Which among the following reagents convert alkyl halide into alkane?

Options

A. `LiAlH_(4)`
B. NA/dry ether
C. `R_(2) "Cul"_(4)`
D. All of these

Answer

To determine which reagents can convert alkyl halides into alkanes, we need to analyze each reagent's mechanism and reaction type. Here’s a step-by-step breakdown:

### Step 1: Understanding Alkyl Halides
Alkyl halides have the general formula R-X, where R represents an alkyl group and X is a halogen (Cl, Br, or I). The goal is to convert R-X into R-H (an alkane).

**Hint:** Remember that alkyl halides are reactive due to the presence of the halogen, which can be replaced or removed to form alkanes.

### Step 2: Analyzing the First Reagent - Lithium Aluminum Hydride (LiAlH4)
LiAlH4 is a strong reducing agent that can donate hydride ions (H-) to alkyl halides. When it reacts with an alkyl halide like CH3Cl (methyl chloride), the halogen (Cl) is replaced by a hydrogen atom, forming methane (CH4).

**Reaction:**
\[ \text{R-X} + \text{LiAlH}_4 \rightarrow \text{R-H} + \text{LiX} + \text{AlH}_3 \]

**Hint:** Reducing agents like LiAlH4 provide H- ions that can replace halogens in alkyl halides.

### Step 3: Analyzing the Second Reagent - Sodium in Dry Ether
In the presence of sodium and dry ether, two moles of alkyl halide can undergo a Wurtz reaction. This reaction leads to the coupling of two alkyl halide molecules, forming a higher alkane.

**Reaction:**
\[ 2 \text{R-X} + 2 \text{Na} \rightarrow \text{R-R} + 2 \text{NaX} \]

**Hint:** The Wurtz reaction is a coupling reaction that forms alkanes by removing halides and combining alkyl groups.

### Step 4: Analyzing the Third Reagent - Gilman Reagent (R2CuLi)
Gilman reagents (R2CuLi) can also react with alkyl halides. The reaction involves the coupling of the alkyl group from the Gilman reagent with the alkyl halide, resulting in the formation of a new alkane and lithium halide.

**Reaction:**
\[ \text{R-X} + \text{R}_2\text{CuLi} \rightarrow \text{R-R} + \text{R-Cu} + \text{LiX} \]

**Hint:** Gilman reagents facilitate coupling reactions, which can also lead to the formation of alkanes.

### Conclusion
All three reagents (LiAlH4, sodium in dry ether, and Gilman reagent) can convert alkyl halides into alkanes through different mechanisms. Therefore, the answer is that all of the mentioned reagents can achieve this conversion.

**Final Answer:** All of the above reagents convert alkyl halides into alkanes.