide (R'X) to produce an alkane (RR') along with RCu and LiX.
- **Conclusion:** This reaction can produce alkanes.

2. **Option B: Williamson Synthesis**
- In Williamson synthesis, an alcohol (R1OH) reacts with sodium to form an alkoxide (R1O^-Na^+).
- This alkoxide then reacts with an alkyl halide (R2X) to form an ether (R1OR2) and sodium halide (NaX).
- **Conclusion:** This reaction produces ethers, not alkanes.

3. **Option C: Friedel-Craft Reaction**
- The Friedel-Craft reaction involves the alkylation of an aromatic ring using an alkyl halide (RCl) in the presence of a Lewis acid (like AlCl3).
- This results in the formation of alkyl-substituted benzene (alkylbenzene).
- **Conclusion:** This reaction does not produce alkanes, but rather alkylated aromatic compounds.

4. **Option D: Grignard Reagent**
- Grignard reagents (R-MgX) can react with water or dilute acid to produce alkanes (RH) from the alkyl group (R) and hydrogen (H).
- However, Grignard reagents can also react with carbonyl compounds to form alcohols or other products.
- **Conclusion:** While Grignard reagents can produce alkanes, they are not exclusively used for that purpose.

### Final Answer:
The reaction that can be used to prepare alkanes is **Option A: Corrie-Haus Synthesis**.

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