Alkanes can be obtained from carboxylic acids by

Options

A. `LiAIH_(4)`
B. Decarboxylation
C. Kolbe's electrolysis
D. Clemmensen's reduction

Answer

To obtain alkanes from carboxylic acids, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Carboxylic Acid**:
Let's consider a generic carboxylic acid represented as RCH2COOH. Here, R represents any alkyl group.

2. **Decarboxylation Process**:
The primary method to convert carboxylic acids to alkanes is through a process called decarboxylation. This involves the removal of a carboxyl group (-COOH) from the carboxylic acid.

3. **Use of Soda Lime**:
To perform decarboxylation, we can treat the carboxylic acid with soda lime (a mixture of sodium hydroxide and calcium oxide) and apply heat. The reaction can be represented as:
\[ RCH2COOH + \text{NaOH (soda lime)} \xrightarrow{\text{heat}} RCH3 + \text{Na2CO3} + \text{H2O} \]
In this reaction, the carboxyl group is removed as carbon dioxide (CO2), resulting in the formation of an alkane (RCH3).

4. **Alternative Method - Kolbe Electrolysis**:
Another method to obtain alkanes from carboxylic acids is through Kolbe electrolysis. In this process:
- The carboxylic acid is subjected to electrolysis, leading to the formation of radicals.
- For example, if we take acetic acid (CH3COOH), during electrolysis, it can produce ethane (C2H6) as follows:
\[ 2 \text{CH3COOH} \xrightarrow{\text{electrolysis}} \text{C2H6} + 2 \text{CO2} + \text{H2} \]
Here, the radicals combine to form the alkane.

5. **Conclusion**:
Therefore, the two primary methods to obtain alkanes from carboxylic acids are through decarboxylation using soda lime and through Kolbe electrolysis.

### Final Answer:
Alkanes can be obtained from carboxylic acids by **decarboxylation using soda lime** and **Kolbe electrolysis**.

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