By which of the following reagent butanoic acid can be converted into butane :

Options

A. `HI//P//Delta`
B. `NaOH//CaO`
C. `CH_(3)MhBr`
D. All of these

Explanation

To convert butanoic acid into butane, we can use the following step-by-step approach:

### Step-by-Step Solution:

1. **Identify the Structure of Butanoic Acid**:
- Butanoic acid has the molecular formula \( C_4H_8O_2 \) and its structure can be represented as:
\[ CH_3-CH_2-CH_2-COOH \]

2. **Select the Appropriate Reagent**:
- The question asks for a reagent that can convert butanoic acid into butane. The options provided include various reagents, but we need to identify one that effectively removes the carboxylic acid group and replaces it with hydrogen.

3. **Consider the Reagent HI with Red Phosphorus**:
- One of the reagents mentioned is Hydroiodic acid (HI) in the presence of red phosphorus. This combination can reduce the carboxylic acid group to an alkane.
- The reaction can be summarized as:
\[ CH_3-CH_2-CH_2-COOH + HI \xrightarrow{Red \, P, \, heat} CH_3-CH_2-CH_2-CH_3 + H_2O \]
- This results in the formation of butane (\( C_4H_{10} \)).

4. **Evaluate Other Reagents**:
- **Soda Lime (NaOH + CaO)**: This reagent is used for decarboxylation, which would remove the carboxylic group but would yield propane instead of butane.
- **Grignard Reagent**: The reaction with a Grignard reagent would lead to the formation of methane and not butane, as it would react with the acidic hydrogen of the carboxylic acid.

5. **Conclusion**:
- Therefore, the correct reagent that converts butanoic acid into butane is **HI in the presence of red phosphorus**, which is option A.

### Final Answer:
The reagent that can convert butanoic acid into butane is **HI with red phosphorus**.

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